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  • 1.
    Andersson, Eva A
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet. Karolinska institutet.
    Frank, Per
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet. Karolinska institutet.
    Pontén, Marjan
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet.
    Ekblom, Björn
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet, Björn Ekbloms forskningsgrupp.
    Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet. Karolinska institutet.
    Moberg, Marcus
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet.
    Sahlin, Kent
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet.
    Improving Strength, Power, Muscle Aerobic Capacity, and Glucose Tolerance through Short-term Progressive Strength Training Among Elderly People.2017Inngår i: Journal of Visualized Experiments, ISSN 1940-087X, E-ISSN 1940-087X, nr 125Artikkel i tidsskrift (Fagfellevurdert)
    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.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Nordlund Ekblom, Maria M
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Josefsson, Karin
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Thorstensson, Alf
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Deep and superficial abdominal muscle activation during trunk stabilization exercises with and without instruction to hollow.2010Inngår i: Manual Therapy, ISSN 1356-689X, E-ISSN 1532-2769, Vol. 15, nr 5, s. 502-7Artikkel i tidsskrift (Fagfellevurdert)
    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.
    Bojsen-Møller, Emil
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet.
    Boraxbekk, Carl-Johan
    Copenhagen University Hospital, Hvidovre, Denmark.
    Ekblom, Örjan
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet, Björn Ekbloms forskningsgrupp.
    Blom, Victoria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Forskningsgruppen för idrottspsykologi.
    Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC). Karolinska institutet.
    Relationships between Physical Activity, Sedentary Behaviour and Cognitive Functions in Office Workers.2019Inngår i: International Journal of Environmental Research and Public Health, ISSN 1661-7827, E-ISSN 1660-4601, Vol. 16, nr 23, artikkel-id E4721Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 4.
    Brink-Elfegoun, Thibault
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    Holmberg, Hans-Christer
    Nordlund Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Ekblom, Björn
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Björn Ekbloms forskningsgrupp.
    Neuromuscular and circulatory adaptation during combined arm and leg exercise with different maximal work loads.2007Inngår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 101, nr 5, s. 603-11Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 5. Broström, Eva
    et al.
    Nordlund Ekblom, Maria M
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Cresswell, Andrew G
    Plantar- and dorsiflexor strength in prepubertal girls with juvenile idiopathic arthritis.2004Inngår i: Archives of Physical Medicine and Rehabilitation, ISSN 0003-9993, E-ISSN 1532-821X, Vol. 85, nr 8, s. 1224-30Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 6.
    Crommert, M Eriksson
    et al.
    Örebro Universitet.
    Nordlund Ekblom, Maria M
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Thorstensson, Alf
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Activation of transversus abdominis varies with postural demand in standing.2011Inngår i: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 33, nr 3, s. 473-7Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 7.
    Crommert, Martin Eriksson
    et al.
    Örebro University.
    Bjerkefors, Anna
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Tarassova, Olga
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Ekblom, Maria M
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Abdominal Muscle Activation During Common Modifications of the Trunk Curl-Up Exercise.2018Inngår i: Journal of Strength and Conditioning Research, ISSN 1064-8011, E-ISSN 1533-4287Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 8.
    da Silva, Julio Cézar Lima
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC). Karolinska institutet.
    Tarassova, Olga
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Andersson, Eva
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC). Karolinska institutet.
    Rönquist, Gustaf
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Grundström, Helene
    Danderyds Hospital.
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC). Karolinska institutet.
    Effect of increasing workload on knee extensor and flexor muscular activity during cycling as measured with intramuscular electromyography.2018Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 13, nr 8, artikkel-id e0201014Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 9.
    da Silva, Julio Cézar Lima
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Tarassova, Olga
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Andersson, Eva
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Rönquist, Gustaf
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Quadriceps and hamstring muscle activity during cycling as measured with intramuscular electromyography.2016Inngår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 116, nr 9, s. 1807-1817Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 10.
    Eftestøl, Einar
    et al.
    University of Oslo, Norway.
    Psilander, Niklas
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet.
    Cumming, Kristoffer Toldnes
    Norwegian School of Sport Sciences, Norway..
    Juvkam, Inga
    University of Oslo, Norway.
    Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Sunding, Kerstin
    Karolinska Institutet.
    Wernbom, Mathias
    University of Gothenburg.
    Holmberg, Hans-Christer
    Mid Sweden University.
    Ekblom, Björn
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet, Björn Ekbloms forskningsgrupp.
    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?2019Inngår i: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601Artikkel i tidsskrift (Annet vitenskapelig)
  • 11.
    Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Är du chef? Överraska mig!: Krönika2015Inngår i: Fysioterapeuten, ISSN 0016-3384, E-ISSN 0807-9277, nr 4, s. 45-Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 12.
    Ekblom, Maria
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Blom, Victoria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Forskningsgruppen för idrottspsykologi.
    Ekblom, Örjan
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet.
    Kallings, Lena
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet.
    Nooijen, Carla F J
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    Fysisk aktivitet och hjärnhälsa2018Inngår i: Fysioterapi, ISSN 1653-5804, nr 5, s. 32-35Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
    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.

