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  • 101.
    Schagatay, Erika
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    van Kampen, Marja
    Emanuelsson, Stefan
    Holm, Boris
    Effects of physical and apnea training on apneic time and diving response in humans.2000In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 82, no 3, p. 161-169Article in journal (Refereed)
    Abstract [en]

    The aim of this investigation was to study separately the effects of physical training and apnea training on the diving response and apneic time in humans. Both types of training have been suggested to lead to prolonged apneic time and an increased “diving response” (i.e., regional vasoconstriction and bradycardia). The study was also designed to examine the effects of these two types of training on the characteristics of the increase in apneic time with repeated apneas. Simulated diving tests were performed before and after the different training programs. The test format was one apnea and five apneas with facial immersion in cold water at 2-min intervals. An increase in apneic time was observed after physical training (n=24), and this was attributable to an increased time beyond the physiological breaking point. The other parameters that were measured remained unaffected. After apnea training (n=9), however, apneic time was increased by a delay in the physiological breaking point, which is mainly determined by the arterial tension of CO2. The diving response had increased, and the effect of repeated apneas on apneic time tended to be larger after apnea training. These results may explain the pronounced diving responses and long apneas observed in trained apneic divers

  • 102.
    Schantz, Peter
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Om Lindhardskolan och dess betydelse i ett svenskt perspektiv2009In: Forskning i bevægelse. Et nyt forskningsfelt i et 100-årigt perspektiv / [ed] Anne Lykke Poulsen, Else Trangbæk, Kurt Jørgensen & Nikolai Nordsborg, København: Museum Tusculanums Forlag, 2009, p. 137-167Chapter in book (Other academic)
  • 103.
    Schulte, Stefanie
    et al.
    Institute of Motor Control and Movement Technique, German Sport University Cologne, Cologne, Germany.
    Schiffer, Thorsten
    Institute of Motor Control and Movement Technique, German Sport University Cologne, Cologne, Germany.
    Sperlich, Billy
    Institute of Training Science and Sport Informatics, German Sport University Cologne, Germany.
    Kleinöder, Heinz
    Institute of Training Science and Sport Informatics, German Sport University Cologne, Cologne, Germany.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Serum Concentrations of S100B are not Affected by Cycling to Exhaustion With or Without Vibration2011In: Journal of Human Kinetics, ISSN 1640-5544, E-ISSN 1899-7562, Vol. 30, no 1, p. 67-78Article in journal (Refereed)
    Abstract [en]

    The calcium-binding protein S100B is produced primarily by astrocytes and exerts concentration-dependentparacrine and autocrine effects on neurons and glia. The numerous findings of a correlation between S100B andtraumatic brain injury (TBI) have resulted in the employment of this protein as a clinical biomarker for such injury.Our present aim was to determine whether cycling with (V) or without (NV) vibration alters serum concentrations ofS100B. Twelve healthy, male non-smokers (age: 25.3±1.6 yrs, body mass: 74.2±5.9 kg, body height: 181.0±3.7 cm,VO2peak: 56.9±5.1 ml·min-1·kg-1(means ± SD)) completed in random order two separate trials to exhaustion on avibrating bicycle (amplitude 4 mm and frequency 20 Hz) connected to an ergometer. The initial workload of 100 W waselevated by 50 W every 5 min and the mean maximal period of exercise was 25:27±1:30 min. The S100B in venousblood taken at rest, immediately after the test, and 30, 60 and 240 min post-exercise exhibited no significant differences(p>0.05), suggesting that cycling with and without vibration does not influence this parameter.

