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  • 1. Andersson, Johan
    et al.
    Linér, Mats
    Fredsted, Anne
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Cardiovascular and respiratory responses to apneas with and without face immersion in exercising humans2004In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 96, no 3, p. 1005-1010Article in journal (Refereed)
    Abstract [en]

    The effect of the diving response on alveolar gas exchange was investigated in 15 subjects. During steady-state exercise (80 W) on a cycle ergometer, the subjects performed 40-s apneas in air and 40-s apneas with face immersion in cold (10degreesC) water. Heart rate decreased and blood pressure increased during apneas, and the responses were augmented by face immersion. Oxygen uptake from the lungs decreased during apnea in air (-22% compared with eupneic control) and was further reduced during apnea with face immersion (-25% compared with eupneic control). The plasma lactate concentration increased from control (11%) after apnea in air and even more after apnea with face immersion (20%), suggesting an increased anaerobic metabolism during apneas. The lung oxygen store was depleted more slowly during apnea with face immersion because of the augmented diving response, probably including a decrease in cardiac output. Venous oxygen stores were probably reduced by the cardiovascular responses. The turnover times of these gas stores would have been prolonged, reducing their effect on the oxygen uptake in the lungs. Thus the human diving response has an oxygen-conserving effect.

  • 2.
    Andersson, Johan P.A.
    et al.
    Department of Animal Physiology, Lund University.
    Linér, Mats H.
    Lund University Hospital.
    Rünow, Elisabeth
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Diving response and arterial oxygen saturation during apnea and exercise in breath-hold divers2002In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 93, no 3, p. 882-886Article in journal (Refereed)
    Abstract [en]

    This study addressed the effects of apnea in air and apnea with face immersion in cold water (10°C) on the diving response and arterial oxygen saturation during dynamic exercise. Eight trained breath-hold divers performed steady-state exercise on a cycle ergometer at 100 W. During exercise, each subject performed 30-s apneas in air and 30-s apneas with face immersion. The heart rate and arterial oxygen saturation decreased and blood pressure increased during the apneas. Compared with apneas in air, apneas with face immersion augmented the heart rate reduction from 21 to 33% (P < 0.001) and the blood pressure increase from 34 to 42% (P < 0.05). The reduction in arterial oxygen saturation from eupneic control was 6.8% during apneas in air and 5.2% during apneas with face immersion (P < 0.05). The results indicate that augmentation of the diving response slows down the depletion of the lung oxygen store, possibly associated with a larger reduction in peripheral venous oxygen stores and increased anaerobiosis. This mechanism delays the fall in alveolar and arterial Po2 and, thereby, the development of hypoxia in vital organs. Accordingly, we conclude that the human diving response has an oxygen-conserving effect during exercise.

  • 3. Apple, F.S
    et al.
    Tesch, P.A
    CK and LD isozymes in human single muscle fibers in trained athletes1989In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 66, no 6, p. 2717-2720Article in journal (Refereed)
  • 4. Berg, H.E
    et al.
    Dudley, G.A
    Häggmark, T
    Ohlsén, H
    Tesch, P.A
    Effects of lower limb unloading on skeletal muscle mass and function in humans1991In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 70, no 4, p. 1882-1885Article in journal (Refereed)
  • 5. Berg, H.E
    et al.
    Larsson, L.L
    Tesch, P.A
    Lower limb skeletal muscle function after 6 wk of bed rest1997In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 82, no 1, p. 182-188Article in journal (Refereed)
  • 6. Eiken, O
    et al.
    Hesser, C.M
    Thorsson, A
    Lind, F
    Tesch, P.A
    Human skeletal muscle function and metabolism during intense exercise at high oxygen and nitrogen pressures1987In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 63, no 2, p. 571-575Article in journal (Refereed)
  • 7.
    Ekman, C.
    et al.
    Lund Univ, Malmo Univ Hosp, Clin Res Ctr, Dept Clin Sci, Malmo, Sweden..
    Elgzyri, T.
    Lund Univ, Malmo Univ Hosp, Clin Res Ctr, Dept Clin Sci, Malmo, Sweden..
    Ström, Kristoffer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Almgren, P.
    Lund Univ, Malmo Univ Hosp, Clin Res Ctr, Dept Clin Sci, Malmo, Sweden..
    Parikh, H.
    Lund Univ, Malmo Univ Hosp, Clin Res Ctr, Dept Clin Sci, Malmo, Sweden.;NCI, Lab Translat Gen, Div Canc Epidemiol & Genet, NIH, Bethesda, MD 20892 USA..
    Nitert, Marloes Dekker
    Lund Univ, Malmo Univ Hosp, Clin Res Ctr, Dept Clin Sci, Malmo, Sweden..
    Ronn, T.
    Lund Univ, Malmo Univ Hosp, Clin Res Ctr, Dept Clin Sci, Malmo, Sweden..
    Koivula, Fiona Manderson
    Lund Univ, Div Physiotherapy, Dept Hlth Sci, Lund, Sweden..
    Ling, C.
    Lund Univ, Malmo Univ Hosp, Clin Res Ctr, Dept Clin Sci, Malmo, Sweden..
    Tornberg, A. B.
    Lund Univ, Div Physiotherapy, Dept Hlth Sci, Lund, Sweden.;Lund Univ, Genet Mol Epidemiol Unit, Ctr Diabet, Clin Res Ctr, Malmo, Sweden..
    Wollmer, P.
    Lund Univ, Div Physiotherapy, Dept Hlth Sci, Lund, Sweden.;Lund Univ, Dept Clin Sci, Clin Physiol & Nucl Med Unit, Malmo, Sweden..
    Eriksson, K. F.
    Lund Univ, Malmo Univ Hosp, Clin Res Ctr, Dept Clin Sci, Malmo, Sweden..
    Groop, L.
    Lund Univ, Malmo Univ Hosp, Clin Res Ctr, Dept Clin Sci, Malmo, Sweden..
    Hansson, O.
    Lund Univ, Malmo Univ Hosp, Clin Res Ctr, Dept Clin Sci, Malmo, Sweden..
    Less pronounced response to exercise in healthy relatives to type 2 diabetic subjects compared with controls2015In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 119, no 9, p. 953-960Article in journal (Refereed)
    Abstract [en]