  • 13.
    Ekblom, Maria
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC). Karolinska Institutet.
    Bojsen-Möller, Emil
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet.
    Tarassova, Olga
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Ekblom, Örjan
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet.
    Day-to day variations in physical activity patterns affect corticospinal excitability on the following day2019Inngår i: Brain Stimulation March-April 2019, vol 12, issue 2, Elsevier, 2019, Vol. 12, nr 2, s. 468-, artikkel-id 437Konferansepaper (Annet vitenskapelig)
  • 14.
    Ekblom, Maria
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC). Karolinska institutet.
    Ekblom, Örjan
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet.
    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.2019Inngår i: International Journal of Environmental Research and Public Health, ISSN 1661-7827, E-ISSN 1660-4601, Vol. 16, nr 24, artikkel-id E5136Artikkel i tidsskrift (Fagfellevurdert)
    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).

  • 15.
    Ekblom, Maria M
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Gago, Paulo
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Post activation potentiation of the plantar flexors at different knee angles2013Konferansepaper (Fagfellevurdert)
  • 16.
    Ekblom, Maria M Nordlund
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Thorstensson, Alf
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Effects of prolonged vibration on H-reflexes, muscle activation, and dynamic strength.2011Inngår i: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 43, nr 10, s. 1933-9Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 17.
    Ekblom, Maria
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Ovendal, Alexander
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Tais, Senna
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Halvorsen, Kjartan
    KTH.
    Eriksson, Martin
    KTH.
    Acute effects of concurrent EMG feedback on knee extensor strength and activation2012Konferansepaper (Fagfellevurdert)
  • 18.
    Ekblom, Örjan
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Relations between motor proficiency and sub-components of physical activity in children2012Inngår i: Be active 2012 Abstracts: Supplement to Journal of Science and Medicine in Sport 15(6):77. Dec 2012, 2012, s. 77-Konferansepaper (Fagfellevurdert)
  • 19. Eriksson Crommert, Martin
    et al.
    Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Thorstensson, Alf
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Motor control of the trunk during a modified clean and jerk lift.2014Inngår i: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 24, nr 5, s. 758-763Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 20. Eriksson Crommert, Martin
    et al.
    Halvorsen, Kjartan
    Ekblom, Maria M
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Trunk Muscle Activation at the Initiation and Braking of Bilateral Shoulder Flexion Movements of Different Amplitudes.2015Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, nr 11, artikkel-id e0141777Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 21.
    Eriksson-Crommert, Martin
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Thorstensson, Alf
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Effects of arm movement amplitude on the initial trunk muscle activation pattern during raptid bilateral shoulder flexions during standing2012Konferansepaper (Fagfellevurdert)
  • 22.
    Frank, Per
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet, Forskningsgruppen Mitokondriell funktion och metabolisk kontroll.
    Andersson, Eva
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet, Forskningsgruppen Mitokondriell funktion och metabolisk kontroll.
    Pontén, Marjan
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet.
    Ekblom, Björn
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet, Björn Ekbloms och Mats Börjessons forskningsgrupp.
    Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Sahlin, Kent
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet, Forskningsgruppen Mitokondriell funktion och metabolisk kontroll.
    Strength training improves muscle aerobic capacity and glucose tolerance in elderly2016Inngår i: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 26, nr 7, s. 764-773Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 23.
    Gago, Paulo
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC). Karolinska Institutet.
    Marques, Mário C.
    University of Beira Interior (UBI), Covilhã, Portugal.
    Marinho, Daniel A.
    University of Beira Interior (UBI), Covilhã, Portugal.
    Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Effects of post activation potentiation on electromechanical delay2019Inngår i: Clinical Biomechanics, ISSN 0268-0033, E-ISSN 1879-1271, Vol. 70, s. 115-122Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 24.
    Gago, Paulo
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Tarassova, Olga
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Ekblom, Maria M
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Post activation potentiation can be induced without impairing tendon stiffness.2014Inngår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 114, nr 11, s. 2299-2308Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 25.
    Gago, Paulo
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap. Research Center for Sport, Health and Human Development, (CIDESD), Portugal.
    Arndt, Toni
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC). Department of CLINTEC, Karolinska Institutet, Stockholm.
    Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap. Department of Neuroscience, Karolinska Institutet, Stockholm.
    Post Activation Potentiation of the Plantarflexors: Implications of Knee Angle Variations2017Inngår i: Journal of Human Kinetics, ISSN 1640-5544, E-ISSN 1899-7562, Vol. 57, s. 29-38Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 26.
    Gago, Paulo
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Arndt, Toni
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Tarassova, Olga
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Post activation potentiation electromechanical delay and achilles tendon stiffness in athletes2014Konferansepaper (Fagfellevurdert)
  • 27.
    Gago, Paulo
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Arndt, Toni
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Tarrassova, Olga
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Post activation potentiation and Achilles tendon stiffness in power athletes2013Konferansepaper (Fagfellevurdert)
  • 28.
    Gago, Paulo
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    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
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Passive muscle length changes affects twitch potentiation in power athletes2012Inngår i: 8th International Conference on Strength Training: Book of abstracts / [ed] Håvard Wiig et al, 2012, s. 212-213Konferansepaper (Fagfellevurdert)
  • 29.
    Gago, Paulo
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Marques, Mário C
    Marinho, Daniel A
    Ekblom, Maria M
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Passive Muscle Length Changes Affect Twitch Potentiation in Power Athletes.2014Inngår i: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 46, nr 7, s. 1334-1342Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 30.
    Gago, Paulo
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    Zoellner, Anja
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    Cezar, Julio
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Ekblom, Maria M
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Post Activation Potentiation and Concentric Contraction Performance: Effects on Rate of Torque Development, Neuromuscular Efficiency and Tensile Properties.2018Inngår i: Journal of Strength and Conditioning Research, ISSN 1064-8011, E-ISSN 1533-4287Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 31.
    Godhe, Manne
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet.
    Ekblom, Örjan
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet.
    Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC). Karolinska Institutet.
    Pontén, Marjan
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet.
    Andersson, Eva
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC). Karolinska Institutet.
    Improved daily movement patterns in an accelerometer-assessed 8-weeks exercise project in older adults2019Inngår i: British Journal of Sports Medicine Vol 53, suppl 1, BMJ Publishing Group Ltd, 2019, Vol. 53, s. A2-Konferansepaper (Annet vitenskapelig)
  • 32. Helgadóttir, Björg
    et al.
    Owen, Neville
    Dunstan, David W.
    Ekblom, Örjan
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet, Björn Ekbloms forskningsgrupp.
    Hallgren, Mats
    Forsell, Yvonne
    Changes in physical activity and sedentary behavior associated with an exercise intervention in depressed adults2017Inngår i: Psychology of Sport And Exercise, ISSN 1469-0292, E-ISSN 1878-5476, Vol. 30, s. 10-18Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background Exercise is beneficial for depression, but less is known about its impact on post-intervention physical activity and sedentary behavior. The aim of this paper was to determine the extent to which participation in light-, moderate- and vigorous-intensity exercise intervention influenced habitual physical activity and sedentary behavior patterns in depressed adults. Methods Accelerometer data was collected pre- and post-intervention from depressed participants randomized to one of three 12-week intervention groups: light (n = 21), moderate (n = 25) and vigorous (n = 22) exercise. Mixed models examined changes in time spent sedentary and in light and moderate-to-vigorous physical activity (MVPA); time accumulated in sedentary and MVPA bouts; and, number of MVPA bouts and interruptions in sedentary time. Results Overall sedentary time decreased while light activity time increased across all intervention groups but not significantly so. The light exercise intervention group reduced MVPA minutes (−8.22, 95% CI: −16.44, −0.01), time in MVPA bouts (−8.44, 95% CI: −14.27, −2.62), and number of activity bouts (−0.43, 95% CI: −0.77, −0.09). The moderate exercise intervention group reduced time in MVPA bouts (−6.27, 95% CI: −11.71, −0.82) and number of sedentary interruptions (−6.07, 95% CI: −9.30, −2.84). No changes were observed for the vigorous exercise intervention group. Conclusions The exercise intervention led to an increase in overall light physical activity and decrease in sedentary time, though neither change was statistically significant. Participation in the light and moderate exercise intervention groups was associated with reductions of time in MVPA bouts, but this was not evident for the vigorous exercise intervention group.