  • 104.
    Severinsen, Kaare
    et al.
    Aarhus Univ Hosp, Dept Neurol, Noerrebrogade 44, DK-8000 Aarhus C, Denmark.
    Dalgas, Ulrik
    Aarhus Univ, Sect Sport Sci, Dept Publ Hlth, DK-8000 Aarhus C, Denmark.
    Overgaard, Kristian
    Aarhus Univ, Sect Sport Sci, Dept Publ Hlth, DK-8000 Aarhus C, Denmark.
    Pedersen, Asger R.
    Aarhus Univ, Hammel Neurorehabil & Res Ctr, DK-8000 Aarhus C, Denmark.
    Örtenblad, Niels
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. Univ Southern Denmark, Dept Sports Sci & Clin Biomech, SDU Muscle Res Cluster, Odense, Denmark.
    Lund, Caroline
    VIA Univ Coll, Aarhus N, Denmark.
    Jakobsen, Johannes K.
    Rigshosp, Dept Neurol, Copenhagen, Denmark.
    Andersen, Henning
    Aarhus Univ Hosp, Dept Neurol, Noerrebrogade 44, DK-8000 Aarhus C, Denmark.
    Skeletal muscle fiber characteristics and oxidative capacity in hemiparetic stroke survivors2016In: Muscle and Nerve, ISSN 0148-639X, E-ISSN 1097-4598, Vol. 53, no 5, p. 748-754Article in journal (Refereed)
    Abstract [en]

    Introduction: Skeletal muscle is changed after stroke, but conflicting data exist concerning muscle morphology and oxidative enzyme capacity. Methods: In 36 chronic stroke patients bilateral rectus femoris muscle biopsies were analyzed, and fiber type proportions and cross-sectional areas were determined by ATPase histochemistry. Enzymatic concentrations of citrate synthase (CS) and 3-Hydroxyacyl-coenzymeA-dehydrogenase (HAD) were determined using freeze-dried muscle tissue. Findings were correlated with clinical outcomes. Results: In the paretic muscles the mean fiber area was smaller (P=0.0004), and a lower proportion of type 1 fibers (P=0.0016) and a higher proportion of type 2X fibers (P=0.0002) were observed. The paretic muscle had lower CS (P=0.013) and HAD concentrations (P=0.037). Mean fiber area correlated with muscle strength (r=0.43; P=0.041), and CS concentration correlated with aerobic capacity (r=0.47; P=0.01). Conclusions: In stroke survivors there is a phenotypic shift toward more fatigable muscle fibers with reduced oxidative enzymatic capacity that relates to clinical outcomes. Muscle Nerve53: 748-754, 2016

  • 105.
    Sjörs, A.
    et al.
    The Institute of Stress Medicine, Gothenburg, Sweden.
    Ljung, Thomas
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Jonsdottir, I. H.
    The Institute of Stress Medicine, Gothenburg, Sweden.
    Diurnal salivary cortisol in relation to perceived stress at home and at work in healthy men and women2014In: Biological Psychology, ISSN 0301-0511, E-ISSN 1873-6246, Vol. 99, no 1, p. 193-197Article in journal (Refereed)
    Abstract [en]

    This study investigated the association between diurnal salivary cortisol profile and perceived stress at work and at home. Healthy participants (N= 180, 52% women) collected saliva cortisol samples immediately after waking up, 15. min later, 30. min later, and at 9:00, 12:00, 15:00, 18:00 and 21:00. The area under the cortisol awakening curve with respect to ground (AUCgCAR) and increase (AUCiCAR), and diurnal slope between 9:00 and 21:00 were analyzed. Perceived stress at work and at home was measured with the Stress-Energy Questionnaire.Participants reporting stress at home had significantly lower AUCgCAR and a flatter diurnal slope. When performing separate analyses for men and women, this association was only significant among women. Perceived stress at work was not associated with any cortisol measure.This study highlights the importance of stress outside the workplace. The sex differences may indicate an increased vulnerability to non-work stress in women. © 2014 Elsevier B.V.

