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  • 251. Schiffer, Tomas A
    et al.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's and Mats Börjesson's research group.
    Lundberg, Jon O
    Weitzberg, Eddie
    Larsen, Filip J
    Dynamic regulation of metabolic efficiency explains tolerance to acute hypoxia in humans.2014In: The FASEB Journal, ISSN 0892-6638, E-ISSN 1530-6860, Vol. 28, no 10, p. 4303-11Article in journal (Refereed)
    Abstract [en]

    The maximum power principle dictates that open biological systems tend to self-organize to a level of efficiency that allows maximal power production. Applying this principle to cellular energetics and whole-body physiology would suggest that for every metabolic challenge, an optimal efficiency exists that maximizes power production. On exposure to hypoxia, it would be favorable if metabolic efficiency would rapidly adjust so as to better preserve work performance. We tested this idea in humans by measuring metabolic efficiency and exercise tolerance under normoxic (Fio2=20.9%) and hypoxic (Fio2=16%) conditions, where Fio2 is fraction of inhaled oxygen. The results were compared with respirometric analyses of skeletal muscle mitochondria from the same individuals. We found that among healthy trained subjects (n=14) with a wide range of metabolic efficiency (ME), those with a high ME during normoxic exercise were able to better maintain exercise capacity (Wmax) in hypoxia. On hypoxic exposure, these subjects acutely decreased their efficiency from 19.2 to 17.4%, thereby likely shifting it closer to a degree of efficiency where maximal power production is achieved. In addition, mitochondria from these subjects had a lower intrinsic respiration compared to subjects that showed a large drop in Wmax in hypoxia An acute shift in efficiency was also demonstrated in isolated mitochondria exposed to physiological levels of hypoxia as P/O ratio increased from 0.9 to 1.3 with hypoxic exposure. These findings suggest the existence of a physiological adaptive response by which metabolic efficiency is dynamically optimized to maximize power production.-Schiffer, T. A., Ekblom, B., Lundberg, J. O., Weitzberg, E., Larsen, F. J. Dynamic regulation of metabolic efficiency explains tolerance to acute hypoxia in humans.

  • 252. Schiffer, Tomas A
    et al.
    Peleli, Maria
    Sundqvist, Michaela L
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's research group.
    Lundberg, Jon O
    Weitzberg, Eddie
    Larsen, Filip J
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Research group for Mitokondriell funktion och metabolisk kontroll.
    Control of Human Energy Expenditure by Cytochrome C Oxidase Subunit IV-2.2016In: American Journal of Physiology - Cell Physiology, ISSN 0363-6143, E-ISSN 1522-1563, Vol. 311, no 3, p. C452-C461Article in journal (Refereed)
    Abstract [en]

    Resting metabolic rate (RMR) in human shows pronounced individual variations, but the underlying molecular mechanism remains elusive. Cytochrome C oxidase (COX) plays a key role in control of metabolic rate and recent studies of the subunit 4 isoform 2 (COX IV-2) indicate involvement in the cellular response to hypoxia and oxidative stress. We evaluated whether the COX subunit IV isoform composition may explain the pronounced individual variations in resting metabolic rate (RMR). RMR was determined in healthy humans by indirect calorimetry and correlated to levels of COX IV-2 and COX IV-1 in Vastus Lateralis. Over expression and knock down of the COX IV isoforms were performed in primary myotubes followed by evaluation of the cell respiration and production of reactive oxygen species. Here we show that COX IV-2 protein is constitutively expressed in human skeletal muscle and strongly correlated to RMR. Primary human myotubes overexpressing COX IV-2 displayed markedly (>60%) lower respiration, reduced (>50%) cellular H2O2 production, higher resistance towards both oxidative stress and severe hypoxia compared to control cells. These results suggest an important role of isoform COX IV-2 in the control of energy expenditure, hypoxic tolerance and mitochondrial ROS homeostasis in humans.