  • 33.
    Hendy, Ashlee M
    et al.
    Deakin University, Geelong, Victoria, Australia.
    Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Latella, Christopher
    Edith Cowan University, Joondalup, Western Australia, Australia.
    Teo, Wei-Peng
    Deakin University, Geelong, Victoria, Australia.
    Investigating the effects of muscle contraction and conditioning stimulus intensity on short-interval intracortical inhibition.2019Inngår i: European Journal of Neuroscience, ISSN 0953-816X, E-ISSN 1460-9568, Vol. 50, nr 7, s. 3133-3140Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A reduction in short-interval intracortical inhibition (SICI) has been shown to accompany acute or chronic resistance exercise; however, little is known about how SICI is modulated under different contraction intensities. Therefore, the purpose of this study was to assess the effect of muscle contraction and conditioning stimulus intensity on the modulation of SICI. Single- and paired-pulse transcranial magnetic stimulation was applied to the primary motor cortex (M1), and motor evoked potentials (MEPs) were recorded from the biceps brachii in 16 adults (10M/6F). A conditioning-test stimulus paradigm (3 ms inter-stimulus intervals) was delivered during 10%, 20%, 40% and 75% of maximal voluntary isometric contraction (MVIC). At each force level, conditioning stimulus intensities of 60%, 70% and 80% of active motor threshold (AMT) were tested. Single-pulse MEPs were expressed as a proportion of the maximal muscle compound action potential, while SICI was quantified as a ratio of the unconditioned MEP. MEP amplitude increased with force output, with the greatest increase at 75% of MVIC. A reduction in SICI was observed from 40% to 75% of MVIC, but not 10%-40% of MVIC. There was no significant interaction between conditioning stimulus intensity and force level. The conditioning stimulus intensity (60%, 70% or 80% of AMT) did not alter the modulation of SICI. SICI was reduced at 75% of MVIC compared with the lower force outputs, and the magnitude of SICI in individual participants at different force outputs was not related. The findings suggest that strong muscle contractions are accompanied by less inhibition, which may have implications for neuroplasticity in exercise interventions.