    Healthy first-degree relatives with heredity of type 2 diabetes (FH+) are known to have metabolic inflexibility compared with subjects without heredity for diabetes (FH-). In this study, we aimed to test the hypothesis that FH+ individuals have an impaired response to exercise compared with FH-. Sixteen FH+ and 19 FH- insulin-sensitive men similar in age, peak oxygen consumption ((V) over dot(O2 peak)), and body mass index completed an exercise intervention with heart rate monitored during exercise for 7 mo. Before and after the exercise intervention, the participants underwent a physical examination and tests for glucose tolerance and exercise capacity, and muscle biopsies were taken for expression analysis. The participants attended, on average, 39 training sessions during the intervention and spent 18.8 MJ on exercise. (V) over dot(O2 peak)/kg increased by 14%, and the participants lost 1.2 kg of weight and 3 cm waist circumference. Given that the FH- group expended 61% more energy during the intervention, we used regression analysis to analyze the response in the FH+ and FH- groups separately. Exercise volume had a significant effect on (V) over dot(O2 peak), weight, and waist circumference in the FH- group, but not in the FH+ group. After exercise, expression of genes involved in metabolism, oxidative phosphorylation, and cellular respiration increased more in the FH- compared with the FH+ group. This suggests that healthy, insulin-sensitive FH+ and FH- participants with similar age, (V) over dot(O2 peak), and body mass index may respond differently to an exercise intervention. The FH+ background might limit muscle adaptation to exercise, which may contribute to the increased susceptibility to type 2 diabetes in FH+ individuals.

  • 8.
    Elmer, Steven
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Eccentric arm cycling: physiological responses and potential applications for clinical andathletic populations2013In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 113, no 10, p. 2541-2552Article in journal (Refereed)
    Abstract [en]

    INTRODUCTION:Eccentric leg cycling has served as an important research model for investigating multi-joint eccentric actions and as an effective rehabilitation and training modality for improving locomotor muscle function (e.g., quadriceps size, strength, mobility). While there are more than 30 reports documenting physiological responses to eccentric leg cycling, physiological responses to eccentric arm cycling (ECarm) have not been clearly established.

    PURPOSE:We tested the hypothesis that ECarm could be performed with lower levels of metabolic and cardiorespiratory demand and perceived exertion compared to traditional concentric arm cycling (CCarm).

    METHODS:Eight individuals performed ECarm and CCarm at 40, 80, and 120 W (~9 min, 60 rpm) while expired gases and muscle activation patterns were recorded.

    RESULTS:Oxygen consumption, cardiac output, heart rate, and ventilation were 25-50 % lower during ECarm compared to CCarm (all P < 0.05). Further, only low-to-moderate levels of whole-body and arm-specific perceived exertion were required to perform ECarm which was not the case for CCarm (8-12 vs. 9-16 Borg values, both P < 0.05). Differences in oxygen consumption and total upper body muscle activity between ECarm and CCarm were strongly related (r (2) = 0.75, P < 0.01). Coordination of ECarm involved triceps brachii, deltoideus anterior, and external oblique muscles, whereas CCarm involved all of these muscles along with contributions from biceps brachii, deltoideus posterior, and trapezius transversalis.

    CONCLUSIONS:These results highlight the high-force, low-cost nature of multi-joint eccentric actions and extend the application of eccentric cycling to the upper body. ECarm may be useful for exercising elbow, trunk, and shoulder musculature while minimizing metabolic and cardiorespiratory strain and perceived exertion.

  • 9.
    Fredsted, A.
    et al.
    Aarhus Univ, Dept Biomed, DK-8000 Aarhus C, Denmark.
    Gissel, H.
    Aarhus Univ, Dept Biomed, DK-8000 Aarhus C, Denmark.
    Örtenblad, Niels
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Clausen, T.
    Aarhus Univ, Dept Biomed, DK-8000 Aarhus C, Denmark.
    Effects of beta(2)-agonists on force during and following anoxia in rat extensor digitorum longus muscle2012In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 112, no 12, p. 2057-2067Article in journal (Refereed)
    Abstract [en]