  • 253. Schmied, C
    et al.
    Börjesson, Mats
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's and Mats Börjesson's research group.
    Sudden cardiac death in athletes.2014In: Journal of Internal Medicine, ISSN 0954-6820, E-ISSN 1365-2796, Vol. 275, no 2, p. 93-103Article in journal (Refereed)
    Abstract [en]

    A 'paradox of sport' is that in addition to the undisputed health benefits of physical activity, vigorous exertion may transiently increase the risk of acute cardiac events. In general, the risk of sudden cardiac death (SCD) approximately doubles during physical activity and is 2- to 3-fold higher in athletes compared to nonathletes. The incidence of SCD in young athletes is in fact very low, at around 1-3 per 100 000, but attracts much public attention. Variations in incidence figures may be explained by the methodology used for data collection and more importantly by differences between subpopulations of athletes. The incidence of SCD in older (≥35 years) athletes is higher and may be expected to rise, as more and older individuals take part in organized sports. SCD is often the first clinical manifestation of a potentially fatal underlying cardiovascular disorder and usually occurs in previously asymptomatic athletes. In the young (<35 years), SCD is mainly due to congenital/inherited cardiac abnormalities, whilst coronary artery disease (CAD) is the most common cause in older athletes. Cardiac screening including family/personal history, physical examination and resting electrocardiogram (ECG) may identify individuals at risk and has the potential to decrease the risk of SCD in young athletes. Screening including the ECG has a high sensitivity for underlying disease in young athletes, but the specificity needs to be improved, whereas the sensitivity of screening without the use of ECG is very low. The screening modality recommended for young athletes is of limited value in older athletes, who should receive individualized screening with cardiac stress testing for patients with high risk of underlying CAD. As cardiovascular screening will never be able to identify all athletes at risk, adequate preparedness is vital in case of a potentially fatal event at the sporting arena/facility. Firstly, we will review the magnitude of the problem of SCD in athletes of different ages, as well as the aetiology. Secondly, we will focus on how to prevent SCD in athletes of all ages, reviewing cardiovascular screening recommendations as well as emergency preparedness and arena safety.

  • 254.
    Seger, Jan
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    Westing, Stephen
    Hanson, Mats
    Karlson, Eddy
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    A new dynamometer measuring concentric and eccentric muscle strength in accelerated, decelerated, or isokinetic movements1988In: European Journal of Applied Physiology and Occupational Physiology, ISSN 0301-5548, E-ISSN 1432-1025, Vol. 57, p. 526-530Article in journal (Refereed)
    Abstract [en]

    A new computerized dynamometer (the SPARK System) is described. The system can measure concentric and eccentric muscle strength (torque) during linear or nonlinear acceleration or deceleration, isokinetic movements up to 400 degrees.s-1, and isometric torque. Studies were performed to assess: I. validity and reproducibility of torque measurements; II. control of lever arm position; III. control of different velocity patterns; IV. control of velocity during subject testing; and, V. intra-individual reproducibility. No significant difference was found between torque values computed by the system and known torque values (p greater than 0.05). No difference was present between programmed and external measurement of the lever arm position. Accelerating, decelerating and isokinetic velocity patterns were highly reproducible, with differences in elapsed time among 10 trials being never greater than 0.001 s. Velocity during concentric and eccentric isokinetic quadriceps contractions at 30 degrees.s-1, 120 degrees.s-1 and 270 degrees.s-1 never varied by more than 3 degrees.s-1 among subjects (N = 21). Over three days of testing, the overall error for concentric and eccentric quadriceps contraction peak torque values for 5 angular velocities between 30 degrees.s-1 and 270 degrees.s-1 ranged from 5.8% to 9.0% and 5.8% to 9.6% respectively (N = 25). The results indicate that the SPARK System provides valid and reproducible torque measurements and strict control of velocity. In addition, the intra-individual error is in accordance with those reported for other similar devices.

  • 255. Sjögren, Per
    et al.
    Fisher, Rachel
    Kallings, Lena
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's and Mats Börjesson's research group.
    Svenson, Ulrika
    Roos, Göran
    Hellénius, Mai-Lis
    Stand up for health-avoiding sedentary behaviour might lengthen your telomeres: secondary outcomes from a physical activity RCT in older people.2014In: British Journal of Sports Medicine, ISSN 0306-3674, E-ISSN 1473-0480, Vol. 48, no 19, p. 1407-9Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Telomere length has been associated with a healthy lifestyle and longevity. However, the effect of increased physical activity on telomere length is still unknown. Therefore, the aim was to study the relationship between changes in physical activity level and sedentary behaviour and changes in telomere length.