  • 34.
    Hirschberg, Angelica Lindén
    et al.
    Karolinska institutet, Stockholm, Sweden.
    Elings Knutsson, Jona
    Karolinska universitetssjukhuset, Stockholm, Sweden.
    Helge, Torbjörn
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet.
    Godhe, Manne
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet.
    Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Bermon, Stephane
    Monaco Institute of Sports Medicine, Monaco.
    Ekblom, Björn
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet, Björn Ekbloms forskningsgrupp.
    Effects of moderately increased testosterone concentration on physical performance in young women: a double blind, randomised, placebo controlled study2019Inngår i: British Journal of Sports Medicine, ISSN 0306-3674, E-ISSN 1473-0480Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Objective To investigate the effects of a moderate increase in serum testosterone on physical performance in young, physically active, healthy women.Methods A double blind, randomised, placebo controlled trial was conducted between May 2017 and June 2018 (ClinicalTrials.gov ID: NCT03210558). 48 healthy, physically active women aged 18–35 years were randomised to 10 weeks of treatment with 10 mg of testosterone cream daily or placebo (1:1). All participants completed the study. The primary outcome measure was aerobic performance measured by running time to exhaustion (TTE). Secondary outcomes were anaerobic performance (Wingate test) and muscle strength (squat jump (SJ), counter movement jump (CMJ) and knee extension peak torque). Hormone levels were analysed and body composition assessed by dual energy X-ray absorptiometry.Results Serum levels of testosterone increased from 0.9 (0.4) nmol/L to 4.3 (2.8) nmol/L in the testosterone supplemented group. TTE increased significantly by 21.17 s (8.5%) in the testosterone group compared with the placebo group (mean difference 15.5 s; P=0.045). Wingate average power, which increased by 15.2 W in the testosterone group compared with 3.2 W in the placebo group, was not significantly different between the groups (P=0.084). There were no significant changes in CMJ, SJ and knee extension. Mean change from baseline in total lean mass was 923 g for the testosterone group and 135 g for the placebo group (P=0.040). Mean change in lean mass in the lower limbs was 398 g and 91 g, respectively (P=0.041).Conclusion The study supports a causal effect of testosterone in the increase in aerobic running time as well as lean mass in young, physically active women.

  • 35.
    Larsson, Kristina
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap. Sophiahemmet University.
    Ekblom, Örjan
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet.
    Kallings, Lena
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet.
    Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC). Karolinska institutet.
    Blom, Victoria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Forskningsgruppen för idrottspsykologi. Karolinska institutet.
    Job Demand-Control-Support Model as Related to Objectively Measured Physical Activity and Sedentary Time in Working Women and Men.2019Inngår i: International Journal of Environmental Research and Public Health, ISSN 1661-7827, E-ISSN 1660-4601, Vol. 16, nr 18, artikkel-id E3370Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A physically active lifestyle incurs health benefits and physically active individuals show reduced reactivity to psychosocial stressors. However, the findings are inconclusive and are based on self-reported physical activity and sedentary time. The present study aimed at studying the associations between psychological stressors (job demand, control, support, JD-C-S) and objectively measured physical activity (PA) on various intensities from sedentary (SED) to vigorous physical activity. The participants were 314 employees from a cross-sectional study. PA data were collected with the accelerometer ActiGraph GT3X (Pensacola, FL, USA), SED data with the inclinometer activPAL (PAL Technologies Ltd., Glasgow, Scotland, UK), and psychosocial stressors with a web questionnaire. Results showed that vigorous-intensity PA was negatively associated with demand (β -0.15, p < 0.05), even when adjusted for the covariates. SED was negatively associated to support (β -0.13, p < 0.05). Stress significantly moderated relations between support and sedentary time (β -0.12, p < 0.05). Moderate PA (MVPA) was negatively associated with demand, but only when controlling for overtime (β -0.13, p < 0.05). MVPA was also negatively associated with control (β -0.15, p < 0.05) but not when work engagement was included in the model. Being more physically active and spending less time sedentary may help to handle job situations with high demand and low support.

  • 36.
    Larsson, Kristina
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    Ekblom, Örjan
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet.
    Kallings, Lena
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet.
    Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Blom, Victoria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Forskningsgruppen för idrottspsykologi.
    Job demands control model as related to objectively measured physical activity and sitting time in working women and men2019Konferansepaper (Annet vitenskapelig)
  • 37.
    Larsson, Kristina
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    Kallings, Lena
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet.
    Ekblom, Örjan
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet.
    Blom, Victoria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Forskningsgruppen för idrottspsykologi.
    Andersson, Eva
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Criterion validity and test-retest reliability of SED-GIH, a single item question for assessment of daily sitting time.2019Inngår i: BMC Public Health, ISSN 1471-2458, E-ISSN 1471-2458, Vol. 19, nr 1, artikkel-id 19:17Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    BACKGROUND: Sedentary behaviour has been closely linked to metabolic and cardiovascular health and is therefore of importance in disease prevention. A user-friendly tool for assessment of sitting time is thus needed. Previous studies concluded that the present tools used to assess a number of sedentary behaviours are more likely to overestimate sitting than single-item questions which often underestimate sitting time, and that categorical answering options are recommended. In line with this, the single-item question with categorical answering options, SED-GIH, was developed. The aim of this study was to investigate the criterion validity of the SED-GIH question using activPAL3 micro as the criterion measure. The second aim was to evaluate the test-retest reliability of the SED-GIH questionnaire.

    METHOD: In the validity section of this study, 284 middle-aged adults answered a web questionnaire, which included SED-GIH, wore activPAL and filled in a diary log for one week. Spearman's rho assessed the relationship between the SED-GIH answers and the daily average sitting time as monitored by the activPAL (activPAL-SIT), a Weighted Kappa assessed the agreement, ANOVA assessed differences in activPAL-SIT between the SED-GIH answer categories, and a Chi2 compared the proportions of hazardous sitters between the different SED-GIH answer categories. In the reliability section, 95 elderly participants answered the SED-GIH question twice, with a mean interval of 5.2 days. The reliability was assessed with ICC and a weighted Kappa.

