Gymnastik- och idrottshögskolan, GIH

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  • 1.
    Andersson, Eva A
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology. Karolinska institutet.
    Frank, Per
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology. Karolinska institutet.
    Pontén, Marjan
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's research group.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology. Karolinska institutet.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Sahlin, Kent
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Improving Strength, Power, Muscle Aerobic Capacity, and Glucose Tolerance through Short-term Progressive Strength Training Among Elderly People.2017In: Journal of Visualized Experiments, E-ISSN 1940-087X, no 125Article in journal (Refereed)
    Abstract [en]

    This protocol describes the simultaneous use of a broad span of methods to examine muscle aerobic capacity, glucose tolerance, strength, and power in elderly people performing short-term resistance training (RET). Supervised progressive resistance training for 1 h three times a week over 8 weeks was performed by RET participants (71±1 years, range 65-80). Compared to a control group without training, the RET showed improvements on the measures used to indicate strength, power, glucose tolerance, and several parameters of muscle aerobic capacity. Strength training was performed in a gym with only robust fitness equipment. An isokinetic dynamometer for knee extensor strength permitted the measurement of concentric, eccentric, and static strength, which increased for the RET group (8-12% post- versus pre-test). The power (rate of force development, RFD) at the initial 0-30 ms also showed an increase for the RET group (52%). A glucose tolerance test with frequent blood glucose measurements showed improvements only for the RET group in terms of blood glucose values after 2 h (14%) and the area under the curve (21%). The blood lipid profile also improved (8%). From muscle biopsy samples prepared using histochemistry, the amount of fiber type IIa increased, and a trend towards a decrease in IIx in the RET group reflected a change to a more oxidative profile in terms of fiber composition. Western blot (to determine the protein content related to the signaling for muscle protein synthesis) showed a rise of 69% in both Akt and mTOR in the RET group; this also showed an increase in mitochondrial proteins for OXPHOS complex II and citrate synthase (both ~30%) and for complex IV (90%), in only the RET group. We demonstrate that this type of progressive resistance training offers various improvements (e.g., strength, power, aerobic capacity, glucose tolerance, and plasma lipid profile).

  • 2.
    Bjerkefors, Anna
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Nordlund Ekblom, Maria M
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Josefsson, Karin
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Thorstensson, Alf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Deep and superficial abdominal muscle activation during trunk stabilization exercises with and without instruction to hollow.2010In: Manual Therapy, ISSN 1356-689X, E-ISSN 1532-2769, Vol. 15, no 5, p. 502-7Article in journal (Refereed)
    Abstract [en]

    The deepest muscle of the human ventro-lateral abdominal wall, the Transversus Abdominis (TrA), has been ascribed a specific role in spine stabilization, which has motivated special core stability exercises and hollowing instruction to specifically involve this muscle. The purpose here was to evaluate the levels of activation of the TrA and the superficial Rectus Abdominis (RA) muscles during five common stabilization exercises performed in supine, bridging and four-point kneeling positions, with and without instruction to hollow, i.e. to continuously pull the lower part of the abdomen towards the spine. Nine habitually active women participated and muscle activity was recorded bilaterally from TrA and RA with intramuscular fine-wire electrodes introduced under the guidance of ultrasound. Results showed that subjects were able to selectively increase the activation of the TrA, isolated from the RA, with the specific instruction to hollow and that side differences in the amplitude of TrA activity, related to the asymmetry of the exercises, remained even after the instruction to hollow. The exercises investigated caused levels of TrA activation from 4 to 43% of that during maximal effort and can thus be used clinically to grade the load on the TrA when designing programs aiming at training that muscle.

  • 3.
    Blackwood, Sarah J
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Horwath, Oscar
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics. Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
    Pontén, Marjan
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Apro, William
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics. Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden..
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health. Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden..
    Larsen, Filip J
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Katz, Abram
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Extreme Variations in Muscle Fiber Composition Enable Detection of Insulin Resistance and Excessive Insulin Secretion.2022In: Journal of Clinical Endocrinology and Metabolism, ISSN 0021-972X, E-ISSN 1945-7197, Vol. 107, no 7, p. e2729-e2737, article id dgac221Article in journal (Refereed)
    Abstract [en]

    CONTEXT: Muscle fiber composition is associated with peripheral insulin action.

    OBJECTIVE: We investigated whether extreme differences in muscle fiber composition are associated with alterations in peripheral insulin action and secretion in young, healthy subjects who exhibit normal fasting glycemia and insulinemia.

    METHODS: Relaxation time following a tetanic contraction was used to identify subjects with a high or low expression of type I muscle fibers: group I (n=11), area occupied by type I muscle fibers = 61.0 ± 11.8%; group II (n=8), type I area = 36.0 ± 4.9% (P<0.001). Biopsies were obtained from the vastus lateralis muscle and analyzed for mitochondrial respiration on permeabilized fibers, muscle fiber composition and capillary density. An intravenous glucose tolerance test was performed and indices of glucose tolerance, insulin sensitivity and secretion were determined.

    RESULTS: Glucose tolerance was similar between groups, whereas whole-body insulin sensitivity was decreased by ~50% in group II vs group I (P=0.019). First phase insulin release (area under the insulin curve during 10 min after glucose infusion) was increased by almost 4-fold in group II vs I (P=0.01). Whole-body insulin sensitivity was correlated with % area occupied by type I fibers (r=0.54; P=0.018) and capillary density in muscle (r=0.61; P=0.005), but not with mitochondrial respiration. Insulin release was strongly related to % area occupied by type II fibers (r=0.93; P<0.001).

    CONCLUSIONS: Assessment of muscle contractile function in young healthy subjects may prove useful in identifying individuals with insulin resistance and enhanced glucose stimulated insulin secretion prior to onset of clinical manifestations.

  • 4.
    Blackwood, Sarah J
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Horwath, Oscar
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics. Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden..
    Pontén, Marjan
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Apro, William
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics. Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health. Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden..
    Larsen, Filip J
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Katz, Abram
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Insulin resistance after a 3-day fast is associated with an increased capacity of skeletal muscle to oxidize lipids.2023In: American Journal of Physiology. Endocrinology and Metabolism, ISSN 0193-1849, E-ISSN 1522-1555, Vol. 324, no 5, p. E390-E401Article in journal (Refereed)
    Abstract [en]

    There is a debate on whether lipid-mediated insulin resistance derives from an increased or decreased capacity of muscle to oxidize fats. Here we examine the involvement of muscle fiber composition in the metabolic responses to a 3-day fast (starvation, which results in increases in plasma lipids and insulin resistance) in two groups of healthy young subjects: 1, area occupied by type I fibers = 61.0 ± 11.8%; 2, type I area = 36.0 ± 4.9% (P<0.001). Muscle biopsies and intravenous glucose tolerance tests were performed after an overnight fast and after starvation. Biopsies were analyzed for muscle fiber composition and mitochondrial respiration. Indices of glucose tolerance and insulin sensitivity were determined. Glucose tolerance was similar in both groups after an overnight fast and deteriorated to a similar degree in both groups after starvation. In contrast, whole-body insulin sensitivity decreased markedly after starvation in group 1 (P<0.01), whereas the decrease in group 2 was substantially smaller (P=0.06). Non-esterified fatty acids and β-hydroxybutyrate levels in plasma after an overnight fast were similar between groups and increased markedly and comparably in both groups after starvation, demonstrating similar degrees of lipid load. The capacity of permeabilized muscle fibers to oxidize lipids was significantly higher in group 1 vs. 2, whereas there was no significant difference in pyruvate oxidation between groups. The data demonstrate that loss of whole-body insulin sensitivity after short-term starvation is a function of muscle fiber composition and is associated with an elevated rather than a diminished capacity of muscle to oxidize lipids.

  • 5.
    Blom, Victoria
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health. Karolinska institutet, Stockholm, Sweden ; Stockholm University, Sweden.
    Drake, Emma
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Kallings, Lena
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Nooijen, Carla F J
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    The effects on self-efficacy, motivation and perceived barriers of an intervention targeting physical activity and sedentary behaviours in office workers: a cluster randomized control trial.2021In: BMC Public Health, E-ISSN 1471-2458, Vol. 21, no 1, article id 1048Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: The importance of physical activity on health is clear, but changing behaviour is difficult. Successful interventions aiming to improve physical activity and reduce sedentary behaviour is therefore of importance. The aim of this study was to evaluate effects on motivation, self-efficacy and barriers to change behaviour from two different behavioural intervention focusing either on reducing sedentary behaviour or on increasing physical activity as compared to a waiting list control group.

    METHODS: The study was designed as a cluster randomized control trial (RCT) within two private companies. Self-efficacy, motivation and perceived barriers were together with demographic variables assessed before and after a 6-month intervention. Participant cluster teams were randomly allocated to either the physical activity intervention (iPA), the sedentary behaviour intervention (iSED), or control group. The intervention was multi componential and included motivational counselling based on Cognitive behaviour therapy and Motivational interviewing, group activities and management involvement. Group differences were determined using Bayesian multilevel modelling (parameter estimate; credible interval (CI)), analysing complete cases and those who adhered to the protocol by adhering to at least 3 out of 5 intervention sessions.