  • 106.
    Sperlich, Billy
    et al.
    Department of Sport Science, University of Wuppertal, Wuppertal, Germany.
    Achtzehn, S
    Institute of Training Science and Sport Informatics, German Sport University, Köln, Germany.
    Buhr, M
    Institute of Health Promotion and Clinical Movement Science, Köln, Germany.
    Zinner, C
    Institute of Training Science and Sport Informatics, German Sport University, Köln, Germany.
    Zelle, S
    Institute of Training Science and Sport Informatics, German Sport University, Köln, Germany.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Salivary Cortisol, Heart Rate and Blood Lactate Responses During Elite Downhill Mountain Bike Racing2012In: International Journal of Sports Physiology and Performance, ISSN 1555-0265, E-ISSN 1555-0273, Vol. 7, no 1, p. 47-52Article, review/survey (Refereed)
    Abstract [en]

    Purpose: This study aimed to quantify the intensity profile of elite downhill mountain bike races during competitions. Methods: Seventeen maledownhill racers (22 ± 5 y; 185.1 ± 5.3 cm; 68.0 ± 3.9 kg; VO 2peak: 59.4 ± 4.1 mL min kg -1) participated in the International German DownhillChampionships in 2010. The racers' peak oxygen uptake and heart rate (HR) at 2 and 4 mmol L -1 blood lactate (HR2 and HR 4), were assessed during an incremental laboratory step test (100 W, increase 40 W every 5 min). During the races, the HR was recorded and pre- and postrace bloodlactate concentrations as well as salivary cortisol levels were obtained. Results: During the race, the absolute time spent in the "easy" intensity zone was 23.3 ± 6.8 s, 24.2 ± 12.8 s (HR 2-HR 4) in the "moderate" zone, and 151.6 ± 18.3 s (>HR 4) in the "hard" zone. Eighty percent of the entire race was accomplished at intensities >90% HRpeak. Blood lactate concentrations postrace were higher than those obtained after the qualification heat (8.0 ± 2.5 mmol L -1 vs 6.7 ± 1.8 mmol L -1, P < .01). Salivary levels of cortisol before the competition and the qualification heat were twice as high as at resting state (P < .01). Conclusions: This study shows that mountain bike downhill races are conducted at high heart rates and levels of blood lactate as well as increased concentration of salivary cortisol as marker for psycho-physiological stress. © 2011 Human Kinetics, Inc.

  • 107.
    Sperlich, Billy
    et al.
    Institute of Training Science and Sport Informatics, German Sport University Köln, Köln, Germany.
    Haegele, Matthias
    Institute of Training Science and Sport Informatics, German Sport University Köln, Köln, Germany.
    Krueger, Malte
    Institute of Training Science and Sport Informatics, German Sport University Köln, Köln, Germany.
    Schiffer, Thorsten
    Outpatient Clinic for Sports Traumatology and Public Health Consultation, German Sport University Köln, Köln, Germany.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Mester, Joachim
    Institute of Training Science and Sport Informatics, German Sport University Köln, Köln, Germany.
    Cardio-respiratory and metabolic responses to different levels of compression during submaximal exercise2011In: Phlebology, ISSN 0268-3555, E-ISSN 1758-1125, Vol. 26, no 3, p. 102-106Article in journal (Refereed)
    Abstract [en]

    Objective: The effects of knee-high socks that applied different levels of compression (0, 10, 20, 30 and 40 mmHg) on various cardio-respiratory and metabolic parameters during submaximal running were analysed. Methods: Fifteen well-trained, male endurance athletes (age: 22.2 +/- 1.3 years; peak oxygen uptake: 57.2 +/- 4.0 mL/minute/kg) performed a ramp test to determine peak oxygen uptake. Thereafter, all athletes carried out five periods of submaximal running (at approximately 70% of peak oxygen uptake) with and without compression socks that applied the different levels of pressure. Cardiac output and index, stroke volume, arteriovenous difference in oxygen saturation, oxygen uptake, arterial oxygen saturation, heart rate and blood lactate were monitored before and during all of these tests. Results: Cardiac output (P = 0.29) and index (P = 0.27), stroke volume (P = 0.50), arteriovenous difference in oxygen saturation (P = 0.11), oxygen uptake (P = 1.00), arterial oxygen saturation (P = 1.00), heart rate (P = 1.00) and arterial lactate concentration (P = 1.00) were unaffected by compression (effect sizes = 0.00-0.65). Conclusion: This first evaluation of the potential effects of increasing levels of compression on cardio-respiratory and metabolic parameters during submaximal exercise revealed no effects whatsoever.