    RESULTS: The SED-GIH question correlated moderately with activPAL-SIT (rho = 0.31), with a poor agreement (weighted Kappa 0.12). In total, 40.8% underestimated and 22.2% overestimated their sitting time. The ANOVA showed significant differences in activPAL-SIT between the different SED-GIH answer categories (p < 0.001). The Chi2 showed a significant difference in proportion of individuals sitting more than 10 h per day within each SED-GIH answer category. ICC for the test-retest reliability of SED-GIH was excellent with ICC = 0.86, and the weighted Kappa showed an agreement of 0.77.

    CONCLUSIONS: The unanchored single item SED-GIH question showed excellent reliability but poor validity in the investigated populations. Validity and reliability of SED-GIH is in line with other questionnaires that are commonly used when assessing sitting time.

  • 38. Löscher, Wolfgang N
    et al.
    Nordlund (Ekblom), Maria M
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Central fatigue and motor cortical excitability during repeated shortening and lengthening actions.2002Inngår i: Muscle and Nerve, ISSN 0148-639X, E-ISSN 1097-4598, Vol. 25, nr 6, s. 864-72Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A decline in voluntary muscle activation and adaptations in motor cortical excitability contribute to the progressive decline in voluntary force during sustained isometric contractions. However, the neuronal control of muscle activation differs between isometric and dynamic contractions. This study was designed to investigate voluntary activation, motor cortex excitability, and intracortical inhibition during fatiguing concentric and eccentric actions. Eight subjects performed 143 torque motor-controlled, repeated shortening and lengthening actions of the elbow flexor muscles. Transcranial magnetic stimulation (TMS) was applied three times every 20 cycles. Magnetic evoked motor potentials (MEP), duration of the silent period (SP), and the torque increase due to TMS were analyzed. TMS resulted in a small torque increase in unfatigued actions. With repeated actions, voluntary torque dropped rapidly and the amplitude of the TMS-induced twitches increased, especially during repeated lengthening actions. MEP area of biceps brachii and brachioradialis muscles increased during repeated actions to a similar extent during lengthening and shortening fatigue. The duration of biceps and brachioradialis SP did not change with fatigue. Thus, voluntary activation became suboptimal during fatiguing dynamic actions and motor cortex excitability increased without any changes in intracortical inhibition. The apparent dissociation of voluntary activation and motor cortex excitability suggests that the central fatigue observed, especially during lengthening actions, did not result from changes in motor cortex excitability.

  • 39.
    Meckbach, Jane
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Forskningsgruppen för pedagogik, idrott och fritidskultur.
    Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Från magisterkurs till masterexamen2014Inngår i: Från Kungl. Gymnastiska Centralinstitutet till Gymnastik- och idrottshögskolan: en betraktelse av de senaste 25 åren som del av en 200-årig historia / [ed] Suzanne Lundvall, Stockholm: Gymnastik- och idrottshögskolan, GIH , 2014, s. 127-132Kapittel i bok, del av antologi (Annet (populærvitenskap, debatt, mm))
  • 40.
    Nooijen, Carla F J
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    Blom, Victoria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Forskningsgruppen för idrottspsykologi.
    Ekblom, Örjan
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet.
    Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Kallings, Lena
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet.
    Improving office workers' mental health and cognition: a 3-arm cluster randomized controlled trial targeting physical activity and sedentary behavior in multi-component interventions2019Inngår i: BMC Public Health, ISSN 1471-2458, E-ISSN 1471-2458, Vol. 19, artikkel-id 266Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background

    Physically inactive and sedentary lifestyles are negatively related to both mental health and cognition. For office-workers, who spend two-thirds of their workday sitting, it is important to improve these lifestyles. The aim of this study is to assess the effectiveness of multi-component interventions, incorporating individual, environmental and organizational changes, to increase physical activity or reduce sedentary behavior among office-workers in order to improve mental health and cognition.

    Methods

    a 3-arm, clustered randomized controlled trial (RCT) with waiting list control group amongst adult office-workers of two large Swedish companies. Cluster teams will be randomized into 6-month interventions or to a passive waiting list control group which will receive the allocated intervention with a 6-month delay. Two multicomponent interventions will be studied of which one focuses on improving physical activity and the other on reducing sedentary behavior. Both interventions include 5 sessions of motivational counselling. In the physical activity intervention persons also get access to a gym and team leaders will organize lunch walks and encourage to exercise. In the sedentary behavior intervention standing- and walking meetings will be implemented and team leaders will encourage to reduce sitting. The recruitment target is 110 office-workers per arm (330 in total). Measurements will be repeated every 6months for a total intended duration of 24months. Proximal main outcomes are physical activity measured with accelerometers and sedentary behavior with inclinometers. Distal outcomes are self-reported mental health and a cognition test battery. Additional outcomes will include cardiovascular fitness, body composition, sleep, self-reported physical activity and sedentary behavior, other health habits, physical health, and working mechanisms from blood samples and questionnaires.

    Discussion

    This cluster RCT will contribute to the currently available evidence by comparing the effectiveness of multi-component interventions targeting physical activity or sedentary behavior with the end goal of improving mental health and cognition. This study is strong in its cluster randomized design, numerous objective outcome measures and long-term follow-up. The exact content of the interventions has been defined by combining theory with results from a larger research project as well as having a continuous dialogue with the involved companies.