    RESULTS: After the intervention, the complete cases analysis showed that the iPA group had significantly higher autonomous motivation (0.33, CI: 0.05-0.61) and controlled motivation (0.27, CI: 0.04-0.51) for physical activity compared with the control group. The iSED group scored less autonomous and controlled motivation compared to the iPA group (0.38, CI: - 0.69- -0.087 respectively - 0.32, CI: - 0.57-0.07) but no significant differences compared with the control group. Among individuals that adhered to the protocol, the results showed higher scores on Exercise (3.03, CI: 0.28-6.02) and Sedentary self-efficacy (3.59, CI: 0.35-7.15) for individuals in the iPA group and on Sedentary self-efficacy (4.77, CI: 0.59-9.44) for the iSED group compared to the control group.

    CONCLUSION: These findings indicate that the interventions were successful in increasing self-efficacy in each intervention group and autonomous motivation for exercise in the iPA group, in particular when actively participating in the motivational counselling sessions.

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  • 6.
    Bojsen-Møller, Emil
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Boraxbekk, Carl-Johan
    Copenhagen University Hospital, Hvidovre, Denmark.
    Ekblom, Örjan
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's research group.
    Blom, Victoria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Sport Psychology research group.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. Karolinska institutet.
    Relationships between Physical Activity, Sedentary Behaviour and Cognitive Functions in Office Workers.2019In: International Journal of Environmental Research and Public Health, ISSN 1661-7827, E-ISSN 1660-4601, Vol. 16, no 23, article id E4721Article in journal (Refereed)
    Abstract [en]

    Increasing evidence from animal experiments suggests that physical activity (PA) promotes neuroplasticity and learning. For humans, most research on the relationship between PA, sedentary behaviour (SB), and cognitive function has relied on self-reported measures of behaviour. Office work is characterised by high durations of SB combined with high work demands. While previous studies have shown that fitter office workers outperform their less fit colleagues in cognitive tests, the importance of PA and SB remains unknown. This study investigated associations between objectively measured PA and SB, using hip-worn accelerometers, and cognitive functions in 334 office workers. Time spent in moderate-to-vigorous PA (MVPA) was not associated with any cognitive outcome. However, time spent in SB tended to be positively associated with words recalled in free recall (β = 0.125). For the least fit participants, the average length of MVPA bouts was favourably related to Stroop performance (β = -0.211), while for the fitter individuals, a longer average length of MVPA bouts was related to worse recognition (β = -0.216). While our findings indicate that the length of MVPA bouts was associated with better Stroop performance in the least fit participants, our findings do not support the notion that more time spent in MVPA or less time in SB is associated with better cognitive function.

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  • 7.
    Bojsen-Møller, Emil
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Tarassova, Olga
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Dunstan, D W
    Baker Heart and Diabetes Institute, Melbourne, VIC, Australia.
    Ekblom, Örjan
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    The effect of breaking up prolonged sitting on paired associative stimulation-induced plasticity.2020In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 238, p. 2497-2506Article in journal (Refereed)
    Abstract [en]

    Paired associative stimulation (PAS) can induce plasticity in the motor cortex, as measured by changes in corticospinal excitability (CSE). This effect is attenuated in older and less active individuals. Although a single bout of exercise enhances PAS-induced plasticity in young, physically inactive adults, it is not yet known if physical activity interventions affect PAS-induced neuroplasticity in middle-aged inactive individuals. Sixteen inactive middle-aged office workers participated in a randomized cross-over design investigating how CSE and short-interval intracortical inhibition (SICI) were affected by PAS preceded by 3 h of sitting (SIT), 3 h of sitting interrupted every 30 min by 3 min of frequent short bouts of physical activity (FPA) and 2.5 h of sitting followed by 25 min of moderate-intensity exercise (EXE). Transcranial magnetic stimulation was applied over the primary motor cortex (M1) of the dominant abductor pollicis brevis to induce recruitment curves before and 5 min and 30 min post-PAS. Linear mixed models were used to compare changes in CSE using time and condition as fixed effects and subjects as random effects. There was a main effect of time on CSE and planned within-condition comparisons showed that CSE was significantly increased from baseline to 5 min and 30 min post-PAS, in the FPA condition, with no significant changes in the SIT or EXE conditions. SICI decreased from baseline to 5 min post-PAS, but this was not related to changes in CSE. Our findings suggest that in middle-aged inactive adults, FPAs may promote corticospinal neuroplasticity. Possible mechanisms are discussed.

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  • 8.
    Bojsen-Møller, Emil
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Tarassova, Olga
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Ekblom, Örjan
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Activity breaks during prolonged sitting enhance responses to paired associative stimulation2019In: Brain Stimulation: Basic, Translational, and Clinical Research in Neuromodulation, Volume 12, Issue 2, 466, Elsevier, 2019, Vol. 12, no 2Conference paper (Refereed)
  • 9.
    Bojsen-Møller, Emil
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Wang, Rui
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health. Division of Clinical Geriatrics, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden..
    Nilsson, Jonna
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Heiland, Emerald G
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health. Department of Surgical Sciences, Medical Epidemiology, University of Uppsala, Uppsala, Sweden..
    Boraxbekk, Carl-Johan
    Danish Research Centre for Magnetic Resonance (DRCMR), Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital - Amager and Hvidovre, Copenhagen, Denmark.; Department of Radiation Sciences, Diagnostic Radiology, Umeå University, Umeå, Sweden.; Institute of Sports Medicine Copenhagen (ISMC) and Department of Neurology, Copenhagen University Hospital Bispebjerg, Copenhagen, Denmark.; Institute for Clinical Medicine, Faculty of Medical and Health Sciences, University of Copenhagen, Copenhagen, Denmark..
    Kallings, Lena
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health. Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
    The effect of two multi-component behavior change interventions on cognitive functions.2022In: BMC Public Health, E-ISSN 1471-2458, Vol. 22, no 1, article id 1082Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: We previously reported the effects of two cluster-randomized 6-month multi-component workplace interventions, targeting reducing sedentary behavior or increasing physical activity among office workers, on movement behaviors and cardiorespiratory fitness. The primary aim of this study was to investigate the effects of these interventions on cognitive functions compared to a wait-list control group. The secondary aims were to examine if changes in cognition were related to change in cardiorespiratory fitness or movement behaviors and if age, sex, or cardiorespiratory fitness moderated these associations.

    METHODS: Both interventions encompassed multi-components acting on the individual, environmental, and organizational levels and aimed to change physical activity patterns to improve mental health and cognitive function. Out of 263 included participants, 139 (mean age 43 years, 76% females) completed a neuropsychological test battery and wore accelerometers at baseline and 6-month follow-up. The intervention effect (aim 1) on cognitive composite scores (i.e., Executive Functions, Episodic Memory, Processing Speed, and Global Cognition) was investigated. Additionally, associations between changes in movement behaviors and cardiorespiratory fitness, and changes in cognition were examined (aim 2). Moreover, age, sex, and cardiorespiratory fitness level were investigated as possible moderators of change associations (aim 3).

    RESULTS: Overall, cognitive performance improved from baseline to follow-up, but the change did not differ between the intervention groups and the control group. Changes in cardiorespiratory fitness or any movement behavior category did not predict changes in cognitive functions. The association between changes in time in bed and changes in both Executive Function and Global Cognition were moderated by age, such that a more positive relation was seen with increasing age. A less positive association was seen between changes in sedentary behavior and Processing Speed for men vs. women, whereas higher cardiorespiratory fitness was related to a more positive association between changes in moderate-intensity physical activity and Global Cognition.

    CONCLUSION: The lack of an intervention effect on cognitive functions was expected since the intervention did not change movement behavior or fitness. Age, sex, and cardiorespiratory fitness level might moderate the relationships between movement behaviors and cognitive functions changes.

    TRIAL REGISTRATION: ISRCTN92968402 . Registered 09/04/2018.

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  • 10.
    Brink-Elfegoun, Thibault
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences.
    Holmberg, Hans-Christer
    Nordlund Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    Neuromuscular and circulatory adaptation during combined arm and leg exercise with different maximal work loads.2007In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 101, no 5, p. 603-11Article in journal (Refereed)
    Abstract [en]

    Cardiopulmonary kinetics and electromyographic activity (EMG) during exhausting exercise were measured in 8 males performing three maximal combined arm+leg exercises (cA+L). These exercises were performed at different rates of work (mean+/-SD; 373+/-48, 429+/-55 and 521+/-102 W) leading to different average exercise work times in all tests and subjects. VO2 reached a plateau versus work rate in every maximal cA+L exercise (range 6 min 33 s to 3 min 13 s). The three different exercise protocols gave a maximal oxygen consumption (VO2MAX) of 4.67+/-0.57, 4.58+/-0.52 and 4.66+/-0.53 l min(-1) (P=0.081), and a maximal heart rate (HRmax) of 190+/-6, 189+/-4 and 189+/-6 beats min(-1) (P=0.673), respectively. Root mean square EMG (EMGRMS) of the vastus lateralis and the triceps brachii muscles increased with increasing rate of work and time in all three cA+L protocols. The study demonstrates that despite different maximal rates of work, leading to different times to exhaustion, the circulatory adaptation to maximal exercise was almost identical in all three protocols that led to a VO2 plateau. The EMG(RMS) data showed increased muscle recruitment with increasing work rate, even though the HRmax and VO2MAX was the same in all three cA+L protocols. In conclusion, these findings do not support the theory of the existence of a central governor (CG) that regulates circulation and neuronal output of skeletal muscles during maximal exercise.