  • 108.
    Sperlich, Billy
    et al.
    Institute of Training Science and Sport Informatics, German Sport University, Köln, Germany.
    Haegle, Mathias
    German Research Centre of Elite Sport, Am Sportpark Müngersdorf, 50933 Köln, Germany.
    Achtzehn, Silvia
    German Research Centre of Elite Sport, Am Sportpark Müngersdorf, 50933 Köln, Germany.
    Linville, John
    University of Nebraska at Omaha, Omaha, Nebraska, USA.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Mester, Joachim
    Institute of Training Science and Sport Informatics, German Sport University, Köln, Germany.
    Different types of compression clothing do not increase sub-maximal and maximal endurance performance in well-trained athletes2010In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 28, no 6, p. 609-614Article in journal (Refereed)
    Abstract [en]

    The effects of three textiles with increasing compressive surface were compared with non-compressive conventional clothing on physiological and perceptual variables during sub-maximal and maximal running. 15 well-trained endurance athletes (mean ± s, age: 27.1 ± 4.8 years, VO2max 63.7 ± 4.9 ml∙min-1∙kg-1) performed four sub-maximal (~70%VO2max) and maximal tests with and without different compression stockings, tights, and whole body compression suits. Arterial lactate concentration, oxygen saturation and partial pressure, pH, oxygen uptake and ratings of muscle soreness were recorded before, during, and after all tests. Additionally, time to exhaustion was assessed. Sub-maximal (P = 0.22) and maximal oxygen uptake (P = 0.26), arterial lactate concentration (P = 0.16; 0.20), pH (P = 0.23; 0.46), oxygen saturation (P = 0.13; 0.26) and oxygen partial pressure (P = 0.09; 0.20) did not differ between the types of clothing (effect sizes = 0.00-0.45). Ratings of perceived exertion (P = 0.10; 0.15), muscle soreness (P = 0.09; 0.10) and time to exhaustion (P = 0.16) were also unaffected by the different clothing (effect sizes = 0.28-0.85). For the first time, the effect on endurance performance of different types of compression clothing with increasing amount of compressive surface was evaluated. Overall, there were no performance benefits when using the compression garments.

  • 109.
    Sperlich, Billy
    et al.
    Institute of Training Science and Sport Informatics, German Sport University, Cologne, Germany.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Physiological effects of a new racing suit for elite cross country skiers2011In: Journal of Sports Medicine and Physical Fitness, ISSN 0022-4707, E-ISSN 1827-1928, Vol. 51, no 4, p. 555-559Article in journal (Refereed)
    Abstract [en]

    AIM: The aim of this paper was to investigate the influence of the new cross country racing suit, designed for the Olympic Winter Games in Vancouver 2010, on cardio-respiratory, thermoregulatory and perceptual responses.METHODS: Six elite cross country skiers (29±6 years, peak oxygen uptake 73.2±6.9 mL·min-1·kg-1) performed two exercise bouts wearing either the 2009 or the 2010 racing suit. Bouts consisted of incremental testing on roller skis (12 km·h-1 at 5° inclination; 11 km·h-1 at 6° inclination and 12 km·h-1at 8° inclination for six minutes).RESULTS: During increasing intensities, significantly lower values were found for oxygen uptake, minute ventilation, RER and heart rate when wearing the new suit compared to the old one (P<0.05; effect sizes: 0.21-4.00). Core temperature was lower with the new suit during steps 2 and 3 (P<0.05, effect size: 1.22-1.27). Also, mean skin temperature was lower during the last increment (P<0.05, effect size: 0.87).CONCLUSION:The new 2010 racing suit, developed specifically for the Olympic Winter Games in Vancouver 2010, demonstrated lower values for oxygen uptake, minute ventilation, heart rate, skin and core temperature, ratings of thermal and sweat sensation when compared to the 2009 racing suit.