  • 41.
    Nooijen, Carla F J
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap. Karolinska Institutet.
    Kallings, Lena
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet.
    Blom, Victoria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Forskningsgruppen för idrottspsykologi. Karolinska Institutet.
    Ekblom, Örjan
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet.
    Forsell, Yvonne
    Karolinska Institutet.
    Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC). Karolinska Institutet.
    Common Perceived Barriers and Facilitators for Reducing Sedentary Behaviour among Office Workers.2018Inngår i: International Journal of Environmental Research and Public Health, ISSN 1661-7827, E-ISSN 1660-4601, Vol. 15, nr 4, artikkel-id E792Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Qualitative studies identified barriers and facilitators associated with work-related sedentary behaviour. The objective of this study was to determine common perceived barriers and facilitators among office workers, assess subgroup differences, and describe sedentary behaviour. From two Swedish companies, 547 office workers (41 years (IQR = 35–48), 65% women, 66% highly educated) completed questionnaires on perceived barriers and facilitators, for which subgroup differences in age, gender, education, and workplace sedentary behaviour were assessed. Sedentary behaviour was measured using inclinometers (n = 311). The most frequently reported barrier was sitting is a habit (67%), which was reported more among women than men (X2 = 5.14, p = 0.03) and more among highly sedentary office workers (X2 = 9.26, p < 0.01). The two other most reported barriers were that standing is uncomfortable (29%) and standing is tiring (24%). Facilitators with the most support were the introduction of either standing- or walking-meetings (respectively 33% and 29%) and more possibilities or reminders for breaks (31%). The proportion spent sedentary was 64% at the workplace, 61% on working days, and 57% on non-working days. This study provides a detailed understanding of office workers’ ideas about sitting and means to reduce sitting. We advise to include the supported facilitators and individualized support in interventions to work towards more effective strategies to reduce sedentary behaviour.

  • 42.
    Nooijen, Carla F J
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    Kallings, Lena
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet.
    Blom, Victoria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Forskningsgruppen för idrottspsykologi.
    Ekblom, Örjan
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Åstrandlaboratoriet.
    Forsell, Yvonne
    Karolinska Institutet.
    Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Common perceived barriers and facilitators for reducing sedentary behaviour among office-workers2018Inngår i: Journal of Physical Activity & Health, Volume 15, Issue 10, Pages S94-S95 Supplement 1, Canadian Consortium on Human Security, 2018, Vol. 15, nr 10, s. S94-S95Konferansepaper (Annet vitenskapelig)
  • 43.
    Nooijen, Carla F J
    et al.
    Department of Public Health Sciences, Karolinska Institutet.
    Möller, Jette
    Department of Public Health Sciences, Karolinska Institutet.
    Forsell, Yvonne
    Department of Public Health Sciences, Karolinska Institutet.
    Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Galanti, Maria R
    Department of Public Health Sciences, Karolinska Institutet.
    Engström, Karin
    Department of Public Health Sciences, Karolinska Institutet.
    Do unfavourable alcohol, smoking, nutrition and physical activity predict sustained leisure time sedentary behaviour? A population-based cohort study.2017Inngår i: Preventive Medicine, ISSN 0091-7435, E-ISSN 1096-0260, Vol. 101, s. 23-27, artikkel-id S0091-7435(17)30182-2Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Comparing lifestyle of people remaining sedentary during longer periods of their life with those favourably changing their behaviour can provide cues to optimize interventions targeting sedentary behaviour. The objective of this study was to determine lifestyle predictors of sustained leisure time sedentary behaviour and assess whether these predictors were dependent on gender, age, socioeconomic position and occupational sedentary behaviour. Data from a large longitudinal population-based cohort of adults (aged 18-97years) in Stockholm responding to public health surveys in 2010 and 2014 were analysed (n=49,133). Leisure time sedentary behaviour was defined as >3h per day of leisure sitting time e.g. watching TV, reading or using tablet. Individuals classified as sedentary at baseline (n=9562) were subsequently categorized as remaining sedentary (n=6357) or reduced sedentary behaviour (n=3205) at follow-up. Lifestyle predictors were unfavourable alcohol consumption, smoking, nutrition, and physical activity. Odds ratios (OR) and corresponding 95% Confidence Intervals (CI) were calculated, adjusting for potential confounders. Unfavourable alcohol consumption (OR=1.22, CI:1.11-1.34), unfavourable candy- or cake consumption (OR=1.15, CI:1.05-1.25), and unfavourable physical activity in different contexts were found to predict sustained sedentary behaviour, with negligible differences according to gender, age, socioeconomic position and occupational sedentary behaviour. People with unfavourable lifestyle profiles regarding alcohol, sweets, or physical activity are more likely to remain sedentary compared to sedentary persons with healthier lifestyle. The impact of combining interventions to reduce leisure time sedentary behaviour with reducing alcohol drinking, sweet consumption and increasing physical activity should be tested as a promising strategy for behavioural modification.