  • 11. Broström, Eva
    et al.
    Nordlund Ekblom, Maria M
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Cresswell, Andrew G
    Plantar- and dorsiflexor strength in prepubertal girls with juvenile idiopathic arthritis.2004In: Archives of Physical Medicine and Rehabilitation, ISSN 0003-9993, E-ISSN 1532-821X, Vol. 85, no 8, p. 1224-30Article in journal (Refereed)
    Abstract [en]

    OBJECTIVE: To compare lower-leg strength of young girls with polyarticular juvenile idiopathic arthritis (JIA) with that of healthy, age-matched controls. DESIGN: Isometric and isokinetic strength tests of the plantar- and dorsiflexors. All strength measures were made at an ankle angle of 90 degrees. Isokinetic plantar- and dorsiflexor measures were made at 15 degrees/s during shortening (concentric) and lengthening (eccentric) actions. SETTING: Strength testing laboratory. PARTICIPANTS: Ten prepubertal girls diagnosed with JIA and 10 healthy girls. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Isometric and isokinetic plantar- and dorsiflexor strength. RESULTS: Isometric plantar- and dorsiflexion torques were significantly lower (48% and 38% respectively; P<.05) for the children with JIA than for the controls. The JIA group also produced lower shortening plantarflexion torques (52%, P<.05). Lengthening plantarflexor torques did not differ significantly between the 2 groups (P<.05). Controls were stronger than the JIA group for both shortening and lengthening maximal dorsiflexor actions (P<.05). All children were 4 to 5 times stronger in plantarflexion than in dorsiflexion. CONCLUSIONS: Girls with JIA had significantly less plantar- and dorsiflexor strength than age-matched, healthy peers. The reduced strength of children with JIA is likely to affect function in daily activities and probably contributes to reduced levels of physical activity.

  • 12.
    Crommert, M Eriksson
    et al.
    Örebro Universitet.
    Nordlund Ekblom, Maria M
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Thorstensson, Alf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Activation of transversus abdominis varies with postural demand in standing.2011In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 33, no 3, p. 473-7Article in journal (Refereed)
    Abstract [en]

    Transversus abdominis (TrA) is a multifunctional muscle, being involved in pressure regulation within the abdominal cavity and thereby in direction independent stabilization of the spine and resistance to imposed trunk flexion moments. Indirect evidence suggests a role of TrA also in postural control of the erect human trunk. The main purpose here was to investigate if the magnitude of TrA activation is related to postural demand. Eleven healthy males performed seven different symmetrical static bilateral arm positions holding 3 kg in each hand. The arm positions were selected to systematically vary the height of the centre of mass (COM) keeping imposed moments constant and vice versa. EMG was recorded bilaterally with fine-wire intramuscular electrodes from TrA and obliquus internus (OI) and with surface electrodes from rectus abdominis (RA) and erector spinae (ES). Intra-abdominal pressure (IAP) was measured via a pressure transducer in the gastric ventricle. TrA was the only muscle that displayed activation co-varying with the vertical position of the COM. Further, TrA activation increased, together with IAP and ES activation, with imposed flexion moment, i.e. with arms extended horizontally forward. In contrast to OI, RA and ES, TrA activation was independent of the direction of the imposed moment (arms held inclined forward or backward). In conclusion, TrA activation level is uniquely associated with increased postural demand caused by elevated COM. Also, TrA appears to assist in counteracting trunk flexion via increased IAP, and contribute to general spine stabilization when the trunk is exposed to moderate flexion and extension moments.

  • 13.
    Crommert, Martin Eriksson
    et al.
    Örebro University.
    Bjerkefors, Anna
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Tarassova, Olga
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Ekblom, Maria M
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Abdominal Muscle Activation During Common Modifications of the Trunk Curl-Up Exercise.2021In: Journal of Strength and Conditioning Research, ISSN 1064-8011, E-ISSN 1533-4287, Vol. 35, no 2, p. 428-435Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to investigate effects of common modifications of trunk curl-up exercise on the involvement of the abdominal muscles, particularly the deepest muscle layer, transversus abdominis (TrA). Ten healthy females performed five different variations of the trunk curl-up at a standardized speed, varying the exercise by assuming three different arm positions and applying left and right twist. Indwelling fine-wire electromyography (EMG) electrodes were used to record from TrA, obliquus internus (OI), obliquus externus (OE) and rectus abdominis (RA) unilaterally on the right side. Increasing the load by changing the arm position during a straight trunk curl-up increased the EMG of all abdominal muscles. OI and TrA showed higher activation during right twist compared to left twist whereas OE displayed the opposite pattern. RA did not show any change in activation level between twisting directions. The apparent load dependency on the activation level of all muscles and the twisting direction dependency of all muscles except RA are in keeping with the fiber orientation of the muscles. Notably, also TrA, with a less obvious mechanical role with regards to fiber orientation, increased activation with load during the straight trunk curl-up. However, the highest activation level of TrA during the trunk curl-up was only 40 % of a maximum contraction, thus it might not be the most suitable strength training exercise for this muscle.

  • 14.
    da Silva, Julio Cézar Lima
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. Karolinska institutet.
    Tarassova, Olga
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Andersson, Eva
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. Karolinska institutet.
    Rönquist, Gustaf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Grundström, Helene
    Danderyds Hospital.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. Karolinska institutet.
    Effect of increasing workload on knee extensor and flexor muscular activity during cycling as measured with intramuscular electromyography.2018In: PLOS ONE, E-ISSN 1932-6203, Vol. 13, no 8, article id e0201014Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to describe the effect of increasing workload on individual thigh muscle activation during a 20 minute incremental cycling test. Intramuscular electromyographic signals were recorded from the knee extensors rectus femoris, vastus lateralis, vastus medialis and vastus intermedius and the knee flexors semimembranosus, semitendinosus, and the short and long heads of the biceps femoris during increasing workloads. Mean activation levels were compared over the whole pedaling cycle and the crank angles at which onset and offset of activation and peak activity occurred were identified for each muscle. These data were compared between three workloads. EMG activation level significantly increased (p<0.05) with increasing workload in the rectus femoris, vastus medialis, vastus lateralis, vastus intermedius, biceps femoris long head, semitendinosus and semimembranosus but not in the biceps femoris short head. A significant change in activation timing was found for the rectus femoris, vastus lateralis, vastus medialis and semitendinosus. Of the knee flexors only the short head of the biceps femoris had its peak activity during the upstroke phase at the two highest workloads indicating a unique contribution to knee flexion.

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  • 15.
    da Silva, Julio Cézar Lima
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Tarassova, Olga
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Andersson, Eva
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Rönquist, Gustaf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Quadriceps and hamstring muscle activity during cycling as measured with intramuscular electromyography.2016In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 116, no 9, p. 1807-1817Article in journal (Refereed)
    Abstract [en]

    PURPOSE: The aim of this study was to describe thigh muscle activation during cycling using intramuscular electromyographic recordings of eight thigh muscles, including the biceps femoris short head (BFS) and the vastus intermedius (Vint).

    METHODS: Nine experienced cyclists performed an incremental test (start at 170 W and increased by 20 W every 2 min) on a bicycle ergometer either for a maximum of 20 min or to fatigue. Intramuscular electromyography (EMG) of eight muscles and kinematic data of the right lower limb were recorded during the last 20 s in the second workload (190 W). EMG data were normalized to the peak activity occurring during this workload. Statistical significance was assumed at p ≤ 0.05.

    RESULTS: The vastii showed a greater activation during the 1st quadrant compared to other quadrants. The rectus femoris (RF) showed a similar activation, but with two bursts in the 1st and 4th quadrants in three subjects. This behavior may be explained by the bi-articular function during the cycling movement. Both the BFS and Vint were activated longer than, but in synergy with their respective agonistic superficial muscles.

    CONCLUSION: Intramuscular EMG was used to verify muscle activation during cycling. The activation pattern of deep muscles (Vint and BFS) could, therefore, be described and compared to that of the more superficial muscles. The complex coordination of quadriceps and hamstring muscles during cycling was described in detail.

  • 16.
    Drake, Emma
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Ekblom, Örjan
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Kallings, Lena
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Blom, Victoria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Sport Psychology research group.
    Cardiorespiratory Fitness and Device-Measured Sedentary Behaviour are Associated with Sickness Absence in Office Workers.2020In: International Journal of Environmental Research and Public Health, ISSN 1661-7827, E-ISSN 1660-4601, Vol. 17, no 2, article id E628Article in journal (Refereed)
    Abstract [en]

    Physical activity reduces the risk of several noncommunicable diseases, and a number of studies have found self-reported physical activity to be associated with sickness absence. The aim of this study was to examine if cardiorespiratory fitness, device-measured physical activity, and sedentary behaviour were associated with sickness absence among office workers. Participants were recruited from two Swedish companies. Data on sickness absence (frequency and duration) and covariates were collected via questionnaires. Physical activity pattern was assessed using ActiGraph and activPAL, and fitness was estimated from submaximal cycle ergometry. The sample consisted of 159 office workers (67% women, aged 43 ± 8 years). Higher cardiorespiratory fitness was significantly associated with a lower odds ratio (OR) for both sickness absence duration (OR = 0.92, 95% confidence interval (CI) 0.87-0.96) and frequency (OR = 0.93, 95% CI 0.90-0.97). Sedentary time was positively associated with higher odds of sickness absence frequency (OR = 1.03, 95% CI 0.99-1.08). No associations were found for physical activity at any intensity level and sickness absence. Higher sickness absence was found among office workers with low cardiorespiratory fitness and more daily time spent sedentary. In contrast to reports using self-reported physical activity, device-measured physical activity was not associated with sickness absence.