    Fredsted A, Gissel H, Ortenblad N, Clausen T. Effects of beta(2)-agonists on force during and following anoxia in rat extensor digitorum longus muscle. J Appl Physiol 112: 2057-2067, 2012. First published April 5, 2012; doi:10.1152/japplphysiol.01558.2011.-Electrical stimulation of isolated muscles may lead to membrane depolarization, gain of Na+, loss of K+ and fatigue. These effects can be counteracted with beta(2)-agonists possibly via activation of the Na+-K+ pumps. Anoxia induces loss of force; however, it is not known whether beta(2)-agonists affect force and ion homeostasis in anoxic muscles. In the present study isolated rat extensor digitorum longus (EDL) muscles exposed to anoxia showed a considerable loss of force, which was markedly reduced by the beta(2)-agonists salbutamol (10(-6) M) and terbutaline (10(-6) M). Intermittent stimulation (15-30 min) clearly increased loss of force during anoxia and reduced force recovery during reoxygenation. The beta(2)-agonists salbutamol (10(-7)-10(-5) M) and salmeterol (10(-6) M) improved force development during anoxia (25%) and force recovery during reoxygenation (55-262%). The effects of salbutamol on force recovery were prevented by blocking the Na+-K+ pumps with ouabain or by blocking glycolysis with 2-deoxyglucose. Dibutyryl cAMP (1 mM) or theophylline (1 mM) also improved force recovery remarkably. In anoxic muscles, salbutamol decreased intracellular Na+ and increased Rb-86 uptake and K+ content, indicating stimulation of the Na+-K+ pumps. In fatigued muscles salbutamol induced recovery of excitability. Thus beta(2)-agonists reduce the anoxia-induced loss of force, leading to partial force recovery. These data strongly suggest that this effect is mediated by cAMP stimulation of the Na+-K+ pumps and that it is not related to recovery of energy status (PCr, ATP, lactate).

  • 10. Gustafsson, T.
    et al.
    Osterlund, T.
    Flanagan, J. N.
    von Walden, F.
    Trappe, T. A.
    Linnehan, R. M.
    Tesch, Per A.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Effects of 3 days unloading on molecular regulators of muscle size in humans2010In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 109, no 3, p. 721-727Article in journal (Refereed)
    Abstract [en]

    Gustafsson T, Osterlund T, Flanagan JN, von Walden F, Trappe TA, Linnehan RM, Tesch PA. Effects of 3 days unloading on molecular regulators of muscle size in humans. J Appl Physiol 109: 721-727, 2010. First published June 10, 2010; doi: 10.1152/japplphysiol.00110.2009.-Changes in skeletal muscle mass are controlled by mechanisms that dictate protein synthesis or degradation. The current human study explored whether changes in activation of the phosphoinositide 3-kinase (PI3K)-Akt1, p38, myostatin, and mRNA expression of markers of protein degradation and synthesis occur soon after withdrawal of weight bearing. Biopsies of the vastus lateralis muscle (VL) and soleus muscle (Sol) were obtained from eight healthy men before and following 3 days of unilateral lower limb suspension (ULLS). Akt1, Forkhead box class O (FOXO)-1A, FOXO-3A, p38, and eukaryotic translation initiation factor 4E binding protein 1 (4E-BP1) phosphorylation and protein levels and myostatin protein level were analyzed by Western blot. Levels of mRNA of IGF1, FOXO-1A, FOXO-3A, atrogin-1, MuRF-1, caspase-3, calpain-2, calpain-3, 4E-BP1, and myostatin were measured using real-time PCR. The amounts of phosphorylated Akt1, FOXO-1A, FOXO-3A, and p38 were unaltered (P > 0.05) after ULLS. Similarly, mRNA levels of IGF1, FOXO-1A, FOXO-3A, caspase-3, calpain-2, and calpain-3 showed no changes (P > 0.05). The mRNA levels of atrogin-1 and MuRF-1, as well as the mRNA and protein phosphorylation of 4E-BP1, increased (P < 0.05) in VL but not in Sol. Both muscles showed increased (P < 0.05) myostatin mRNA and protein following ULLS. These results suggest that pathways other than PI3K-Akt stimulate atrogin-1 and MuRF-1 expression within 3 days of ULLS. Alternatively, transient changes in these pathways occurred in the early phase of ULLS. The increased myostatin mRNA and protein expression also indicate that multiple processes are involved in the early phase of muscle wasting. Further, the reported difference in gene expression pattern across muscles suggests that mechanisms regulating protein content in human skeletal muscle are influenced by phenotype and/or function.

  • 11. Hather, B.M
    et al.
    Adams, G.A
    Tesch, P.A
    Dudley, G.A
    Skeletal muscle responses to lower limb suspensions in humans1992In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 72, no 4, p. 1493-1498Article in journal (Refereed)
  • 12.
    Hostrup, Morten
    et al.
    Univ Copenhagen, Dept Nutr Exercise & Sports, Sect Integrated Physiol, DK-2100 Copenhagen, Denmark.;Bispebjerg Hosp, Dept Resp Res, Copenhagen, Denmark..
    Kalsen, Anders
    Univ Copenhagen, Dept Nutr Exercise & Sports, Sect Integrated Physiol, DK-2100 Copenhagen, Denmark.;Bispebjerg Hosp, Dept Resp Res, Copenhagen, Denmark..
    Onslev, Johan
    Univ Copenhagen, Dept Nutr Exercise & Sports, Sect Integrated Physiol, DK-2100 Copenhagen, Denmark.;Bispebjerg Hosp, Dept Resp Res, Copenhagen, Denmark..
    Jessen, Soren
    Univ Copenhagen, Dept Nutr Exercise & Sports, Sect Integrated Physiol, DK-2100 Copenhagen, Denmark.;Bispebjerg Hosp, Dept Resp Res, Copenhagen, Denmark..
    Haase, Christoffer
    Bispebjerg Hosp, Dept Resp Res, Copenhagen, Denmark..
    Habib, Sajad
    Univ Copenhagen, Dept Nutr Exercise & Sports, Sect Integrated Physiol, DK-2100 Copenhagen, Denmark..
    Örtenblad, Niels
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. Univ Southern Denmark, Dept Sports Sci & Biomech, Odense, Denmark.;Mid Sweden Univ, Swedish Winter Sports Res Ctr, Sundsvall, Sweden..
    Backer, Vibeke
    Bispebjerg Hosp, Dept Resp Res, Copenhagen, Denmark..
    Bangsbo, Jens
    Univ Copenhagen, Dept Nutr Exercise & Sports, Sect Integrated Physiol, DK-2100 Copenhagen, Denmark..
    Mechanisms underlying enhancements in muscle force and power output during maximal cycle ergometer exercise induced by chronic beta(2)-adrenergic stimulation in men2015In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 119, no 5, p. 475-486Article in journal (Refereed)
    Abstract [en]