  • 44.
    Nordlund Ekblom, Maria M
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Improvements in dynamic plantar flexor strength after resistance training are associated with increased voluntary activation and V: M ratio.2010Inngår i: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 109, nr 1, s. 19-26Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of this study was to investigate if, and via what mechanisms, resistance training of the plantar flexor muscles affects voluntary activation during maximal voluntary eccentric and concentric muscle actions. Twenty healthy subjects were randomized into a resistance training group (N = 9) or a passive control group (N = 11). Training consisted of 15 sessions of unilateral mainly eccentric plantar flexor exercise over a 5-week period. During pre- and post-training testing, dynamic plantar flexor strength was measured and voluntary activation was calculated using the twitch interpolation technique. The Soleus H-reflex was used to assess motoneurone excitability and presynaptic inhibition of Ia-afferents whereas the Soleus V-wave to test for both changes in presynaptic inhibition of Ia-afferents and changes in supraspinal inputs to the motoneurone pool. H-reflexes, V-waves, supramaximal M-waves and twitches were evoked as the foot was moved at 5 degrees (.)s(-1) through an angle of 90 degrees during passive ankle rotations (passive H and M) and during maximal voluntary concentric and eccentric plantar flexion (MVC H, M and V-wave). Training induced significant improvements in plantar flexor strength and voluntary activation during both concentric and eccentric maximal voluntary actions. Soleus passive and MVC H:M ratios remained unchanged after training, whereas the Soleus V:M ratio was increased during both concentric and eccentric contractions after training. No change was seen in the control group for any of the parameters. The enhanced voluntary strength could be attributed partly to an increase in voluntary activation induced by eccentric training. Since the passive and MVC H:M ratios remained unchanged, the increase in activation is probably not due to decreased presynaptic inhibition. The increased V:M ratio for both action types indicate, that increased voluntary drive from supraspinal centers and/or modulation in afferents other than Ia:s, may have contributed to such an increase in voluntary activation.

  • 45.
    Nordlund Ekblom, Maria M
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Eriksson, Martin
    STH, KTH.
    Concurrent EMG feedback acutely improves strength and muscle activation.2012Inngår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 112, nr 5, s. 1899-1905Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purpose of this study was to investigate the acute effects of electromyographic (EMG) feedback on muscle activation and strength during maximal voluntary concentric and eccentric muscle actions. 15 females performed two sets of three lengthening and three shortening maximal voluntary isokinetic knee extensions at 20° s(-1) over 60° range of motion. After the first set, subjects were randomized to either a control group (n = 8) or a feedback group (n = 7). In the second set, the control group performed tasks identical to those in the first set, whereas the feedback group additionally received concurrent visual feedback of the EMGrms from Vastus Medialis (VM). Knee extensor strength and EMG activation of VM, Vastus lateralis (VL) and hamstrings (HAM) were measured during the MVCs. Analyses were performed separately in a 1 s preactivation phase, a 1 s initial movement phase and a 1 s late movement phase. EMG feedback was associated with significantly higher knee extensor strength in all phases (20.5% p < 0.05, 18.2% p < 0.001 and 19% p < 0.001, respectively) for the eccentric MVCs and in the preactivation phase (16.3%, p < 0.001) and initial movement phases (7.2%, p < 0.05) for concentric MVCs. EMG feedback from VM further improved activation in VM and HAM but not VL. These findings suggested that concurrent visual EMG feedback from VM could acutely enhance muscle strength and activation. Before recommending implementation of EMG feedback in resistance training paradigms, the feedback parameters needs to be optimized and its long-term effects needs to be scrutinized.

  • 46.
    Nordlund Ekblom, Maria M
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Thorstensson, Alf
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Cresswell, Andrew G
    Central and peripheral contributions to fatigue in relation to level of activation during repeated maximal voluntary isometric plantar flexions.2004Inngår i: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 96, nr 1, s. 218-25Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study aimed to investigate central and peripheral contributions to fatigue during repeated maximal voluntary isometric plantar flexions (MVCs). Changes in joint torque, level of activation (LOA), resting twitch amplitude (RT), electromyographic signals (EMG), and presynaptic inhibition of Ia afferents were investigated during 9 bouts of 10 MVCs. MVCs lasted for 2 s and were separated by 1 s. The interval between bouts was 10 s. Electrical stimulation was applied to the tibial nerve; at rest to evoke RTs, M waves, and two (1.5-s interval) H reflexes; with the soleus EMG at 30% of that during MVC to evoke M waves and two H reflexes; and during MVCs to measure LOA. Over the nine bouts, LOA decreased by 12.6% and RT by 16.2%. EMG root mean square during MVCs remained unchanged for the soleus and tibialis anterior muscles, but it decreased for medial gastrocnemius. Peripheral fatigue (decrease in RT) was positively correlated to LOA, whereas central fatigue (decrease in LOA) was not. Depression of both H reflexes suggests that presynaptic inhibition after the first bout was partly induced by homosynaptic postactivation depression of the Ia terminal. The H-reflex-to-M-wave ratio increased with fatigue in both passive and active states, with no change in the ratio of the second H reflex to the first, thereby indicating a decrease of presynaptic inhibition during fatigue. The results indicate that both central and peripheral mechanisms contributed to the fatigue observed during repeated MVCs and that the development of peripheral fatigue was influenced by the level of voluntary activation and initial plantar flexor torque.