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  • 17.
    Eftestøl, Einar
    et al.
    University of Oslo, Norway.
    Psilander, Niklas
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Cumming, Kristoffer Toldnes
    Norwegian School of Sport Sciences, Norway..
    Juvkam, Inga
    University of Oslo, Norway.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Sunding, Kerstin
    Karolinska Institutet.
    Wernbom, Mathias
    University of Gothenburg.
    Holmberg, Hans-Christer
    Mid Sweden University.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's research group.
    Bruusgaard, Jo C
    Kristiania University College, Norway..
    Raastad, Truls
    Norwegian School of Sport Sciences, Norway.
    Gundersen, Kristian
    University of Oslo, Norway..
    Muscle memory: Are myonuclei ever lost?2020In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 128, p. 456-457Article in journal (Other academic)
  • 18.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Är du chef? Överraska mig!: Krönika2015In: Fysioterapeuten, ISSN 0016-3384, E-ISSN 0807-9277, no 4, p. 45-Article in journal (Other (popular science, discussion, etc.))
  • 19.
    Ekblom, Maria
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Blom, Victoria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Sport Psychology research group.
    Ekblom, Örjan
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Kallings, Lena
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Nooijen, Carla F J
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences.
    Fysisk aktivitet och hjärnhälsa2018In: Fysioterapi, ISSN 1653-5804, no 5, p. 32-35Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

    Psykisk ohälsa är den vanligaste orsaken till sjukskrivning. Fysisk aktivitet kan förebygga många former av ohälsa, men vilka fysiska aktivitetsmönster som gynnar psykisk hälsa och kognitiva förmågor är fortfarande okänt. Denna typ av forskning är komplex och kräver samarbete med många olika aktörer i samhället.

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  • 20.
    Ekblom, Maria
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. Karolinska Institutet.
    Bojsen-Möller, Emil
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Tarassova, Olga
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Ekblom, Örjan
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Day-to day variations in physical activity patterns affect corticospinal excitability on the following day2019In: Brain Stimulation March-April 2019, vol 12, issue 2, Elsevier, 2019, Vol. 12, no 2, p. 468-, article id 437Conference paper (Other academic)
  • 21.
    Ekblom, Maria
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health. Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden..
    Bojsen-Møller, Emil
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Blom, Victoria
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health. Department of Psychology, Stockholm University, Stockholm, Sweden..
    Tarassova, Olga
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Pontén, Marjan
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Wang, Rui
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Ekblom, Örjan
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Acute effects of physical activity patterns on plasma cortisol and brain-derived neurotrophic factor in relation to corticospinal excitability.2022In: Behavioural Brain Research, ISSN 0166-4328, E-ISSN 1872-7549, Vol. 430, article id 113926Article in journal (Refereed)
    Abstract [en]

    Brain-derived neurotrophic factor (BDNF) and cortisol are both capable of modulating synaptic plasticity, but it is unknown how physical activity-induced changes in their plasma levels relate to corticospinal plasticity in humans. Sixteen inactive middle-aged men and women participated in three separate interventions consisting of 3hours prolonged sitting (SIT); 3hours sitting interrupted every 30minutes with frequent short physical activity breaks (FPA); and 2.5hours prolonged sitting followed by 25minutes of moderate intensity exercise (EXE). These 3hour sessions were each followed by a 30min period of paired associative stimulation over the primary motor cortex (PAS). Blood samples were taken and corticospinal excitability measured at baseline, pre PAS, 5min and 30min post PAS. Here we report levels of plasma BDNF and cortisol over three activity conditions and relate these levels to previously published changes in corticospinal excitability of a non-activated thumb muscle. There was no interaction between time and condition in BDNF, but cortisol levels were significantly higher after EXE compared to after SIT and FPA. Higher cortisol levels at pre PAS predicted larger increases in corticospinal excitability from baseline to all subsequent time points in the FPA condition only, while levels of BDNF at pre PAS did not predict such changes in any of the conditions. Neither BDNF nor cortisol modified changes from pre PAS to the subsequent time points, suggesting that the increased corticospinal excitability was not mediated though an augmented effect of the PAS protocol. The relationship between cortisol and plasticity has been suggested to be U-shaped. This is possibly why the moderately high levels of cortisol seen in the FPA condition were positively associated with changes AURC, while the higher cortisol levels seen after EXE were not. A better understanding of the mechanisms for how feasible physical activity breaks affect neuroplasticity can inform the theoretical framework for how work environments and schedules should be designed. DATA AVAILABILITY: Data are available from the corresponding author upon reasonable request.

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  • 22.
    Ekblom, Maria
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. Karolinska institutet.
    Ekblom, Örjan
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Börjesson, Mats
    University of Gothenburg.
    Bergström, Göran
    University of Gothenburg.
    Jern, Christina
    University of Gothenburg.
    Wallin, Anders
    University of Gothenburg.
    Device-Measured Sedentary Behavior, Physical Activity and Aerobic Fitness Are Independent Correlates of Cognitive Performance in Healthy Middle-Aged Adults-Results from the SCAPIS Pilot Study.2019In: International Journal of Environmental Research and Public Health, ISSN 1661-7827, E-ISSN 1660-4601, Vol. 16, no 24, article id E5136Article in journal (Refereed)
    Abstract [en]

    High aerobic fitness, more moderate to vigorous physical activity (MVPA) and less sedentary behavior (SED) have all been suggested to promote cognitive functions, but it is unclear whether they are independent predictors of specific cognitive domains. This study aimed to investigate to what extent aerobic fitness MVPA and SED are independently associated with cognitive performance among middle-aged Swedish adults. We acquired device-based measures of aerobic fitness, cognitive performance and percent daily time spent in MVPA and SED in Swedish adults (n = 216; 54-66 years old). Aerobic fitness was associated with better performance at one out of two tests of speed/attention and one out of four tests of executive attention, and with worse performance at one of seven tests of memory. Increasing %MVPA was associated with better performance at one out of seven tests of memory and two out of three tests of verbal ability, whereas increasing %SED was associated with better performance at all four tests of executive attention and four out of seven tests of memory. These findings suggest that aerobic fitness, %MVPA and %SED are partly independent correlates of cognitive performance. To fully understand the association between SED and performance at several tests of cognitive function, future investigations might attempt to investigate intellectually engaging SED (such as reading books) separately from mentally undemanding SED (such as watching TV).

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  • 23.
    Ekblom, Maria
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health. Institutionen för Neurovetenskap, KI.
    Ekblom, Örjan
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Nyberg, Gisela
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Selinus, Eva Noren
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Fysisk aktivitet och hjärnhälsa: En bok för skolan2021 (ed. 1)Book (Other (popular science, discussion, etc.))
    Abstract [sv]

    Fysisk aktivitet gynnar förutsättningarna för lärande och psykiskt välbefinnande, men ungdomar rör sig mindre än någonsin och fysisk aktivitet har blivit allt mer av en klassfråga. Detta har lett till orättvisa villkor för barns hälsa och lärande, en orättvisa som skolan kan bidra till att jämna ut.

    Boken Fysisk aktivitet och hjärnhälsa går konkret igenom hur skolor kan främja fysisk aktivitet inom ramen för skolvardagen och vilka effekter detta kan ge. Här beskrivs vad vi idag faktiskt vet om sambanden mellan fysisk aktivitet och hjärnhälsa med fokus på barn och ungdomar, men också vad vi behöver mer kunskap om. Med ett kritiskt förhållningssätt gör författarna en evidensbaserad genomgång av centrala begrepp inom området fysisk aktivitet med koppling till effekter på hjärnhälsa och lärande.

    Barn och ungdomar i skolåldern bör röra sig minst 60 minuter om dagen och eftersom eleverna spenderar en så stor del av sin vakna tid i skolan behöver gynnsamma förutsättningar skapas i skolmiljön då inte enbart inom skolämnet Idrott och hälsa.

    Fysisk aktivitet och hjärnhälsa vänder sig till alla lärare, lärarstudenter, skolledare och elevhälsoteam som vill bidra till ökad fysisk aktivitet, hjärnhälsa och goda vanor för livet.

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  • 24.
    Ekblom, Maria
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Ekblom, Örjan
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Wiklund, Camilla
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Wang, Rui
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Environmental and genetic contributions to device-based measures of physical activity in Swedish 9-year-olds.2023Conference paper (Other academic)
    Abstract [en]

     

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  • 25.
    Ekblom, Maria
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Hillman, Charles
    Northeastern University, USA.
    Rattray, Ben
    University of Canberra, Australia.
    Physical activity for cognitive health across the lifespan: when, what and how?2023Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    Physical activity for cognitive health across the lifespan: when, what and how?

    Physical activity appears crucial to wellbeing, and is commonly linked to our physical health. Increasingly however, physical activity is acknowledged to also play a crucial role for mental, cognitive, and brain health throughout the lifespan. Speakers in this session will address the role of physical activity across three broad life stages, childhood, adulthood and older age. The session will present the evidence around physical activity for cognitive and brain health, and considerations for what and how physical activity can be delivered for optimal outcomes at different life stages.

    Physical activity may benefit mental, cognitive, and brain health through several mechanisms. Reducing potential harm through chronic disease reduction, transiently improving mood via alterations at the cellular and molecular levels, providing a means for skill development and social interaction, and bathing the brain in a rich neurotropic environment are the main means through which cognitive benefits from physical activity are proposed.

    The impact of physical activity on cognitive and brain function can be also considered from both an acute and chronic perspective. Beneficial chronic adaptations may come from the repeated exposure to positive acute physical activity responses, but how should physical activity be dosed for these important long-term benefits? This session will provide the latest updates in the area and suggest future directions for the field to emerge.