    METHODS: Telomere length was measured in blood cells 6 months apart in 49, 68-year-old, sedentary, overweight individuals taking part in a randomised controlled physical activity intervention trial. The intervention group received individualised physical activity on prescription. Physical activity was measured with a 7-day diary, questionnaires and a pedometer. Sitting time was measured with the short version of The International Physical Activity Questionnaire.

    RESULTS: Time spent exercising as well as steps per day increased significantly in the intervention group. Reported sitting time decreased in both groups. No significant associations between changes in steps per day and changes in telomere length were noted. In the intervention group, there was a negative correlation between changes in time spent exercising and changes in telomere length (rho=-0.39, p=0.07). On the other hand, in the intervention group, telomere lengthening was significantly associated with reduced sitting time (rho=-0.68, p=0.02).

    CONCLUSIONS: Reduced sitting time was associated with telomere lengthening in blood cells in sedentary, overweight 68-year-old individuals participating in a 6-month physical activity intervention trial.

  • 256. Solberg, E E
    et al.
    Börjesson, Mats
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's and Mats Börjesson's research group.
    Sharma, S
    Papadakis, M
    Wilhelm, M
    Drezner, J A
    Harmon, K G
    Alonso, J M
    Heidbuchel, H
    Dugmore, D
    Panhuyzen-Goedkoop, N M
    Mellwig, K-P
    Carre, F
    Rasmusen, H
    Niebauer, J
    Behr, E R
    Thiene, G
    Sheppard, M N
    Basso, C
    Corrado, D
    Sudden cardiac arrest in sports - need for uniform registration: A Position Paper from the Sport Cardiology Section of the European Association for Cardiovascular Prevention and Rehabilitation.2016In: European Journal of Preventive Cardiology, ISSN 2047-4873, E-ISSN 2047-4881, Vol. 23, no 6, p. 657-667Article in journal (Refereed)
    Abstract [en]

    There are large variations in the incidence, registration methods and reported causes of sudden cardiac arrest/sudden cardiac death (SCA/SCD) in competitive and recreational athletes. A crucial question is to which degree these variations are genuine or partly due to methodological incongruities. This paper discusses the uncertainties about available data and provides comprehensive suggestions for standard definitions and a guide for uniform registration parameters of SCA/SCD. The parameters include a definition of what constitutes an 'athlete', incidence calculations, enrolment of cases, the importance of gender, ethnicity and age of the athlete, as well as the type and level of sporting activity. A precise instruction for autopsy practice in the case of a SCD of athletes is given, including the role of molecular samples and evaluation of possible doping. Rational decisions about cardiac preparticipation screening and cardiac safety at sport facilities requires increased data quality concerning incidence, aetiology and management of SCA/SCD in sports. Uniform standard registration of SCA/SCD in athletes and leisure sportsmen would be a first step towards this goal.

  • 257. Spurway, N C
    et al.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    Noakes, T D
    Wagner, P D
    What limits VO2max?: A symposium held at the BASES Conference, 6 September 20102012In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 30, no 6, p. 517-531Article in journal (Refereed)
    Abstract [en]

    Three modern views about the factors limiting oxygen uptake in healthy humans are set against the original (early 1920s) concept of A. V. Hill and colleagues. The majority view for most of the intervening time has been that cardiac output is the essential limiting function. Among recent research in support of this contention is that, in quadrupeds, pericardiectomy, which allows greater diastolic filling, elevates maximum oxygen uptake; however, the relevance to bipedal exercise can be questioned. In any case, algebraic analyses of model systems indicate that all identifiable stages on the oxygen transport pathway, from pulmonary diffusion to oxidative phosphorylation in skeletal muscle mitochondria, materially influence maximum uptake. Thus, if a high cardiac output is to be of benefit, all the other steps must function better too. Nevertheless, these two viewpoints concur that the limit to maximum oxygen uptake is somatic. In contrast, there are strong indications that at altitudes where oxygen availability is about half that at sea level, cerebral oxygenation is a limiting factor, and some recent experiments raise the possibility that it might be a substantial influence at sea level also. Clearly, consensus cannot yet be reached on the question posed in the title.