  • 110.
    Sperlich, Billy
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. Department of Sport Science University of Würzburg, Würzburg, Germany.
    Osman-Reinkens, S
    Institute of Training Science and Sport Informatics, German Sport University, Cologne, Germany.
    Zinner, Christoph
    Institute of Training Science and Sport Informatics, German Sport University, Cologne, Germany.
    Krueger, M
    Institute of Training Science and Sport Informatics, German Sport University, Cologne, Germany.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Cardiorespiratory, metabolic and hormonal responses during open-wheel indoor kart racing2014In: Journal of Sports Medicine and Physical Fitness, ISSN 0022-4707, E-ISSN 1827-1928, Vol. 54, no 4, p. 475-480Article in journal (Refereed)
    Abstract [en]

    AIM: This study aimed to quantify the cardiorespiratory, metabolic and hormonal responses of elite open-wheel indoor kart racers.METHODS: Ten male racers (age: 21±3 yrs; height: 1.92±0.06 m, body mass: 76.0±5.9 kg) participated in a racing tournament. Their peak oxygen uptake and heart rate were assessed by a ramp test (100 W, increase 30 W·min-1) in the laboratory. During the racing itself, the cardio-respiratory and accelerometer values were recorded and pre- and post-race levels of blood lactate and salivary cortisol were determined.RESULTS: The average peak values for all of the drivers with respect to oxygen uptake and heart rate were 4.5±0.8 L·min-1 (56.7±7.9 mL·min-1·kg-1) and 193±5 beats·min-1, respectively. Overall, 28.3±3.3 laps were completed during 30-min of racing. Acceleration forces for the entire test averaged 1.20±0.51 G (maximum: 3.30 G), declining from the first 10 min until the end of racing (P<0.03). The oxygen uptake (~20 mL·min-1·kg-1), heart rate (~133 beats·min-1), respiratory exchange ratio (~0.96) and ventilation (~70 L·min-1) observed indicated moderate cardio-respiratory responses. Blood lactate concentration was significantly higher after the race than before but remained at <2 mmol·L-1 (P<0.01; effect size: 1.62).CONCLUSION: There were no differences between salivary cortisol levels before and after the race (P<0.06; effect size: 0.49). Directly after the race, the drivers rated their perceived exertion on Borg’s scale as 11.1±1.3. The present data revealed that the psycho-physical exertion associated with a 30-min open-wheel indoor kart race is moderate.

  • 111.
    Sperlich, Billy
    et al.
    Institute of Training Science and Sport Informatics, German Sport University, Köln, Germany.
    Schiffer, Thorsten
    Outpatient Clinic for Sports Traumatology and Public Health Consultation, Köln, Germany.
    Achtzehn, Silvia
    German Research Centre of Elite Sport, Am Sportpark Müngersdorf, 50933 Köln, Germany.
    Mester, Joachim
    Institute of Training Science and Sport Informatics, German Sport University, Köln, Germany.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Pre-exposure to hyperoxic air does not enhance power output during subsequent sprint cycling2010In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 110, no 2, p. 301-305Article in journal (Refereed)
    Abstract [en]

    Previous studies have indicated that aerobic pathways contribute to 13-27% of the energy consumed during short-term (10-20-second) sprinting exercise. Accordingly, the present investigation was designed to test the hypothesis that prior breathing of oxygen-enriched air (FinO2=60%) would enhance power output and reduce fatigue during subsequent sprint cycling. Ten well-trained male cyclists (mean ± SD, age: 25±3 years, height: 186.1±6.9 cm, body mass: 79.1±8.2 kg, maximal oxygen uptake [VO2max]: 63.2±5.2 ml·kg-1·min-1) took 25 breaths of either hyperoxic (HE) or normoxic (NO) air before performing 15 sec of cycling at maximal exertion. During this performance, the maximal and mean power outputs were recorded. The concentration of lactate, pH, partial pressure of and saturation by oxygen, [H+] and base excess in arterial blood were assessed before and after the sprint. The maximal (1053±141 W for HE versus 1052±165 W for NO; P = 0.77) and mean power outputs (873±123 versus 876±147 W; P = 0.68) did not differ between the two conditions. The partial pressure of oxygen was approximately 2.3-fold higher after inhaling HE in comparison to NO, while lactate concentration, pH, [H+] and base excess (best P = 0.32) after sprinting were not influenced by exposure to HE. These findings suggest that the peak and mean power outputs of athletes performing short-term intense exercise cannot be improved by pre-exposure to oxygen-enriched air.