    Speaker 1

    Title:  Physical activity effects on cognitive and brain health in school age children Speaker Last Name: HillmanSpeaker First Name: CharlesSex: MaleAcademic title: ProfessorUniversity: Northeastern UniversityDepartment: Psychology; Physical Therapy, Movement, & Rehabilitation SciencesCountry: USAEmail: c.hillman@northeastern.edu

    Physical activity (PA) can improve physical, mental, cognitive, and brain health throughout the lifespan. During childhood, the benefits of PA for cognitive and brain health have been increasingly studied, with evidence indicating enhanced executive function and improved academic performance, along with adaptations to underlying brain structure and function in specific regions and networks that support these aspects of cognition. Such findings are especially relevant given that there is a growing public health burden of unhealthy behaviors (e.g., physical inactivity, excessive energy intake) among children of industrialized nations. In recent years, children have become increasingly inactive, leading to concomitant increases in the prevalence of being overweight and unfit. Poor PA behaviors during childhood often track throughout life and have implications for the prevalence of several chronic diseases during adulthood. Particularly troubling is the absence of public health concern for the effect of physical inactivity on cognitive and brain health. It is curious that this has not emerged as a larger societal issue, given its clear relation to childhood obesity and other health disorders that have captured public attention. 

    Relative to cognitive and brain health, the literature has predominantly focused on preadolescent children, with a comparatively smaller body of evidence in preschool age and adolescent children. Such a contrast is even more striking relative to the use of neuroimaging tools to assess PA on brain health. To date, the vast majority of neuroimaging studies have investigated preadolescent children, using electroencephalography and functional magnetic resonance imaging, and found that PA and aerobic fitness benefit neural structures and networks that support executive function and memory, including the prefrontal cortex and hippocampus. Such findings have been linked to cognitive outcomes including aspects of executive function such as inhibition, working memory, and mental flexibility as well as other cognitive outcomes including relational memory and academic achievement.

    Despite evidence that PA promotes cognitive and brain health during development, a growing number of schools have minimized PA opportunities across the school day. Accordingly, this generation of children have become increasingly inactive, contributing to public health and educational concerns. By dedicating time to active play, sports, physical education, and other forms of PA, children are best-positioned to thrive in both the physical and cognitive domains. Such discoveries are timely and important for public health concerns related to chronic disease prevention as a function of childhood inactivity and obesity. These findings link pervasive societal concerns with brain health and cognition, and have implications for the educational environment and the context of learning.

    Speaker 2

    Title:  Building a cognitive reserve during adulthood: what is the prescription? Speaker Last Name: RattraySpeaker First Name: BenSex: MaleAcademic title: ProfessorUniversity: University of CanberraDepartment: Sport and Exercise ScienceCountry: AustraliaEmail: ben.rattray@canberra.edu.au 

    During adulthood, healthy individuals typically report few cognitive complaints. As a result, the role of physical activity in cognitive health either receives little attention or finds very few relationships. This is likely also a result of the cognitive engagement many adults have through education, vocational, and social settings. There are however observations that physical activity during adulthood does impact later life. Physical activity for cognitive health during early and middle adulthood therefore focuses on general health, reducing the potential harm to brain structures and processes that are associated with several lifestyle-related diseases.

    Outside of reducing harm through physical health, physical activity may play a crucial role in building a cognitive reserve, potentially improving cognitive performance, but importantly protecting against later-life declines. Taking advantage of physical activity benefits, such as increases in cerebral blood flow and neurotrophic factors, offers an opportunity to maximise neural plasticity. In this session optimising the dose characteristics of physical activity will be discussed.

    Interventions that specifically attempt to take advantage of plasticity-supporting physical activity are those that ensure cognitive activity is in close temporal proximity. Sequentially- or concurrently-programming physical exercise with a cognitive intervention are gaining popularity, with most evidence currently in older adults. This session will provide an update on the latest evidence for concurrent training in healthy adulthood.

    It is hypothesized that an increased availability of factors such as brain-derived neurotrophic factor during targeted cognitive interventions improve the gains that such training can provide. However, depending on the outcome, some propose that concurrent activity may also work through the combination of effortful behaviours impacting individuals’ capacity, or tolerance for work. This fatigue-linked pathway may also impact cognitive health when engaged over longer periods, or when individuals are asked to report subjective cognitive complaints. These potential pathways will also be discussed in terms of informing the when, what, and how of physical activity interventions for cognitive health.

    Speaker 3

    Title:  How physical activity affects cognitive health in older adultsSpeaker Last Name: EkblomSpeaker First Name: MariaSex: FemaleAcademic title: ProfessorUniversity: Swedish School of Sport and Health SciencesDepartment: Physical Activity and HealthCountry: SwedenEmail: maria.ekblom@gih.se 

    There is consistent evidence to suggest that being more fit in young adulthood is associated to having better cognitive function in both young and older adulthood. We also know that being aerobically high fit is associated with having executive abilities that make it easier to attain and sustain healthy habits. While such information may be interesting, it tells us very little on whether physical activity promotion among low fit inactive individuals might have a positive influence on their future cognitive health. In midlife, lack of time is a commonly perceived barrier towards physical activity. Still, as we retire, individuals who were inactive in midlife tend to stay inactive after retiring, despite now having more spare time at hand. When preaching that it is never too late, we need to take care not to shame those whose shoes we have not walked in. Remember, that although we have all equal human value, we have different opportunities, both genetically and in terms of socioeconomic circumstances. 

    When we compare the brain health of senior athletes to that of their less active peers, this is not helping anyone. That is why I prefer randomized controlled trials for the purpose of figuring out what type of exercise might work for whom. The Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability evaluated whether a 2-year multicomponent intervention with exercise, cognitive training, diet and vascular risk monitoring could slow down the cognitive decline in an at-risk population. They show that such intervention actually can have small effects on the trajectories of cognitive decline, but we are still not close to understanding what the active component is. Large scale exercise RCTs using advanced neuroimaging to investigate neurophysiological mechanisms are under way, but these are very expensive. Major breakthroughs in plasma biomarkers of neurodegenerative disease progression have been exposed recently. Such new techniques should be exploited in future RCTs by researchers who want to investigate if support to increased physical activity can really change the cognitive trajectories of physically inactive individuals who want to spare their brain health. This presentation will explore our current understanding of how and physical activity affects cognitive health in older adults and suggest new avenues of exploration.

  • 26.
    Ekblom, Maria M
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Gago, Paulo
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Post activation potentiation of the plantar flexors at different knee angles2013Conference paper (Refereed)
  • 27.
    Ekblom, Maria M Nordlund
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Thorstensson, Alf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Effects of prolonged vibration on H-reflexes, muscle activation, and dynamic strength.2011In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 43, no 10, p. 1933-9Article in journal (Refereed)
    Abstract [en]

     Neural activation is generally lower during maximal voluntary lengthening compared with shortening and isometric muscle actions, but the mechanisms underlying these differences are unclear. In maximal voluntary isometric actions, reduced Ia-afferent input induced by prolonged tendon vibration has been shown to impair neural activation and strength.

    PURPOSE: This study aimed to investigate whether reducing Ia-afferent input influences neural activation in maximal voluntary dynamic muscle actions and, if so, whether it affects shortening and lengthening muscle actions differently.

    METHODS: Eight women participated in three familiarization sessions and two randomly ordered experiments. In one experiment, 30-min vibration at 100 Hz was applied to the Achilles tendon to decrease Ia-afferent input as measured by the H-reflex. In the control experiment, rest substituted the vibration. Root mean square EMG from plantar and dorsiflexor muscles and plantar flexor strength were measured during maximal voluntary plantar flexor shortening and lengthening actions (20°·s(-1)) before and after vibration and rest, respectively. Soleus H-reflexes and M-waves were elicited before each set of strength tests.

    RESULTS: The vibration caused a decrease in H-reflex amplitude by, on the average, 33%, but root mean square EMG and plantar flexor strength remained largely unaffected in both action types.

    CONCLUSIONS: The findings suggest that Ia-afferent input may not substantially contribute to maximal voluntary dynamic muscle strength of the plantar flexor muscles, as tested here, and thus, the results do not support the notion that Ia-afferent excitation would contribute differently to neural activation in maximal voluntary lengthening and shortening muscle actions.

  • 28.
    Ekblom, Maria
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Ovendal, Alexander
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Tais, Senna
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Halvorsen, Kjartan
    KTH.
    Eriksson, Martin
    KTH.
    Acute effects of concurrent EMG feedback on knee extensor strength and activation2012Conference paper (Refereed)
  • 29.
    Ekblom, Örjan
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Relations between motor proficiency and sub-components of physical activity in children2012In: Be active 2012 Abstracts: Supplement to Journal of Science and Medicine in Sport 15(6):77. Dec 2012, 2012, p. 77-Conference paper (Refereed)
  • 30. Eriksson Crommert, Martin
    et al.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Thorstensson, Alf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Motor control of the trunk during a modified clean and jerk lift.2014In: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 24, no 5, p. 758-763Article in journal (Refereed)
    Abstract [en]

    The purpose of the present study was to investigate the pattern of trunk muscle activation and intra-abdominal pressure (IAP) in a somewhat modified version of the clean and jerk lift. Nine healthy physically active male amateurs performed the exercise with a 30-kg barbell. Muscle activity was registered with electromyography from transversus abdominis (TrA) and obliquus internus (OI) using intramuscular electrodes and from rectus abdominis (RA) and erector spinae (ES) with surface electrodes. IAP was recorded with a nasogastric catheter. Measurements were made in various static positions throughout the lift and in the transitional phases separating them, both during lifting and lowering. The results demonstrated that the innermost abdominal muscle, TrA, showed increased activation levels in the two highest positions, whereas ES was most active, together with the highest IAP, in the lowest position. OI and RA showed generally little activation and no obvious trend throughout the lift. The results strengthen the view of a contributing role of TrA to the upright control of the trunk and indicate that the clean and jerk lift might constitute a whole-body exercise, still targeting the TrA muscle, in late-stage rehabilitation, especially for athletes during return to sports.