  • 258. Svedenhag, Jan
    et al.
    Seger, Jan
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    Running on land and in water: comparative exercise physiology1992In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 24, no 10, p. 1155-1160Article in journal (Refereed)
    Abstract [en]

    The effect of water immersion on cardiorespiratory and blood lactate responses during running was investigated. Wearing a buoyant vest, 10 trained runners (mean age 26 yr) ran in water at four different and specified submaximal loads (target heart rates 115, 130, 145, and 155-160 beats.min-1) and at maximal exercise intensity. Oxygen uptakes (VO2), heart rates, perceived exertion, and blood lactate concentrations were measured. Values were compared with levels obtained during treadmill running. For a given VO2, heart rate was 8-11 beats.min-1 lower during water running than during treadmill running, irrespective of exercise intensity. Both the maximal oxygen uptake (4.03 vs 4.60 1 x min-1) and heart rate (172 vs 188 beats.min-1) were lower during water running. Perceived exertion (legs and breathing) and the respiratory exchange ratio (RER) were higher during submaximal water running than during treadmill running, while ventilation (1 x min-1) was similar. The blood lactate concentrations were consistently higher in water than on the treadmill, both when related to VO2 and to %VO2max. Partly in conformity with earlier cycle ergometer studies, these data suggest that immersion induces acute cardiac adjustments that extend up to the maximal exercise level. Furthermore, both the external hydrostatic load and an altered running technique may add to an increased anaerobic metabolism during supported water running.

  • 259.
    Svedenkrans, J.
    et al.
    Karolinska Inst, Dept Clin Sci Intervent & Technol, Stockholm, Sweden..
    Norman, M.
    Karolinska Inst, Dept Clin Sci Intervent & Technol, Stockholm, Sweden..
    Ekblom, Örjan
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's research group.
    Bohlin, K.
    Karolinska Inst, Dept Clin Sci Intervent & Technol, Stockholm, Sweden..
    THE EXPRESS/CHARM STUDY: 6.5 YEAR OLD CHILDREN BORN EXTREMELY PRETERM ARE LESS PHYSICALLY ACTIVE THAN TERM PEERS2016In: European Journal of Pediatrics, ISSN 0340-6199, E-ISSN 1432-1076, Vol. 175, no 11, p. 1821-1821Article in journal (Refereed)
  • 260. Svensson, M
    et al.
    Malm, C
    Tonkonogi, Michail
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    Sjödin, B
    Sahlin, Kent
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Research group for Mitokondriell funktion och metabolisk kontroll.
    Effect of Q10 supplementation on tissue Q10 levels and adenine nucleotide catabolism during high-intensity exercise.1999In: International Journal of Sport Nutrition, ISSN 1050-1606, Vol. 9, no 2, p. 166-80Article in journal (Refereed)
    Abstract [en]

    The aim of the present study was to investigate the concentration of ubiquinone-10 (Q10), at rest, in human skeletal muscle and blood plasma before and after a period of high-intensity training with or without Q10 supplementation. Another aim was to explore whether adenine nucleotide catabolism, lipid peroxidation, and mitochondrial function were affected by Q10 treatment. Seventeen young healthy men were assigned to either a control (placebo) or Q10-supplementation (120 mg/day) group. Q10 supplementation resulted in a significantly higher plasma Q10/total cholesterol level on Days 11 and 20 compared with Day 1. There was no significant change in the concentration of Q10 in skeletal muscle or in isolated skeletal muscle mitochondria in either group. Plasma hypoxanthine and uric acid concentrations increased markedly after each exercise test session in both groups. After the training period, the postexercise increase in plasma hypoxanthine was markedly reduced in both groups, but the response was partially reversed after the recovery period. It was concluded that Q10 supplementation increases the concentration of Q10 in plasma but not in skeletal muscle.