    The study was a randomized placebo-controlled trial investigating mechanisms by which chronic beta(2)-adrenergic stimulation enhances muscle force and power output during maximal cycle ergometer exercise in young men. Eighteen trained men were assigned to an experimental group [oral terbutaline 5 mg/30 kg body weight (bw) twice daily (TER); n = 9] or a control group [placebo (PLA); n = 9] for a 4-wk intervention. No changes were observed with the intervention in PLA. Isometric muscle force of the quadriceps increased (P <= 0.01) by 97 +/- 29 N (means +/- SE) with the intervention in TER compared with PLA. Peak and mean power output during 30 s of maximal cycling increased (P <= 0.01) by 32 +/- 8 and 25 +/- 9 W, respectively, with the intervention in TER compared with PLA. Maximal oxygen consumption ((V) over dotO(2)max) and time to fatigue during incremental cycling did not change with the intervention. Lean body mass increased by 1.95 +/- 0.8 kg (P <= 0.05) with the intervention in TER compared with PLA. Change in single fiber cross-sectional area of myosin heavy chain (MHC) I (1,205 +/- 558 mu m(2); P <= 0.01) and MHC II fibers (1,277 +/- 595 mu m(2); P <= 0.05) of the vastus lateralis muscle was higher for TER than PLA with the intervention, whereas no changes were observed in MHC isoform distribution. Expression of muscle proteins involved in growth, ion handling, lactate production, and clearance increased (P <= 0.05) with the intervention in TER compared with PLA, with no change in oxidative enzymes. Our observations suggest that muscle hypertrophy is the primary mechanism underlying enhancements in muscle force and peak power during maximal cycling induced by chronic beta(2-)adrenergic stimulation in humans.

  • 13. Jacobs, I
    et al.
    Tesch, P.A
    Bar-Or, O
    Karlsson, J
    Dotan, J
    Lactate in human skeletal muscle after 10 s of supramaximal exercise1983In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 55, no 2, p. 365-367Article in journal (Refereed)
  • 14.
    Lundberg, Tommy
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Fernandez-Gonzalo, Rodrigo
    Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
    Gustafsson, Thomas
    Department of Laboratory Medicine, Section for Clinical Physiology, Karolinska University Hospital, Stockholm, Sweden.
    Tesch, Per
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Aerobic exercise does not compromise muscle hypertrophy response to short-term resistance training2013In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 114, no 1, p. 81-89Article in journal (Refereed)
    Abstract [en]

    This study tested the hypothesis that chronic aerobic and resistance exercise (AE+RE) would elicit greater muscle hypertrophy than resistance exercise only (RE). Ten men (25±4 yrs) performed 5 wks unilateral knee extensor AE+RE. The opposing limb was subjected to RE. AE completed 6 hrs prior to RE, consisted of ~45 min one-legged cycle ergometry. RE comprised 4 x 7 maximal concentric-eccentric knee extensions. Various indices of in vivo knee extensor function were measured before and after training. Magnetic resonance imaging (MRI) assessed m. quadricep femoris (QF) cross-sectional area (CSA), volume, and signal intensity (SI). Biopsies obtained from m. vastus lateralis determined fiber CSA, enzyme levels and gene expression of myostatin, atrogin-1, MuRF-1, PGC-1α and VEGF. Increases (P < 0.05) in isometric strength and peak power, respectively were comparable in AE+RE (9 and 29%) and RE (11 and 24%). AE+RE showed greater increase (14%; P < 0.05) in QF volume than RE (8%). Muscle fiber CSA increased 17% after AE+RE (P < 0.05) and 9% after RE (P > 0.05). QF SI increased (12%; P < 0.05) after AE+RE, but not RE. Neither AE+RE nor RE showed altered mRNA-levels. Citrate Synthase activity increased (P < 0.05) after AE+RE. The results suggest that the increased aerobic capacity shown with AE+RE, was accompanied by a more robust increase in muscle size compared with RE. While this response was not carried over to greater improvement in muscle function, it remains that intense AE can be executed prior to RE without compromising performance outcome.