  • 31. Eriksson Crommert, Martin
    et al.
    Halvorsen, Kjartan
    Ekblom, Maria M
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Trunk Muscle Activation at the Initiation and Braking of Bilateral Shoulder Flexion Movements of Different Amplitudes.2015In: PLOS ONE, E-ISSN 1932-6203, Vol. 10, no 11, article id e0141777Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to investigate if trunk muscle activation patterns during rapid bilateral shoulder flexions are affected by movement amplitude. Eleven healthy males performed shoulder flexion movements starting from a position with arms along sides (0°) to either 45°, 90° or 180°. EMG was measured bilaterally from transversus abdominis (TrA), obliquus internus (OI) with intra-muscular electrodes, and from rectus abdominis (RA), erector spinae (ES) and deltoideus with surface electrodes. 3D kinematics was recorded and inverse dynamics was used to calculate the reactive linear forces and torque about the shoulders and the linear and angular impulses. The sequencing of trunk muscle onsets at the initiation of arm movements was the same across movement amplitudes with ES as the first muscle activated, followed by TrA, RA and OI. All arm movements induced a flexion angular impulse about the shoulders during acceleration that was reversed during deceleration. Increased movement amplitude led to shortened onset latencies of the abdominal muscles and increased level of activation in TrA and ES. The activation magnitude of TrA was similar in acceleration and deceleration where the other muscles were specific to acceleration or deceleration. The findings show that arm movements need to be standardized when used as a method to evaluate trunk muscle activation patterns and that inclusion of the deceleration of the arms in the analysis allow the study of the relationship between trunk muscle activation and direction of perturbing torque during one and the same arm movement.

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  • 32.
    Eriksson-Crommert, Martin
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Thorstensson, Alf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Effects of arm movement amplitude on the initial trunk muscle activation pattern during raptid bilateral shoulder flexions during standing2012Conference paper (Refereed)
  • 33.
    Fernström, Maria
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Heiland, Emerald G
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health. Department of Surgical Sciences, Medical Epidemiology, Uppsala University Uppsala Sweden.
    Kjellenberg, Karin
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Pontén, Marjan
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Tarassova, Olga
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Nyberg, Gisela
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health. Department of Global Public Health, Karolinska Institutet, Stockholm, Sweden.
    Helgadóttir, Björg
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health. Division of Insurance Medicine, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health. Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
    Ekblom, Örjan
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Effects of prolonged sitting and physical activity breaks on measures of arterial stiffness and cortisol in adolescents2023In: Acta Paediatrica, ISSN 0803-5253, E-ISSN 1651-2227, Vol. 112, no 5, p. 1011-1018Article in journal (Refereed)
    Abstract [en]

    Aim

    In adults, prolonged periods of sitting have been linked to acute negative effects on vascular structure and function. The aim of this study was to evaluate the acute effects of physical activity (PA) breaks during prolonged sitting on arterial stiffness, cortisol and psychological factors in adolescents.

    Methods

    Adolescents underwent different short (3-min) breaks starting every 20 min, during 80 min of sitting on three separate days. Breaks were (A) social seated breaks (SOC), (B) low-intensity simple resistance activity PA breaks (SRA) and (C) moderate-intensity step-up PA breaks (STEP). The arterial stiffness measures were augmentation index (AIx), AIx@75 and pulse wave velocity (PWV). Cortisol was measured from saliva. Psychological factors were self-reported.

    Results

    Eleven girls and six boys (average age 13.6 ± 0.7 years) participated, with average baseline heart rates of 72 ± 11 bpm, systolic/diastolic blood pressure 111 ± 7/64 ± 6 mmHg and cortisol 10.9 ± 5.8 nmoL/L. PWV, cortisol and psychological factors did not change after any of the conditions. AIx@75 increased significantly (4.9 ± 8.7–9.2 ± 13.2) after the STEP intervention compared with SOC and SRA (time × condition p < 0.05).

    Conclusion

    Arterial stiffness increased after prolonged sitting with frequent, short step-up activity breaks. The results indicate potential important intensity-dependent effects of physical activity on vascular regulation in youth.

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  • 34.
    Frank, Per
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Research group for Mitokondriell funktion och metabolisk kontroll.
    Andersson, Eva
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Research group for Mitokondriell funktion och metabolisk kontroll.
    Pontén, Marjan
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's and Mats Börjesson's research group.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Sahlin, Kent
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Research group for Mitokondriell funktion och metabolisk kontroll.
    Strength training improves muscle aerobic capacity and glucose tolerance in elderly2016In: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 26, no 7, p. 764-773Article in journal (Refereed)
    Abstract [en]

    The primary aim of this study was to investigate the effect of short-term resistance training (RET) on mitochondrial protein content and glucose tolerance in elderly. Elderly women and men (age 71 ± 1, mean ± SEM) were assigned to a group performing 8 weeks of resistance training (RET, n = 12) or no training (CON, n = 9). The RET group increased in (i) knee extensor strength (concentric +11 ± 3%, eccentric +8 ± 3% and static +12 ± 3%), (ii) initial (0-30 ms) rate of force development (+52 ± 26%) and (iii) contents of proteins related to signaling of muscle protein synthesis (Akt +69 ± 20 and mammalian target of rapamycin +69 ± 32%). Muscle fiber type composition changed to a more oxidative profile in RET with increased amount of type IIa fibers (+26.9 ± 6.8%) and a trend for decreased amount of type IIx fibers (-16.4 ± 18.2%, P = 0.068). Mitochondrial proteins (OXPHOS complex II, IV, and citrate synthase) increased in RET by +30 ± 11%, +99 ± 31% and +29 ± 8%, respectively. RET resulted in improved oral glucose tolerance measured as reduced area under curve for glucose (-21 ± 26%) and reduced plasma glucose 2 h post-glucose intake (-14 ± 5%). In CON parameters were unchanged or impaired. In conclusion, short-term resistance training in elderly not only improves muscular strength, but results in robust increases in several parameters related to muscle aerobic capacity.

  • 35.
    Gago, Paulo
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. Karolinska Institutet.
    Marques, Mário C.
    University of Beira Interior (UBI), Covilhã, Portugal.
    Marinho, Daniel A.
    University of Beira Interior (UBI), Covilhã, Portugal.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Effects of post activation potentiation on electromechanical delay2019In: Clinical Biomechanics, ISSN 0268-0033, E-ISSN 1879-1271, Vol. 70, p. 115-122Article in journal (Refereed)
    Abstract [en]

    Electromechanical delay (EMD) presumably depends upon both contractile and tensile factors. It has recently been used as an indirect measure of muscle tendon stiffness to study adaptations to stretching and training. The aim of the present study was to investigate whether contractile properties induced by a 6 s maximum voluntary isometric contraction (MVIC) could affect EMD without altering passive muscle tendon stiffness or stiffness index. Plantar flexor twitches were evoked via electrical stimulation of the tibial nerve in eight highly trained male sprinters before and after a 6 s MVIC in passive isometric or passively shortening or lengthening muscles. For each twitch, EMD, twitch contractile properties and SOLM-Wave were measured. Passive muscle tendon stiffness was measured from the slope of the relation between torque and ankle angle during controlled passive dorsal flexion and stiffness index by curve-fitting the torque angle data using a second-order polynomial function. EMD did not differ between isometric, lengthening or shortening movements. EMD was reduced by up to 11.56 ± 5.64% immediately after the MVIC and stayed depressed for up to 60 s after conditioning. Peak twitch torque and rate of torque development were potentiated by up to 119.41 ± 37.15% and 116.06 ± 37.39%, respectively. Rising time was reduced by up to 14.46 ± 7.22%. No significant changes occurred in passive muscle tendon stiffness or stiffness index. Using a conditioning MVIC, it was shown that there was an acute enhancement of contractile muscle properties as well as a significant reduction in EMD with no corresponding changes in stiffness. Therefore, caution should be taken when using and interpreting EMD as a proxy for muscle tendon stiffness.

  • 36.
    Gago, Paulo
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Tarassova, Olga
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Ekblom, Maria M
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Post activation potentiation can be induced without impairing tendon stiffness.2014In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 114, no 11, p. 2299-2308Article in journal (Refereed)
    Abstract [en]

    PURPOSE: This study aimed to investigate conditioning effects from a single 6-s plantar flexion maximal voluntary isometric contraction (MVIC) on Achilles tendon stiffness (ATS) and twitch properties of the triceps surae in athletes.

    METHODS: Peak twitch (PT), rate of torque development (RTD), rising time (RT10-90%) and half relaxation time (HRT) were measured from supramaximal twitches evoked in the plantar flexors of 10 highly trained athletes. Twitches were evoked before and at seven occasions during 10 min of recovery after a 6-s MVIC. In a second session, but at identical post-conditioning time points, ATS was measured at 30 and 50 % of MVIC (ATS30% and ATS50%) using an ultrasonography-based method.

    RESULTS: The magnitude and duration of the conditioning MVIC on muscle contractile properties were in accordance with previous literature on post activation potentiation (PAP), i.e., high potentiation immediately after MVIC, with significant PAP for up to 3 min after the MVIC. While PT and RTD were significantly enhanced (by 60.6 ± 19.3 and 90.1 ± 22.5 %, respectively) and RT10-90% and HRT were reduced (by 10.1 ± 7.7 and 18.7 ± 5.6 %, respectively) after conditioning, ATS remained unaffected.