  • 112.
    Sukhovey, Yurij G.
    et al.
    Institute of Clinical Immunology, Siberian Division of Russian Academy of Sciences, Tyumen, Russia.
    Koptyug, Andrey
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Quality Technology and Management, Mechanical Engineering and Mathematics. SportsTech Research Centre, Mid Sweden University.
    Fisher, Tatjana A.
    Tyumen Research Centre, Siberian Division of Russian Academy of Sciences, Tyumen, Russia.
    Petrov, Sergey A.
    Tyumen State Oil and Gas Institute, Volodarskogo st. 38, , 625000, Tyumen, .
    Dotsenko, Evgenij L.
    Tyumen State University, Semakova st. 10, 625003, Tyumen, Russia.
    Functional Conjugation of the Different Regulatory Responses to the Stress Stimuli in Healthy Human Subjects2016In: Open Journal of Applied Sciences, ISSN 2165-3917, Vol. 6, p. 489-500Article in journal (Refereed)
    Abstract [en]

    Present article discusses the physiological mechanisms of the state employees adaptation duringactive training in temporary groups. It is suggested that adaptive mechanisms to adverse effectsmay be studied basing on the concept of functional isomorphism of the psychic and immune systems.Adaptive mechanisms were studied through the monitoring of the stress factors’ impact upon thelaw enforcement officers when training outside the places of permanent deployment. The specificpurpose of present study was to evaluate the physiological indicators of the psychic, immune andendocrine systems dynamics at different stages of adaptation of the live organism to a stressfulsituation, hoping to get better insight into possible relations between psychic and immune domains.Through monitoring of the dynamics of the endocrine and immune responses to the psychic stimuli,it was possible to correlate the stages of the stress onset to the phases of specific immune reactions.Strong correlations between the parameters characterizing activation of the psychic and immuneresponses support the hypothesis of the presence of “strong cooperation” between psychic andimmune domains. It supports earlier hypothesis that we are monitoring

  • 113.
    Sundström, David
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Quality Technology and Management, Mechanical Engineering and Mathematics.
    On a bioenergetic four compartment model for human exercise2016In: Sports Engineering, ISSN 1369-7072, E-ISSN 1460-2687, Vol. 19, no 4, p. 251-263Article in journal (Refereed)
    Abstract [en]

    Bioenergetic models for exercise performance simulations and pacing strategy optimizations currently lag behind empirical knowledge in human bioenergetics. Therefore, the objective of this study was the construction of a four compartment bioenergetic model that incorporates separate oxidative phosphorylation of lipids and carbohydrates and describes the regulation of these energy substrates’ utilization. Furthermore, the aim was also to model efficiency and the impact of muscle fatigue and the force-velocity relationship on the maximal attainable rate of energy expenditure. The model was formulated with five systems of differential equations that regulated the fluid levels in three of the compartments, while the lipid compartment energy was kept constant. Regulations had to be imposed on the system of compartments to achieve the desired carbohydrate dependent functionality and efficiency of the model. Equilibrium equations were modeled for the alactic compound composition and a constraint was modeled for the maximal energy expenditure rate, dependent on the intramuscular inorganic phosphate. A separate force-velocity relationship was modeled to constrain power output at low speeds and efficiency was modeled with a linear but off-set relationship between power output and rate of energy expenditure. The relative aerobic contribution to total energy expenditure showed good congruence with empirical results, while time to exhaustion was overestimated due to the constraint on maximal rate of energy expenditure. Therefore, further experimental studies are necessary for complete validation of the model.