  • 261. Svensson, Michael B
    et al.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    Cotgreave, Ian A
    Norman, Barbara
    Sjöberg, Berit
    Ekblom, Örjan
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    Sjödin, Bertil
    Sjödin, Anders
    Adaptive stress response of glutathione and uric acid metabolism in man following controlled exercise and diet.2002In: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 176, no 1, p. 43-56Article in journal (Refereed)
    Abstract [en]

    Ergometer cycling performance as well as acute exercise-induced changes in the metabolism of energy-intermediates and glutathione (GSH) were investigated in skeletal muscle (SM) of 15 healthy young male subjects (VO(2max) approximately 54.7 mL kg(-1) min(-1), age approximately 25 years), before and after 3 days of controlled 'ìoverload-training' in combination with either high (62% of energy intake) or low (26% of energy intake) dietary intake of carbohydrates. The intake of a carbohydrate-rich diet clearly reduced the depletion of SM glycogen following the short-term training period, paralleled with a positive effect on the endurance performance, but not on high-intensity work-performance. An 'delayed over-reaching effect', defined as impaired work-performance, was observed after 2.5 days of recovery from the short-term training period, irrespective of the carbohydrate content of the diet and basal glycogen level in SM. Taken together, the main and novel findings of present investigation are: (1) an acute decrease of reduced GSH content and altered thiol-redox homeostasis in SM induced by strenuous high-intensity exercise; (2) an adaptive elevation of basal GSH level following the short-term training period; (3) an adaptive decrease of basal GSH level following 2.5 days recovery from training; (4) evidence of a relationship between the SM fibre type, physical performance capacity and GSH turnover during acute bouts of exercise; and (5) no evident effect of the level of carbohydrate intake on metabolism of GSH or energy intermediates. Furthermore, the induction of acute oxidative stress in exercising human SM and the adaptive responses to training are suggested to provide a protective antioxidant phenotype to the exercising SM during periods with repeated intense intermittent training.

  • 262. Taube, Jill
    et al.
    Ekblom Bak, Elin
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    Hellénius, Mai-Lis
    Karolinska institutet.
    Stillasittande och psykisk ohälsa2013In: Långvarigt stillasittande: en hälsofara i tiden / [ed] Elin Ekblom Bak, Studentlitteratur, 2013, p. 47-55Chapter in book (Other academic)
  • 263. Thulin, Petra
    et al.
    Nordahl, Gunnar
    Gry, Marcus
    Yimer, Getner
    Aklillu, Eleni
    Makonnen, Eyasu
    Aderaye, Getachew
    Lindquist, Lars
    Mattsson, C. Mikael
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's and Mats Börjesson's research group.
    Antoine, Daniel J.
    Park, B Kevin
    Linder, Stig
    Harrill, Alison H
    Watkins, Paul B.
    Glinghammar, Björn
    Schuppe-Koistinen, Ina
    Keratin-18 and microRNA-122 complement alanine aminotransferase as novel safety biomarkers for drug-induced liver injury in two human cohorts2014In: Liver international (Print), ISSN 1478-3223, E-ISSN 1478-3231, Vol. 34, no 3, p. 367-378Article in journal (Refereed)
    Abstract [en]

    BACKGROUND & AIMS:

    There is a demand for more sensitive, specific and predictive biomarkers for drug-induced liver injury (DILI) than the gold standard used today, alanine aminotransferase (ALT). The aim of this study was to qualify novel DILI biomarkers (keratin-18 markers M65/M30, microRNA-122, glutamate dehydrogenase and alpha-foetoprotein) in human DILI.

    METHODS:

    Levels of the novel biomarkers were measured by enzyme-linked immunosorbent assay or real-time quantitative reverse-transcription PCR (qRT-PCR) in two human DILI cohorts: a human volunteer study with acetaminophen and a human immunodeficiency virus (HIV)/tuberculosis (TB) study.

    RESULTS:

    In the acetaminophen study, serum M65 and microRNA-122 levels were significantly increased at an earlier time point than ALT. Furthermore, the maximal elevation of M65 and microRNA-122 exceeded the increase in ALT. In the HIV/TB study, all the analysed novel biomarkers increased after 1 week of treatment. In contrast to ALT, the novel biomarkers remained stable in a human cohort with exercise-induced muscular injury.

    CONCLUSIONS:

    M65 and microRNA-122 are potential biomarkers of DILI superior to ALT with respect to sensitivity and specificity.

  • 264.
    Unogård, Olof
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Forskningsgruppen för pedagogik, idrott och fritidskultur.
    Mattsson, C. Mikael
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    Idrottare spolar inte kröken2013In: Svensk Idrottsforskning: Organ för Centrum för Idrottsforskning, ISSN 1103-4629, Vol. 22, no 3, p. 17-21Article in journal (Other academic)
    Abstract [sv]

    Alkohol och idrott hör inte ihop sägs det. Men en genomgång av forskningen visar att det är ytterst tveksamt om idrotten hjälper till att hålla idrottaren borta från flaskan alla gånger.  Studierna visar även att motiven till varför man dricker är många och olika.