    CONCLUSIONS: Previous studies have suggested that changes in stiffness after conditioning may interfere with the enhancements in twitch contractile properties. The present study, however, provided some evidence that twitch enhancements after a standard PAP can be induced without changes in ATS. This result may suggest that athletes can use this protocol to enhance muscle contractile properties without performance deficits due to changes in ATS.

  • 37.
    Gago, Paulo
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences. Research Center for Sport, Health and Human Development, (CIDESD), Portugal.
    Arndt, Toni
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. Department of CLINTEC, Karolinska Institutet, Stockholm.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences. Department of Neuroscience, Karolinska Institutet, Stockholm.
    Post Activation Potentiation of the Plantarflexors: Implications of Knee Angle Variations2017In: Journal of Human Kinetics, ISSN 1640-5544, E-ISSN 1899-7562, Vol. 57, p. 29-38Article in journal (Refereed)
    Abstract [en]

    Flexing the knee to isolate the single joint soleus from the biarticular gastrocnemius is a strategy forinvestigating individual plantarflexor's post activation potentiation (PAP). We investigated the implications of testingplantarflexor PAP at different knee angles and provided indirect quantification of the contribution of gastrocnemiuspotentiation to the overall plantarflexor enhancements post conditioning. Plantarflexor supramaximal twitches weremeasured in ten male power athletes before and after a maximal isometric plantarflexion (MVIC) at both flexed andextended knee angles. Mean torque and soleus (SOLRMS) and medial gastrocnemius (MGRMS) activity were measuredduring the MVIC. The mean torque and MGRMS of the MVIC were lower (by 33.9 and 42.4%, respectively) in the flexedcompared to the extended position, with no significant difference in SOLRMS. After the MVIC, twitch peak torque (PT)and the rate of torque development (RTR) potentiated significantly more (by 17.4 and 14.7% respectively) in theextended as compared to the flexed knee position, but only immediately (5 s) after the MVIC. No significant differenceswere found in the twitch rate of torque development (RTD) potentiation between positions. It was concluded that kneejoint configuration should be taken into consideration when comparing studies of plantarflexor PAP. Furthermore,results reflect a rather brief contribution of the gastrocnemius potentiation to the overall plantarflexor twitchenhancements.

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  • 38.
    Gago, Paulo
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Arndt, Toni
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Tarassova, Olga
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Post activation potentiation electromechanical delay and achilles tendon stiffness in athletes2014Conference paper (Refereed)
  • 39.
    Gago, Paulo
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Arndt, Toni
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Tarrassova, Olga
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Post activation potentiation and Achilles tendon stiffness in power athletes2013Conference paper (Refereed)
  • 40.
    Gago, Paulo
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Marques, Mario
    Research Center for Sport, Health and Human Development, University of Beira Interior (UBI/CIDESD), Covilhã,.
    Marinho, Daniel
    Research Center for Sport, Health and Human Development, University of Beira Interior (UBI/CIDESD), Covilhã,.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Passive muscle length changes affects twitch potentiation in power athletes2012In: 8th International Conference on Strength Training: Book of abstracts / [ed] Håvard Wiig et al, 2012, p. 212-213Conference paper (Refereed)
  • 41.
    Gago, Paulo
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Marques, Mário C
    Marinho, Daniel A
    Ekblom, Maria M
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Passive Muscle Length Changes Affect Twitch Potentiation in Power Athletes.2014In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 46, no 7, p. 1334-1342Article in journal (Refereed)
    Abstract [en]

    INTRODUCTION: A conditioning maximal voluntary muscle action (MVC) has been shown to induce post-activation potentiation, i.e. improved contractile muscle properties, when muscles are contracted isometrically. It is still uncertain how the contractile properties are affected during ongoing muscle length changes. The purpose of this study was to investigate the effects of a 6 s conditioning MVC on twitch properties of the plantar flexors during ongoing muscle length changes.

    METHODS: Peak twitch, rate of torque development (RTD) and relaxation (RTR), rising time and half relaxation time (HRT) were measured from supramaximal twitches evoked in the plantar flexors of 11 highly trained athletes. Twitches were evoked prior to a 6 s MVC and subsequently on 8 different occasions during a 10-minute recovery, for five different modes: fast lengthening, slow lengthening, isometric, fast shortening and slow shortening of the plantar flexors.

    RESULTS: The magnitude and duration of effects from the conditioning MVC were significantly different between modes. Peak twitch, RTD and RTR significantly increased for all modes but more so for twitches evoked during fast and slow shortening as compared to lengthening. Rising time was reduced in the lengthening modes, but slightly prolonged in the shortening modes. HRT was significantly reduced for all modes except fast lengthening.

    CONCLUSION: The findings show that the effects of a conditioning MVC on twitch contractile properties are dependent on direction and velocity of ongoing muscle length changes. This may imply that functional enhancements from a conditioning MVC might be expected to be greatest for concentric muscle actions, but are still present in isometric and eccentric parts of a movement.

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  • 42.
    Gago, Paulo
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences.
    Zoellner, Anja
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences.
    Cezar, Julio
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Ekblom, Maria M
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Post Activation Potentiation and Concentric Contraction Performance: Effects on Rate of Torque Development, Neuromuscular Efficiency and Tensile Properties.2020In: Journal of Strength and Conditioning Research, ISSN 1064-8011, E-ISSN 1533-4287, Vol. 34, no 6, p. 1600-1608Article in journal (Refereed)
    Abstract [en]

    This study investigated how a 6s maximal voluntary isometric conditioning contration (MVIC) affected plantar flexor twitch rate of torque development (RTDTW), as well as peak torque (PTCC) and rate of torque development (RTDCC) of maximal voluntary concentric contractions (MVCC) performed at 60°/s. RTDCC and normalized triceps surae electromyography signals (EMGTS) were measured during different phases of contraction. Additionally, muscle tendon unit passive stiffness index (SI) calculated from the torque-angle relation was measured following each MVCC.Enhancements were found in the RTDTW immediately (by 59.7%) and up to 480s (by 6.0%) post MVIC (p<0.05). RTDCC during the 100-200ms, 50-200ms, and 0-200ms phases and PTCC were enhanced (by 5.7-9.5%) from 90-300s post conditioning (p<0.05). Neuromuscular efficiency increased (decreased EMGTS/RTDCC) in the 50-200ms and 0-200ms phases by 8.8-12.4%, from 90-480s post MVIC (p<0.05). No significant changes were found in the SI or in RTDCC during the 50-100ms phase, suggesting that the enhancements reported, reflect mainly contractile rather than neural or tensile mechanisms.PAP effects on PTCC and RTDCC were significant, and more durable at a lower velocity than previously reported. Enhancement in RTDCC and neuromuscular efficiency were found to be more prominent in later phases (>100ms) of the MVCC. This suggests that enhanced contractile properties, attained via MVIC, benefit concentric contraction performance.

  • 43.
    Godhe, Manne
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health. Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden.
    Ekblom, Örjan
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Pontén, Marjan
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Andersson, Eva
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health. Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden.
    Improved accelerometer assessed physical activity patterns after an eight-week exercise intervention.2021Conference paper (Refereed)
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    Godhe et al. 2021
  • 44.
    Godhe, Manne
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Ekblom, Örjan
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. Karolinska Institutet.
    Pontén, Marjan
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Andersson, Eva
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. Karolinska Institutet.
    Improved daily movement patterns in an accelerometer-assessed 8-weeks exercise project in older adults2019In: British Journal of Sports Medicine Vol 53, suppl 1, BMJ Publishing Group Ltd, 2019, Vol. 53, p. A2-Conference paper (Other academic)
  • 45.
    Godhe, Manne
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Ekblom, Örjan
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Pontén, Marjan
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Kallings, Lena
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Andersson, Eva
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Fysiska aktivitetsmönster hos äldre vuxna före och efter en ledarledd träningsperiod - en accelerometerstudie2021In: Svensk idrottsmedicin 2021:3, Svensk förening för fysisk aktivitet och idrottsmedicin , 2021, p. 36-37Conference paper (Other academic)
  • 46.
    Heiland, Emerald G
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Ekblom, Örjan
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Bojsen-Møller, Emil
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Larisch, Lisa-Marie
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Blom, Victoria
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Bi-Directional, Day-to-Day Associations between Objectively-Measured Physical Activity, Sedentary Behavior, and Sleep among Office Workers.2021In: International Journal of Environmental Research and Public Health, ISSN 1661-7827, E-ISSN 1660-4601, Vol. 18, no 15, article id 7999Article in journal (Refereed)
    Abstract [en]

    The bi-directional, day-to-day associations between daytime physical activity and sedentary behavior, and nocturnal sleep, in office workers are unknown. This study investigated these associations and whether they varied by weekday or weekend day. Among 324 Swedish office workers (mean age 42.4 years; 33.3% men), moderate-to-vigorous physical activity (MVPA), and sedentary behaviors and sleep (total sleep time (TST) and sleep efficiency (SE)) were ascertained by using accelerometers (Actigraph GT3X) over 8 days. Multilevel linear mixed models were used to assess the bi-directional, day-to-day, within-person associations. Additional analyses stratified by weekend/weekday were performed. On average, participants spent 6% (57 min) of their day in MVPA and 59% (9.5 h) sedentary, and during the night, TST was 7 h, and SE was 91%. More daytime sedentary behavior was associated with less TST that night, and reciprocally, more TST at night was associated with less sedentary behavior on the following weekday. Greater TST during the night was also associated with less MVPA the next day, only on weekdays. However, daytime MVPA was not associated with TST that night. Higher nighttime SE was associated with greater time spent sedentary and in MVPA on the following day, regardless if weekday or weekend day. Sleep may be more crucial for being physically active the following day than vice versa, especially on weekdays. Nevertheless, sedentary behavior's relation with sleep time may be bi-directional. Office workers may struggle with balancing sleep and physical activity time.