  • 15.
    Lundberg, Tommy
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Fernandez-Gonzalo, Rodrigo
    Karolinska Institutet.
    Tesch, Per
    Karolinska Institutet.
    Exercise-induced AMPK activation does not interfere with muscle hypertrophy in response to resistance training in men2014In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 116, no 6, p. 611-620Article in journal (Refereed)
    Abstract [en]

    As aerobic exercise (AE) may interfere with adaptations to resistance exercise (RE), this study explored acute and chronic responses to consecutive AE (similar to 45 min cycling) and RE (4 X 7 maximal knee extensions) vs. RE only. Ten men performed acute unilateral AE + RE interspersed by 15 min recovery. The contralateral leg was subjected to RE. This exercise paradigm was then implemented in a 5-wk training program. Protein phosphorylation, gene expression, and glycogen content were assessed in biopsies obtained from the vastus lateralis muscle of both legs immediately before and 3 h after acute RE. Quadriceps muscle size and in vivo torque were measured, and muscle samples were analyzed for citrate synthase activity and glycogen concentration, before and after training. Acute AE reduced glycogen content (32%; P < 0.05) and increased (P < 0.05) phosphorylation of AMPK (1.5-fold) and rpS6 (1.3-fold). Phosphorylation of p70S6K and 4E-BP1 remained unchanged. Myostatin gene expression was downregulated after acute AE + RE but not RE. Muscle size showed greater (P < 0.05) increase after AE + RE (6%) than RE (3%) training. Citrate synthase activity (18%) and endurance performance (22%) increased (P < 0.05) after AE + RE but not RE. While training increased (P < 0.05) in vivo muscle strength in both legs, normalized and concentric torque increased after RE only. Thus AE activates AMPK, reduces glycogen stores, and impairs the progression of concentric force, yet muscle hypertrophic responses to chronic RE training appear not to be compromised.

  • 16. Norman, Barbara
    et al.
    Esbjörnsson, Mona
    Rundqvist, Håkan
    Österlund, Ted
    Von Walden, Ferdinand
    Tesch, Per A
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Strength, power, fiber types, and mRNA expression in trained men and women with different ACTN3 R577X genotypes2009In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 106, p. 959-965Article in journal (Refereed)
    Abstract [en]

    .-alpha-Actinins are structural proteins of the Z-line. Human skeletal muscle expresses two alpha-actinin isoforms, alpha-actinin-2 and alpha-actinin-3, encoded by their respective genes ACTN2 and ACTN3. ACTN2 is expressed in all muscle fiber types, while only type II fibers, and particularly the type IIb fibers, express ACTN3. ACTN3 (R577X) polymorphism results in loss of alpha-actinin-3 and has been suggested to influence skeletal muscle function. The X allele is less common in elite sprint and power athletes than in the general population and has been suggested to be detrimental for performance requiring high power. The present study investigated the association of ACTN3 genotype with muscle power during 30-s Wingate cycling in 120 moderately to well-trained men and women and with knee extensor strength and fatigability in a subset of 21 men performing isokinetic exercise. Muscle biopsies were obtained from the vastus lateralis muscle to determine fiber-type composition and ACTN2 and ACTN3 mRNA levels. Peak and mean power and the torque-velocity relationship and fatigability output showed no difference across ACTN3 genotypes. Thus this study suggests that R577X polymorphism in ACTN3 is not associated with differences in power output, fatigability, or force-velocity characteristics in moderately trained individuals. However, repeated exercise bouts prompted an increase in peak torque in RR but not in XX genotypes, suggesting that ACTN3 genotype may modulate responsiveness to training. Our data further suggest that alpha-actinins do not play a significant role in determining muscle fiber-type composition. Finally, we show that ACTN2 expression is affected by the content of alpha-actinin-3, which implies that alpha-actinin-2 may compensate for the lack of alpha-actinin-3 and hence counteract the phenotypic consequences of the deficiency.

  • 17.
    Perez-Suarez, Ismael
    et al.
    Univ. Campus of Tafira, Las Palmas de Gran Canaria, Canary Islands, Spain; Research Institute of Biomedical and Health Sciences, Las Palmas de Gran Canaria, Spain.
    Ponce-González, Jesús G.
    Univ. Campus of Tafira, Las Palmas de Gran Canaria, Canary Islands, Spain.
    De La Calle-Herrero, Jaime
    Univ. Campus of Tafira, Las Palmas de Gran Canaria, Canary Islands, Spain.
    Losa-Reyna, Jose
    Univ. Campus of Tafira, Las Palmas de Gran Canaria, Canary Islands, Spain.
    Martin-Rincon, Marcos
    Univ. Campus of Tafira, Las Palmas de Gran Canaria, Canary Islands, Spain; Research Institute of Biomedical and Health Sciences, Las Palmas de Gran Canaria, Spain.
    Morales-Alamo, David
    Univ. Campus of Tafira, Las Palmas de Gran Canaria, Canary Islands, Spain; Research Institute of Biomedical and Health Sciences, Las Palmas de Gran Canaria, Spain.
    Santana, Alfredo
    Complejo Hospitalario Universitario Insular-Materno Infantil de Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Calbet, Jose A. L.
    Univ. Campus of Tafira, Las Palmas de Gran Canaria, Canary Islands, Spain; Research Institute of Biomedical and Health Sciences, Las Palmas de Gran Canaria, Spain.
    Severe energy deficit upregulates leptin receptors, leptin signaling, and PTP1B in human skeletal muscle2017In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 123, no 5, p. 1276-1287Article in journal (Refereed)
    Abstract [en]