  • 265.
    Wallberg, Linnea
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    Mattsson, C. Mikael
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    Enqvist, Jonas K.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    Plasma IL-6 concentration during ultra-endurance exercise2011In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 111, no 6, p. 1081-1088Article in journal (Refereed)
    Abstract [en]

    Interleukin 6 (IL-6) response was studied during two ultra endurance events – one laboratory 24 h protocol (9 men) with exercise intensity set to 60 % of VO2max and one Adventure Race over 6 days (12 men/6 women) with a self-selected race pace, including rests, of about 38 % of VO2max. In the 24 h protocol IL-6 level was elevated from 0.76 ± 0.48 pg mL-1 at rest to 7.16 ± 2.70 pg mL-1 at 6 h, and increased further to 10.58 ± 1.04 pg mL-1 at 12 h, but remained thereafter unchanged at 24 h, (10.89±0.36 pg mL-1). All participants had nearly identical values at 12 and 24 h, supporting intensity as main determinant in the IL-6 response since exercise duration did not increase IL-6 level after 12 h. Possible confounding factors do not seem to influence the IL-6 concentration during the longer races (>12h), but might very well do so during shorter exercise bouts. In the 6-day race IL-6 increased from rest to 24 h, but thereafter there was no change in plasma IL-6 value until the end of the race (140 h). There was no elevation of TNF-α in any of the protocols, suggesting that the competitors were free from systemic inflammation. During endurance exercise lasting >12 h intensity and not duration is the main determinant of the IL-6 response, while during shorter exercise bouts both intensity and duration contribute to the accumulation of IL-6 in plasma.

  • 266. Westing, Stephen
    et al.
    Seger, Jan
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    Eccentric and Concentric Torque-Velocity Characteristics, Torque Output Comparisons, and Gravity Effect Torque Corrections for the Quadriceps and Hamstring Muscles in Females1989In: International Journal of Sports Medicine, ISSN 0172-4622, E-ISSN 1439-3964, Vol. 10, no 3, p. 175-180Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to assess and compare eccentric (ECC) and concentric (CONC) torque output of the quadriceps and hamstring muscles and to analyze the effect of gravity effect torque (GET) correction on the calculation of the hamstring/quadriceps peak torque quotient (H/Q quotient). Twenty female subjects performed maximal voluntary CONC and ECC contractions of the quadriceps and hamstring muscles at five isokinetic lever arm velocities from 60 degrees/s to 360 degrees/s. Peak torque was measured and corrected for GET. Mean ECC torque did not significantly change with increasing ECC velocity for either the quadriceps or hamstring muscles (P greater than 0.05). Mean CONC torques were significantly lower than the corresponding ECC torques (P less than 0.05) and decreased with increasing CONC velocity. At each test velocity, the CONC H/Q quotient was significantly lower than the corresponding ECC H/Q quotient (P less than 0.05). Mean H/Q quotients did not significantly change with increasing velocity for either the CONC or ECC tests (means: 0.46 and 0.57; P greater than 0.05). Mean H/Q quotients not corrected for GET significantly increased with increasing velocity for the CONC (0.61 to 0.78; P less than 0.05), but not ECC tests (0.66 to 0.71; P greater than 0.05). The results indicate that the ECC torque-velocity curve is essentially level for both quadriceps and hamstring muscles. The present findings point strongly toward the necessity of correcting for GET when calculating both CONC and ECC H/Q quotients.(ABSTRACT TRUNCATED AT 250 WORDS)

  • 267. Westing, Stephen
    et al.
    Seger, Jan
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences.
    Karlson, Eddy
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    Eccentric and concentric torque-velocity characteristics of the quadriceps femoris in man1988In: European Journal of Applied Physiology and Occupational Physiology, ISSN 0301-5548, E-ISSN 1432-1025, Vol. 58, p. 100-104Article in journal (Refereed)
    Abstract [en]