  • 114.
    Wedin, J. O.
    et al.
    Sundsvall Cty Hosp, Dept Clin Chem, SE-85186 Sundsvall, Sweden.
    Henriksson, Anders E.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences. Sundsvall Cty Hosp, Dept Clin Chem, SE-85186 Sundsvall, Sweden.
    Postgame elevation of cardiac markers among elite floorball players2015In: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 25, no 4, p. 495-500Article in journal (Refereed)
    Abstract [en]

    Cardiac biomarker release after exercise is well documented in endurance sports, but neither the impact of intermittent high-intensity exercise nor the reproducibility has yet been established. Floorball, a popular sport in Scandinavia, involves intermittent periods of high-intensity exercise. This study aimed to determine the prevalence and reproducibility of elevated cardiac marker levels among elite floorball players after two games. Twenty-three healthy male elite floorball players of median age 19 years (range 16-34 years) participated in two standard games. Blood was drawn at three time points: pregame, immediately after, and 2h after the game. Creatine kinase MB (CK-MB), myoglobin, and high-sensitivity cardiac troponin T (hs-cTnT) were measured. The results showed significantly elevated median postgame values in all markers. In both games, hs-cTnT exceeded the cutoff for myocardial damage (14ng/L) 2h postgame in the same six players. The major findings were that postgame cardiac hs-cTnT values among elite floorball players were significantly elevated and reproducible. The findings imply that extended investigations should incorporate evaluation of myocardial function and myocardial perfusion during exercise to seek the clinical significance and underlying mechanisms of elevated cardiac troponin after high-intensity exercise.

  • 115.
    Ørtenblad, Niels
    et al.
    University of Southern Denmark, Odense, Denmark.
    Nielsen, Joachim
    University of Southern Denmark, Odense, Denmark.
    Saltin, Bengt
    Copenhagen Muscle Research Centre, Copenhagen, Denmark.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Role of glycogen availability in sarcoplasmic reticulum Ca(2+) kinetics in human skeletal muscle2011In: Journal of Physiology, ISSN 0022-3751, E-ISSN 1469-7793, Vol. 589, no 3, p. 711-725Article in journal (Refereed)
    Abstract [en]

    Little is known about the precise mechanism that relates skeletal muscle glycogen to muscle fatigue. The aim of the present study was to examine the effect of glycogen on sarcoplasmic reticulum (SR) function in the arm and leg muscles of elite cross-country skiers (n = 10, (V) over dot(O2 max) 72 +/- 2 ml kg(-1) min(-1)) before, immediately after, and 4 h and 22 h after a fatiguing 1 h ski race. During the first 4 h recovery, skiers received either water or carbohydrate (CHO) and thereafter all received CHO-enriched food. Immediately after the race, arm glycogen was reduced to 31 +/- 4% and SR Ca2+ release rate decreased to 85 +/- 2% of initial levels. Glycogen noticeably recovered after 4 h recovery with CHO (59 +/- 5% initial) and the SR Ca2+ release rate returned to pre-exercise levels. However, in the absence of CHO during the first 4 h recovery, glycogen and the SR Ca2+ release rate remained unchanged (29 +/- 2% and 77 +/- 8%, respectively), with both parameters becoming normal after the remaining 18 h recovery with CHO. Leg muscle glycogen decreased to a lesser extent (71 +/- 10% initial), with no effects on the SR Ca2+ release rate. Interestingly, transmission electron microscopy (TEM) analysis revealed that the specific pool of intramyofibrillar glycogen, representing 10-15% of total glycogen, was highly significantly correlated with the SR Ca2+ release rate. These observations strongly indicate that low glycogen and especially intramyofibrillar glycogen, as suggested by TEM, modulate the SR Ca2+ release rate in highly trained subjects. Thus, low glycogen during exercise may contribute to fatigue by causing a decreased SR Ca2+ release rate.

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