    In obesity, leptin receptors (OBR) and leptin signaling in skeletal muscle are downregulated. To determine whether OBR and leptin signaling are upregulated with a severe energy deficit, 15 overweight men were assessed before the intervention (PRE), after 4 days of caloric restriction (3.2 kcal·kg body wt-1·day-1) in combination with prolonged exercise (CRE; 8 h walking + 45 min single-arm cranking/day) to induce an energy deficit of ~5,500 kcal/day, and following 3 days of control diet (isoenergetic) and reduced exercise (CD). During CRE, the diet consisted solely of whey protein (n = 8) or sucrose (n = 7; 0.8 g·kg body wt-1·day-1). Muscle biopsies were obtained from the exercised and the nonexercised deltoid muscles and from the vastus lateralis. From PRE to CRE, serum glucose, insulin, and leptin were reduced. OBR expression was augmented in all examined muscles associated with increased maximal fat oxidation. Compared with PRE, after CD, phospho-Tyr1141, phospho-Tyr985OBR, JAK2, and phospho- Tyr1007/1008JKK2protein expression were increased in all muscles, whereas STAT3 and phospho-Tyr705STAT3 were increased only in the arms. The expression of protein tyrosine phosphatase 1B (PTP1B) in skeletal muscle was increased by 18 and 45% after CRE and CD, respectively (P &lt; 0.05). Suppressor of cytokine signaling 3 (SOCS3) tended to increase in the legs and decrease in the arm muscles (ANOVA interaction: P &lt; 0.05). Myosin heavy chain I isoform was associated with OBR protein expression (r-=0.75), phospho- Tyr985OBR (r = 0.88), and phospho-Tyr705STAT3/STAT3 (r = 0.74). In summary, despite increased PTP1B expression, skeletal muscle OBR and signaling are upregulated by a severe energy deficit with greater response in the arm than in the legs likely due to SOCS3 upregulation in the leg muscles NEW &amp; NOTEWORTHY This study shows that the skeletal muscle leptin receptors and their corresponding signaling cascade are upregulated in response to a severe energy deficit, contributing to increase maximal fat oxidation. The responses are more prominent in the arm muscles than in the legs but partly blunted by whey protein ingestion and high volume of exercise. This occurs despite an increase of protein tyrosine phosphatase 1B protein expression, a known inhibitor of insulin and leptin signaling.

  • 18. Plouts-Snyder, L.L
    et al.
    Tesch, P.A
    Biro, R.L
    Dudley, G.A
    Effect of resistance training on muscle use during exercise1994In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 75, no 6, p. 1675-1681Article in journal (Refereed)
  • 19. Ploutz-Snyder, L.L
    et al.
    Tesch, P.A
    Crittenden, D
    Dudley, G.A
    Effect of unweighting on skeletal muscle use during exercise1995In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 79, no 1, p. 168-175Article in journal (Refereed)
  • 20.
    Psilander, Niklas
    et al.
    Swedish School of Sport and Health Sciences, Stockholm.
    Eftestøl, Einar
    University of Oslo, Oslo, Norway.
    Cumming, Kristoffer T.
    Norwegian School of Sport Sciences, Oslo, Norway.
    Juvkam, Inga
    University of Oslo, Oslo, Norway.
    Ekblom, Maria M.
    Swedish School of Sport and Health Sciences, Stockholm, Sweden.
    Sunding, Kerstin
    Karolinska Institutet, Stockholm.
    Wernbom, Mathias
    University of Gothenburg, Gothenburg, Sweden.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, Stockholm.
    Bruusgaard, Jo C.
    University of Oslo, Oslo, Norway; Kristiania University College, Oslo, Norway.
    Raastad, Truls
    Norwegian School of Sport Sciences, Oslo, Norway.
    Gundersen, Kristian
    University of Oslo, Oslo, Norway.
    Effects of training, detraining, and retraining on strength, hypertrophy, and myonuclear number in human skeletal muscle2019In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 126, no 6, p. 1636-1645Article in journal (Refereed)
    Abstract [en]

    Previously trained mouse muscles acquire strength and volume faster than naïve muscles; it has been suggested that this is related to increased myonuclear density. The present study aimed to determine whether a previously strength-trained leg (mem-leg) would respond better to a period of strength training than a previously untrained leg (con-leg). Nine men and 10 women performed unilateral strength training (T1) for 10 wk, followed by 20 wk of detraining (DT) and a 5-wk bilateral retraining period (T2). Muscle biopsies were taken before and after each training period and analyzed for myonuclear number, fiber volume, and cross-sectional area (CSA). Ultrasound and one repetition of maximum leg extension were performed to determine muscle thickness (MT) and strength. CSA (~17%), MT (~10%), and strength (~20%) increased during T1 in the mem-leg. However, the myonuclear number and fiber volume did not change. MT and CSA returned to baseline values during DT, but strength remained elevated (~60%), supporting previous findings of a long-lasting motor learning effect. MT and strength increased similarly in the mem-leg and con-leg during T2, whereas CSA, fiber volume, and myonuclear number remained unaffected. In conclusion, training response during T2 did not differ between the mem-leg and con-leg. However, this does not discount the existence of human muscle memory, since no increase in the number of myonuclei was detected during T1 and no clear detraining effect was observed for cell size during DT; thus, the present data did not allow for a rigorous test of the muscle memory hypothesis. NEW & NOTEWORTHY If a long-lasting intramuscular memory exists in humans, this will affect strength-training advice for both athletes and the public. Based on animal experiments, we hypothesized that such a memory exists and that it is related to the myonuclear number. However, a period of unilateral strength training, followed by detraining, did not increase the myonuclear number. The training response, during a subsequent bilateral retraining period, was not enhanced in the previously trained leg. 