    The primary purpose of this investigation was to study the eccentric and concentric torque-velocity characteristics of the quadriceps femoris in man using a recently developed combined isometric, concentric and eccentric controlled velocity dynamometer (the SPARK System). A secondary purpose was to compare the method error associated with maximal voluntary concentric and eccentric torque output over a range of testing velocities. 21 males (21-32 years) performed on two separate days maximal voluntary isometric, concentric and eccentric contractions of the quadriceps femoris at 4 isokinetic lever arm velocities of 0 degree.s-1 (isometric), 30 degrees.s-1, 120 degrees.s-1 and 270 degrees.s-1. Eccentric peak torque and angle-specific torques (measured every 10 degrees from 30 degrees to 70 degrees) did not significantly change from 0 degrees.s-1 to 270 degrees.s-1 (p greater than 0.005) with the exception of angle-specific 40 degrees torque, which significantly increased; p less than 0.05). The mean method error was significantly higher for the eccentric tests (10.6% +/- 1.6%) than for the concentric tests (8.1% +/- 1.7%) (p less than 0.05). The mean method error decreased slightly with increasing concentric velocity (p greater than 0.05), and increased slightly with increasing eccentric velocity (p greater than 0.05). A tension restricting neural mechanism, if active during maximal eccentric contractions, could possibly account for the large difference seen between the present eccentric torque-velocity results and the classic results obtained from isolated animal muscle.

  • 268.
    Wichardt, Emma
    et al.
    Idrottsmedicin, Umeå universitet.
    Mattsson, C. Mikael
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    Henriksson-Larsén, Karin
    Swedish School of Sport and Health Sciences, GIH.
    Rhabdomyolysis/myoglobinemia and NSAID during 48-hours ultra-endurance exercise (adventure racing)2011In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 111, no 7, p. 1541-1544Article in journal (Refereed)
    Abstract [en]

    Purpose: To determine if rhabdomyolysis with myoglobinemia exists during a 48+ hour adventure race and if there is a correlation with NSAID use, race time and perceived pain or exertion. Method: Blood samples for analyses of myoglobin (Mb) were collected, and perception of exertion and pain registered on the Borg-RPE and CR scales, from 20 subjects (3 female, 17 male) Pre, Mid and Post race. Subjects were asked about NSAID use at each sampling and within 12 hours pre race. Result: A significant rise in Mb was observed throughout the race, with the NSAID group (n=6) having significantly lower Mb-Post than the no-NSAID group (n=14). High Mb-Pre and Post correlated to shorter race time and high Mb-Pre to lower Pain-Post. Race time also correlated to NSAID use, with the NSAID group having significantly longer race time than the no-NSAID group. Conclusion: Rhabdomyolysis with myoglobinemia, which might be reduced with NSAID use, exists during a 48+ hour adventure race. Indications that high Mb-levels correlate with shorter race time and less pain, and the reasons for the NSAID groups longer race time, need further investigation.

  • 269. Åstrand, Per-Olof
    et al.
    Ekblom, Örjan
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's and Mats Börjesson's research group.
    Ekblom, Bjorn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's and Mats Börjesson's research group.
    Född Till rörelse: En bok om kost och motion2011Book (Other (popular science, discussion, etc.))
    Abstract [sv]

    Praktiskt taget alla vuxna svenskar anser att regelbunden motion är bra för hälsa och arbetsförmåga. Vi är också upplysta om hur våra matvanor, alkoholintag och rökning påverkar vår hälsa. Varför är det då en minoritet som har en livsstil som styrs av kunskap och förnuft? Finns svaret förankrat i vårt biologiska arv? Hur levde våra förfäder? Att sitta still i flera timmar utan att röra sig alls utgör en risk för utveckling av hjärt- och kärlsjukdom, cancer och annan ohälsa, trots att man kanske motionerar ett par gånger i veckan. Den fysiologiska förklaringen är den att om inte musklerna får arbeta regelbundet, om än mycket lite, så påverkas viktiga processer i musklerna, som sedan påverkar hela kroppen. Det räcker att regelbundet resa sig och gå en liten bit för att undvika de negativa effekterna av långvarigt sittande.I Född till rörelse kan du läsa om faktorer som har betydelse för vår kondition och hälsa. Varför är det så viktigt att vi rör på oss? Hur kan man motverka eller mildra effekten av vissa sjukdomar? Vad innebär det att vara fysiskt aktiv? Hur ska man träna och hur jobbigt bör det vara?

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