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  • 47.
    Heiland, Emerald G
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences.
    Ekblom, Örjan
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Tarassova, Olga
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Fernström, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    English, Coralie
    University of Newcastle, NSW, Australia..
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    ABBaH: Activity Breaks for Brain Health: A Protocol for a Randomized Crossover Trial2020In: Frontiers in Human Neuroscience, E-ISSN 1662-5161, Vol. 14, article id 273Article in journal (Refereed)
    Abstract [en]

    Introduction: Extended periods of sitting may have detrimental effects on brain health. However, the effects of breaking up prolonged sedentary periods with frequent, short physical activity bouts on mechanisms to improve brain health remain unclear. Therefore, this study aims to investigate the immediate effects of uninterrupted sitting and frequent, short bouts of physical activity on cerebral blood flow and cognitive function in the prefrontal cortex in middle-aged adults. Methods: This is a protocol article to describe a randomized crossover study. We will collect data from 13 healthy adults, aged between 40 and 60 years old, with a body mass index <35 kg/m(2). Participants will be required to come into the laboratory on three occasions, sit for 3 h, and perform a different type of break for 3 min every 30 min at each visit in a random order, being either: (1) a social break; (2) brisk walk on a treadmill; or (3) simple resistance activities. Before and after each experimental condition, cerebral blood flow (primary outcome) will be measured using functional near-infrared spectroscopy (fNIRS), with short-separation channels, and working memory (1-, 2-, and 3-back on the computer) will be assessed. The following additional secondary outcomes will be collected: psychological factors (questionnaires); arterial stiffness; salivary cortisol levels; and blood glucose levels. Conclusion: The results from this randomized crossover study will determine the effects of uninterrupted sitting and frequent, short bouts of physical activity on cerebral blood flow and cognitive performance. Publication of this study protocol emphasizes the importance of registration and publication of protocols in the field of sedentary behavior research.

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  • 48.
    Heiland, Emerald G
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health. Uppsala University, Sweden.
    Kjellenberg, Karin
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Tarassova, Olga
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Fernström, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Nyberg, Gisela
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health. Karolinska institutet, Stockholm, Sweden.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health. Karolinska institutet, Stockholm, Sweden.
    Helgadóttir, Björg
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health. Karolinska institutet, Stockholm, Sweden.
    Ekblom, Örjan
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    ABBaH teens: Activity Breaks for Brain Health in adolescents2022In: Trials, E-ISSN 1745-6215, Vol. 23, no 1, article id 22Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Physical activity breaks are widely being implemented in school settings as a solution to increase academic performance and reduce sitting time. However, the underlying physiological mechanisms suggested to improve cognitive function from physical activity and the frequency, intensity, and duration of the breaks remain unknown. This study will investigate the effects of frequent, short physical activity breaks during prolonged sitting on task-related prefrontal cerebral blood flow, cognitive performance, and psychological factors. Additionally, the moderating and mediating effects of arterial stiffness on changes in cerebral blood flow will be tested.

    METHODS: This is a protocol for a randomized crossover study that will recruit 16 adolescents (13-14 years old). Participants will undergo three different conditions in a randomized order, on three separate days, involving sitting 80 min with a different type of break every 17 min for 3 min. The breaks will consist of (1) seated social breaks, (2) simple resistance activities, and (3) step-up activities. Before and after the 80-min conditions, prefrontal cerebral blood flow changes will be measured using functional near-infrared spectroscopy (primary outcome), while performing working memory tasks (1-, 2-, and 3-back tests). Arterial stiffness (augmentation index and pulse wave velocity) and psychological factors will also be assessed pre and post the 80-min interventions.

    DISCUSSION: Publication of this protocol will help to increase rigor in science. The results will inform regarding the underlying mechanisms driving the association between physical activity breaks and cognitive performance. This information can be used for designing effective and feasible interventions to be implemented in schools.

    TRIAL REGISTRATION: www.ClinicalTrials.gov , NCT04552626 . Retrospectively registered on September 21, 2020.

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  • 49.
    Heiland, Emerald G.
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Kjellenberg, Karin
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Tarassova, Olga
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Nyberg, Gisela
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Ekblom, Örjan
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Helgadóttir, Björg
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Acute effects of nitrate and breakfast on working memory and cerebral blood flow in adolescents: a randomized crossover trial2023Conference paper (Other academic)
    Abstract [en]

    Purpose: Beneficial acute effects of dietary nitrate have been demonstrated on working memory in adults, with changes in cerebral blood flow (CBF) being a potential mechanism. However, these effects have not been studied in adolescents. Moreover, having breakfast compared to skipping may also exhibit positive effects on working memory. Therefore, this randomized crossover trial investigated the acute effects of nitrate and breakfast on working memory and changes in task-related CBF in adolescents.  Methods: This trial will recruit at least 43 adolescents (13–15 years old). There were three experimental breakfast conditions: (1) none, (2) regular, and (3) regular breakfast with high nitrate in the form of concentrated beetroot juice. Working memory (1-, 2-, 3-back tests) and task-related CBF (prefrontal cortex oxygenated and deoxygenated-hemoglobin changes estimated using functional near-infrared spectroscopy) were measured immediately after breakfast and 130 min later. The data collection for this study is ongoing, thus results for 35 adolescents are presented here and due to blinding of the researcher we are unable to report at this time in which condition these effects occurred, but will be revealed by the time of the conference, as well as for the results on changes in CBF.  Results: Preliminary results from the ongoing study showed that from pretest to posttest there was a statistically significant improvement in reaction time in all three conditions for all three n-back tests, but no intervention effects. Accuracy, however, improved from pretest to posttest in only one condition, for all three nback tests (β [95% confidence interval] from linear mixed-effects models with subject as random effect: 1-back 2.8[1.2-4.3], 2-back 2.6[0.9-4.2], 3-back 3.6[2.2-5.0]), and there was a tendency towards an intervention effect between this breakfast condition and another on the accuracy of the 3-back test (P for time-by-condition interaction 0.07).   Conclusions: The results from this study will increase our understanding into the effects of breakfast and its composition (i.e., nitrate-rich) on acutely improving working memory in adolescents and the potential mechanisms. In turn, the results will inform on whether policies on providing breakfast in schools should be considered to improve students' cognitive performance.

  • 50.
    Heiland, Emerald G
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Tarassova, Olga
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Fernström, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    English, Coralie
    School of Health Sciences and Priority Research Centre for Stroke and Brain Injury, University of Newcastle, Callaghan, NSW, Australia.; Centre for Research Excellence in Stroke Recovery and Rehabilitation, Florey Institute of Neuroscience and Hunter Medical Research Institute, Callaghan, NSW, Australia..
    Ekblom, Örjan
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health. Department of Neuroscience, Karolinska Institutet, Solna, Sweden..
    Frequent, Short Physical Activity Breaks Reduce Prefrontal Cortex Activation but Preserve Working Memory in Middle-Aged Adults: ABBaH Study.2021In: Frontiers in Human Neuroscience, E-ISSN 1662-5161, Vol. 15, article id 719509Article in journal (Refereed)
    Abstract [en]

    Prolonged sitting is increasingly common and may possibly be unfavorable for cognitive function and mood. In this randomized crossover study, the effects of frequent, short physical activity breaks during prolonged sitting on cognitive task-related activation of the prefrontal cortex were investigated. The effects on working memory, psychological factors, and blood glucose were also examined, and whether arterial stiffness moderated prefrontal cortex activation. Thirteen subjects (mean age 50.5 years; eight men) underwent three 3-h sitting conditions, interrupted every 30-min by a different 3-min break on separate, randomized-ordered days: seated social interactions (SOCIAL), walking (WALK), or simple resistance activities (SRA). Arterial stiffness was assessed at baseline. Before and after each 3-h condition, psychological factors (stress, mood, sleepiness, and alertness) were assessed through questionnaires and functional near-infrared spectroscopy (fNIRS) was used to measure changes in prefrontal oxygenated hemoglobin (Oxy-Hb), indicative of cortical activation, while performing working memory tasks [1- (baseline), 2-, and 3-back]. Blood glucose levels were continuously measured throughout the conditions. Results revealed no significant changes in Oxy-Hb during the 2-back compared with the 1-back test in any condition, and no time-by-condition interactions. During the 3-back test, there was a significant decrease in Oxy-Hb compared with the 1-back after the WALK condition in the right prefrontal cortex, but there were no time-by-condition interactions, although 3-back reaction time improved only in the WALK condition. Mood and alertness improved after the WALK condition, which was significantly different from the SOCIAL condition. Arterial stiffness moderated the effects, such that changes in Oxy-Hb were significantly different between WALK and SOCIAL conditions only among those with low arterial stiffness. Blood glucose during the interventions did not differ between conditions. Thus, breaking up prolonged sitting with frequent, short physical activity breaks may reduce right prefrontal cortex activation, with improvements in some aspects of working memory, mood, and alertness. Clinical Trial Registration:www.ClinicalTrials.gov, identifier NCT04137211.

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