  • 47.
    Nordlund Ekblom, Maria M
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Thorstensson, Alf
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Cresswell, Andrew G
    Conditioning Ia-afferent stimulation reduces the soleus Hoffman reflex in humans when muscle spindles are assumed to be inactive.2004Inngår i: Neuroscience Letters, ISSN 0304-3940, E-ISSN 1872-7972, Vol. 366, nr 3, s. 250-3Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Despite higher neural activation during active as compared to passive muscle shortening, Hoffman reflexes (H-reflexes) are similar. This may be explained by homosynaptic post-activation depression (HPAD) of Ia-afferents being present during active shortening. Accordingly, it was investigated whether conditioning electrical stimulation of the tibial nerve reduced the H-reflex less during active than passive shortening. The effects of two conditioning modes (0.2 and 1 Hz) were compared to a control mode without conditioning. H-reflexes and M-waves were elicited as the ankle passed 90 degrees with the soleus muscle undergoing passive or active (20% MVC) lengthening or shortening. Conditioning had no effect during active shortening. In contrast, during passive shortening, the H:M of the 1 Hz mode was significantly less than that of the 0.2 Hz and control modes. In lengthening, H:M was unaffected by conditioning. These findings support that HPAD reduces the synaptic efficacy of Ia-afferents during active shortening, active and passive lengthening, but not passive shortening.

  • 48.
    Nordlund Ekblom, Maria M
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Thorstensson, Alf
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Cresswell, Andrew G
    Variations in the soleus H-reflex as a function of activation during controlled lengthening and shortening actions.2002Inngår i: Brain Research, ISSN 0006-8993, E-ISSN 1872-6240, Vol. 952, nr 2, s. 301-7Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of soleus activation on the soleus H-reflex was investigated during controlled lengthening and shortening of the plantar flexor muscles. Maximal H-reflexes and M-waves were evoked at the same muscle length (ankle angle 90 degrees ) during lengthening and shortening (ankle angular velocity 5 degrees s(-1)) with soleus either passive or with its electromyographic activity at 10, 20 and 30% of that during a maximal voluntary isometric plantar flexion. In passive trials, the H(MAX):M(MAX) ratio during lengthening was lower than during shortening. In active trials at 10 and 20%, the H(MAX):M(MAX) ratio tended to be lower during lengthening than shortening. Within the active trials, H(MAX):M(MAX) ratios were not different between the three levels of soleus activation, neither for lengthening nor shortening actions. When all active trials were pooled, the lengthening H(MAX):M(MAX) ratio was significantly lower than the shortening one. In lengthening, the H(MAX):M(MAX) ratio increased in the active with respect to the passive condition, whereas no change occurred in active with respect to the passive shortening. These results indicate action type specificity in the way the Ia-excitatory effect is modulated as the soleus muscle is voluntarily activated.

  • 49.
    Nordlund Ekblom, Maria
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Thorstensson, Alf
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Strength training effects of whole-body vibration?2007Inngår i: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 17, nr 1, s. 12-7Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Whole-body vibration (WBV) has been suggested to have a beneficial effect on muscle strength. Manufacturers of vibration platforms promote WBV as an effective alternative or complement to resistance training. This study aimed to review systematically the current (August 2005) scientific support for effects of WBV on muscle strength and jump performance. MEDLINE and SPORT DISCUS were searched for the word vibration in combination with strength or training. Twelve articles were included in the final analysis. In four of the five studies that used an adequate design with a control group performing the same exercises as the WBV group, no difference in performance improvement was found between groups, suggesting no or only minor additional effects of WBV as such. Proposed neural mechanisms are discussed.

  • 50.
    Nordlund, Maria M.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    On spinal mechanisms for reflex control in man: modulation of Ia-afferent excitation with changes in muscle length, activation level and fatigue2004Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    To control muscle force, neural activation has to take alterations in muscle mechanics into account. This thesis assesses modulations in excitatory efficacy of Ia-afferents during muscle length changes at different levels of voluntary activation and during fatigue. Excitatory efficacy of Iaafferents was inferred from modulations in the Hoffmann reflex (Hreflex) elicited in the triceps surae. The H-reflex is affected by the excitability of the motoneurones, as well as presynaptic inhibition of Iaafferents. The latter can be induced by primary afferent depolarization (PAD) and homosynaptic post activation depression (HPAD) within the terminal. The H-reflex was depressed with increasing velocities of passive plantar flexor lengthening and was smaller during passive muscle lengthening than when the muscles were isometric or undergoing passive shortening. The depression was probably induced by a peripheral mechanism since it was present at a latency too short for supra-spinal involvement. The rapid modulation and the velocity dependency suggest that during muscle lengthening, muscle spindle firing may have induced HPAD in the Ia-terminal. The H-reflex increased from passive to active lengthening, whereas it remained unchanged from passive to active shortening. Despite similar neural activation during the active tasks, the H-reflex was lower during muscle lengthening than shortening, indicating more presynaptic inhibition during lengthening. When Iaafferents were conditioned by electrical stimulation to emulate muscle spindle activation, the H-reflex was depressed only during passive shortening. No depression of the H-reflex during active shortening implies that HPAD was already present in the active condition. The lack of increase in the H-reflex from passive to active shortening may thus be caused by muscle spindle activation reducing the efficacy of Ia-excitation in the active muscle via HPAD. During fatigue from maximal voluntary intermittent isometric plantar flexor actions, both central and peripheral fatigue developed. The stronger the subjects and the higher their ability to fully activate the plantar flexors, the greater was the amount of peripheral fatigue. After the first bout, presynaptic inhibition had increased, most likely due to HPAD. During the fatigue protocol, the amount of presynaptic inhibition decreased slightly, either due to decreased PAD-mediated inhibition or due to less HPAD as a result of reduced muscle spindle firing. Having two separate mechanisms, independently capable of modulating the efficacy of Iaafferents, provides the central nervous system with a high flexibility for regulating motoneurone excitability.

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