  • 21.
    Schagatay, Erika
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Andersson, Johan
    Department of Animal Physiology, Lund University.
    Hallén, Magnus
    Department of Surgery, Lund University Hospital, S-221 85 Lund.
    Pålsson, Birger
    Department of Surgery, Lund University Hospital, S-221 85 Lund.
    Selected Contribution: Role of spleen emptying in prolonging apneas in humans2001In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 90, no 4, p. 1623-1629Article in journal (Refereed)
    Abstract [en]

    This study addressed the interaction between short-term adaptation to apneas with face immersion and erythrocyte release from the spleen. Twenty healthy volunteers, including ten splenectomized subjects, participated. After prone rest, they performed five maximal-duration apneas with face immersion in 10°C water, with 2-min intervals. Cardiorespiratory parameters and venous blood samples were collected. In subjects with spleens, hematocrit and hemoglobin concentration increased by 6.4% and 3.3%, respectively, over the serial apneas and returned to baseline 10 min after the series. A delay of the physiological breaking point of apnea, by 30.5% (17 s), was seen only in this group. These parameters did not change in the splenectomized group. Plasma protein concentration, preapneic alveolar PCO2, inspired lung volume, and diving bradycardia remained unchanged throughout the series in both groups. Serial apneas thus triggered the hematological changes that have been previously observed after long apneic diving shifts; they were rapidly reversed and did not occur in splenectomized subjects. This suggests that splenic contraction occurs in humans as a part of the diving response and may prolong repeated apneas.

  • 22. Tesch, P.A
    et al.
    Kaiser, P
    Effects of β-adrenergic blockade on oxygen consumption during submaximal and maximal exercise1983In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 54, p. 901-905Article in journal (Refereed)
  • 23. Tesch, P.A
    et al.
    Karlsson, J
    Muscle fiber types and size in trained and untrained muscles of athletes1985In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 59, no 6, p. 716-720Article in journal (Refereed)
  • 24. Tesch, P.A
    et al.
    Thorsson, A
    Essén-Gustavsson, B
    Enzyme activitates of FT and ST fibers in heavy-resistance trained athletes1989In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 67, no 1, p. 83-87Article in journal (Refereed)
  • 25. Tesch, P.A
    et al.
    Thorsson, A
    Fujitsuka, N
    Creatine phosphate in fiber types of skeletal muscle before and after exhaustive exercise1989In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 66, no 4, p. 1756-1759Article in journal (Refereed)
  • 26. Tesch, P.A
    et al.
    Thorsson, A
    Kaiser, P
    Muscle capillary supply and fiber type characteristics in weight- and powerlifters1984In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 56, no 1, p. 35-39Article in journal (Refereed)
  • 27.
    Tesch, Per
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Gustafsson, T
    von Walden, F
    Linnehlan, R M
    Trappe, T A
    Reliability of results and interpretation of measures of 3-methylhistidine in muscle interstitium as marker of muscle proteolysis - Reply to Rennie, Phillips, and Smith: Letter2008In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 105, no 4, p. 1382-1383Article in journal (Other academic)
  • 28.
    Tesch, Per
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    von Walden, Ferdinand
    Gustafsson, Thomas
    Linnehan, Richard M
    Trappe, Todd A
    Skeletal muscle proteolysis in response to short-term unloading in humans2008In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 105, no 3, p. 902-906Article in journal (Refereed)
    Abstract [en]

    Skeletal muscle atrophy is evident after muscle disuse, unloading,or spaceflight and results from decreased protein content asa consequence of decreased protein synthesis, increased proteinbreakdown or both. At this time, there are essentially no humandata describing proteolysis in skeletal muscle undergoing atrophyon Earth or in space, primarily due to lack of valid and accuratemethodology. This particular study aimed at assessing the effectsof short-term unloading on the muscle contractile proteolysisrate. Eight men were subjected to 72-h unilateral lower limbsuspension (ULLS) and intramuscular interstitial levels of thenaturally occurring proteolytic tracer 3-methylhistidine (3MH)were measured by means of microdialysis before and on completionof this intervention. The 3MH concentration following 72-h ULLS(2.01 ± 0.22 nmol/ml) was 44% higher (P < 0.05) thanbefore ULLS (1.56 ± 0.20 nmol/ml). The present experimentalmodel and the employed method determining 3MH in microdialysatespresent a promising tool for monitoring skeletal muscle proteolysisor metabolism of specific muscles during conditions resultingin atrophy caused by, e.g., disuse and real or simulated microgravity.This study provides evidence that the atrophic processes areevoked rapidly and within 72 h of unloading and suggests thatcountermeasures should be employed in the early stages of spacemissions to offset or prevent muscle loss during the periodwhen the rate of muscle atrophy is the highest.

     

  • 29.
    Trappe, S
    et al.
    Human Performance Laboratory, Ball State Univ., Muncie, IN 47306, United States.
    Hayes, A
    Human Performance Laboratory, Ball State Univ., Muncie, IN 47306, United States.
    Galpin, L
    Human Performance Laboratory, Ball State Univ., Muncie, IN 47306, United States.
    Kaminsky, L
    Human Performance Laboratory, Ball State Univ., Muncie, IN 47306, United States.
    Jemiolo, B
    Human Performance Laboratory, Ball State Univ., Muncie, IN 47306, United States.
    Fink, W
    Ball State Univ, Human Performance Lab, Muncie, IN 47306 USA. .
    Trappe, T
    Human Performance Laboratory, Ball State Univ., Muncie, IN 47306, United States.
    Jansson, Anna
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Gustafsson, T
    Department of Laboratory Medicine, Clinical Physiology Karolinska Instutet, Stockholm, Sweden.
    Tesch, Per
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    New Records In Aerobic Power Among Octogenarian Lifelong Endurance Athletes2013In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 114, no 1, p. 3-10Article in journal (Refereed)
    Abstract [en]

    New records in aerobic power among octogenarian lifelong endurance athletes. J Appl Physiol 114: 3-10, 2013. First published October 11, 2012; doi:10.1152/japplphysiol.01107.2012.-We examined whole body aerobic capacity and myocellular markers of oxidative metabolism in lifelong endurance athletes [n = 9, 81 ± 1 yr, 68 ± 3 kg, body mass index (BMI) = 23 ± 1 kg/m2] and age-matched, healthy, untrained men (n = 6; 82 ± 1 y, 77 ± 5 kg, BMI = 26 ± 1 kg/m2). The endurance athletes were cross-country skiers, including a former Olympic champion and several national/regional champions, with a history of aerobic exercise and participation in endurance events throughout their lives. Each subject performed a maximal cycle test to assess aerobic capacity (VO2max). Subjects had a resting vastus lateralis muscle biopsy to assess oxidative enzymes (citrate synthase and βHAD) and molecular (mRNA) targets associated with mitochondrial biogenesis [peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) and mitochondrial transcription factor A (Tfam)]. The octogenarian athletes had a higher (P < 0.05) absolute (2.6 ± 0.1 vs. 1.6 ± 0.1 l/min) and relative (38 ± 1 vs. 21 ± 1 ml·kg-1·min-1) VO2max, ventilation (79 ± 3 vs. 64 ± 7 l/min), heart rate (160 ± 5 vs. 146 ± 8 beats per minute), and final workload (182 ± 4 vs. 131 ± 14 W). Skeletal muscle oxidative enzymes were 54% (citrate synthase) and 42% (βHAD) higher (P < 0.05) in the octogenarian athletes. Likewise, basal PGC-1α and Tfam mRNA were 135% and 80% greater (P < 0.05) in the octogenarian athletes. To our knowledge, the VO2max of the lifelong endurance athletes is the highest recorded in humans >80 yr of age and comparable to nonendurance trained men 40 years younger. The superior cardiovascular and skeletal muscle health profile of the octogenarian athletes provides a large functional reserve above the aerobic frailty threshold and is associated with lower risk for disability and mortality. © 2013 the American Physiological Society.

  • 30.
    Tymko, Michael M.
    et al.
    Univ British Columbia, Sch Hlth & Exercise Sci, Ctr Heart Lung & Vasc Hlth, Kelowna, BC, Canada.
    Tremblay, Joshua C.
    Queens Univ, Sch Kinesiol & Hlth Studies, Cardiovasc Stress Response Lab, Kingston, ON, Canada.
    Steinback, Craig D.
    Univ Alberta, Fac Phys Educ & Recreat, Edmonton, AB, Canada.
    Moore, Jonathan P.
    Bangor Univ, Extremes Res Grp, Sch Sport Hlth & Exercise Sci, Bangor, Gwynedd, Wales.
    Hansen, Alex B.
    Univ British Columbia, Sch Hlth & Exercise Sci, Ctr Heart Lung & Vasc Hlth, Kelowna, BC, Canada.
    Patrician, Alexander
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Howe, Connor A.
    Univ British Columbia, Sch Hlth & Exercise Sci, Ctr Heart Lung & Vasc Hlth, Kelowna, BC, Canada.
    Hoiland, Ryan L.
    Univ British Columbia, Sch Hlth & Exercise Sci, Ctr Heart Lung & Vasc Hlth, Kelowna, BC, Canada.
    Green, Daniel J.
    Univ Western Australia, Sch Sports Sci Exercise & Hlth, Crawley, WA, Australia; Liverpool John Moores Univ, Res Inst Sport & Exercise Sci, Liverpool, Merseyside, England.
    Ainslie, Philip N.
    Univ British Columbia, Sch Hlth & Exercise Sci, Ctr Heart Lung & Vasc Hlth, Kelowna, BC, Canada.
    UBC-Nepal Expedition: acute alterations in sympathetic nervous activity do not influence brachial artery endothelial function at sea level and high altitude2017In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 123, no 5, p. 1386-1396Article in journal (Refereed)
    Abstract [en]

    Evidence indicates that increases in sympathetic nervous activity (SNA), and acclimatization to high altitude (HA), may reduce endothelial function as assessed by brachial artery flow-mediated dilatation (FMD); however, it is unclear whether such changes in FMD are due to direct vascular constraint, or consequential altered hemodynamics (e.g., shear stress) associated with increased SNA as a consequence of exposure to HA. We hypothesized that 1) at rest, SNA would be elevated and FMD would be reduced at HA compared with sea-level (SL);and 2) at SL and HA, FMD would be reduced when SNA was acutely increased, and elevated when SNA was acutely decreased. Using a novel, randomized experimental design, brachial artery FMD was assessed at SL (344 m) and HA (5,050 m) in 14 participants during mild lower-body negative pressure (LBNP; -10 mmHg) and lower-body positive pressure (LBPP; -10 mmHg). Blood pressure (finger photoplethysmography), heart rate (electrocardiogram), oxygen saturation (pulse oximetry), and brachial artery blood flow and shear rate (Duplex ultrasound) were recorded during LBNP, control, and LBPP trials. Muscle SNA was recorded (via microneurography) in a subset of participants (n = 5). Our findings were 1) at rest, SNA was elevated (P < 0.01), and absolute FMD was reduced (P = 0.024), but relative FMD remained unaltered (P = 0.061), at HA compared with SL; and 2) despite significantly altering SNA with LBNP (+60.3 +/- 25.5%) and LBPP (-37.2 +/- 12.7%) (P < 0.01), FMD was unaltered at SL (P = 0.448) and HA (P = 0.537). These data indicate that acute and mild changes in SNA do not directly influence brachial artery FMD at SL or HA.

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