Muscle tissue adaptations to hypoxia
Tóm tắt
This review reports on the effects of hypoxia on human skeletal muscle tissue. It was hypothesized in early reports that chronic hypoxia, as the main physiological stress during exposure to altitude, per se might positively affect muscle oxidative capacity and capillarity. However, it is now established that sustained exposure to severe hypoxia has detrimental effects on muscle structure. Short-term effects on skeletal muscle structure can readily be observed after 2 months of acute exposure of lowlanders to severe hypoxia, e.g. during typical mountaineering expeditions to the Himalayas. The full range of phenotypic malleability of muscle tissue is demonstrated in people living permanently at high altitude (e.g. at La Paz, 3600–4000m). In addition, there is some evidence for genetic adaptations to hypoxia in high-altitude populations such as Tibetans and Quechuas, who have been exposed to altitudes in excess of 3500m for thousands of generations. The hallmark of muscle adaptation to hypoxia in all these cases is a decrease in muscle oxidative capacity concomitant with a decrease in aerobic work capacity. It is thought that local tissue hypoxia is an important adaptive stress for muscle tissue in exercise training, so these results seem contra-intuitive. Studies have therefore been conducted in which subjects were exposed to hypoxia only during exercise sessions. In this situation, the potentially negative effects of permanent hypoxic exposure and other confounding variables related to exposure to high altitude could be avoided. Training in hypoxia results, at the molecular level, in an upregulation of the regulatory subunit of hypoxia-inducible factor-1 (HIF-1). Possibly as a consequence of this upregulation of HIF-1, the levels mRNAs for myoglobin, for vascular endothelial growth factor and for glycolytic enzymes, such as phosphofructokinase, together with mitochondrial and capillary densities, increased in a hypoxia-dependent manner. Functional analyses revealed positive effects on V̇O2max (when measured at altitude) on maximal power output and on lean body mass. In addition to the positive effects of hypoxia training on athletic performance, there is some recent indication that hypoxia training has a positive effect on the risk factors for cardiovascular disease.
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Tài liệu tham khảo
Bailey, D. M., Davies, B. and Baker, J. (2000). Training in hypoxia: modulation of metabolic and cardiovascular risk factors in men. Med. Sci. Sports Exerc.32, 1058–1066.
Bligh, J. and Johnson, K. G. (1973). Glossary of terms for thermal physiology. J. Appl. Physiol.35, 941–961.
Cerretelli, P. and Hoppeler, H. (1996). Morphologic and metabolic response to chronic hypoxia: the muscle system. In Handbook of Physiology , vol. 2, section 4, Environmental Physiology (ed. M. J. Fregly and C. M. Blatteis), pp. 1155–1181. Oxford: Oxford University Press.
Desplanches, D., Hoppeler, H., Linossier, M. T., Denis, C., Claassen, H., Dormois, D., Lacour, J. R. and Geyssant, A. (1993). Effects of training in normobaric hypoxia on human muscle ultrastructure. Pflügers Arch.425, 263–267.
Desplanches, D., Hoppeler, H., Tüscher, L., Mayet, M. H., Spielvogel, H., Ferretti, G., Kayser, B., Leuenberger, M., Grünenfelder, A. and Favier, R. (1996). Muscle tissue adaptation of high-altitude natives to training in chronic hypoxia or acute normoxia. J. Appl. Physiol.81, 1946–1951.
Emonson, D. L., Aminuddin, A. H., Wight, R. L., Scroop, G. C. and Gore, C. J. (1997). Training-induced increases in sea level V̇O2max and endurance are not enhanced by acute hypobaric exposure. Eur. J. Appl. Physiol. 76, 8–12.
Faria, I. E. (1992). Energy expenditure, aerodynamics and medical problems in cycling. Sports Med. 14, 43–63.
Favier, R., Spielvogel, H., Desplanches, D., Ferretti, G., Kayser, B., Lindstedt, S. L. and Hoppeler, H. (1995). Maximal exercise performance in chronic hypoxia and acute normoxia in high-altitude natives. J. Appl. Physiol.78, 1868–1874.
Geiser, J., Vogt, M., Billeter, R., Zuleger, C., Belforti, F. and Hoppeler, H. (2001). Training high – living low: changes of aerobic performance and muscle structure with training at simulated altitude. Int. J. Sports Med. (in press).
Green, H. J., Sutton, J. R., Cymerman, A., Young, P. M. and Houston, C. S. (1989). Operation Everest II: Adaptations in human skeletal muscle. J. Appl. Physiol.66, 2454–2461.
Harms, S. J. and Hickson, R. C. (1983). Skeletal muscle mitochondria and myoglobin, endurance and intensity of training. J. Appl. Physiol. 54, 798–802.
Hickson, R. C. (1981). Skeletal muscle cytochrome c and myoglobin, endurance and frequence of training. J. Appl. Physiol. 51, 746–749.
Hochachka, P. W., Buck, L. T., Doll, C. J. and Land, S. C. (1996). Unifying theory of hypoxia tolerance: Molecular/metabolic defense and rescue mechanisms for surviving oxygen lack. Proc. Natl. Acad. Sci. USA93, 9493–9498.
Hochachka, P. W., Gunga, H. C. and Kirsch, K. (1998). Our ancestral physiological phenotype: An adaptation for hypoxia tolerance and for endurance performance? Proc. Natl. Acad. Sci. USA95, 1915–1920.
Hochachka, P. W. and Somero, G. N. (1984). Biochemical Adaptation. Princeton, NJ: Princeton University Press. 557pp.
Hochachka, P. W., Stanley, C., Merkt, J. and Sumar Kalinowski, J. (1983). Metabolic meaning of elevated levels of oxidative enzymes in high altitude adapted animals: An interpretive hypothesis. Respir. Physiol.52, 303–313.
Hoppeler, H. (1986). Exercise-induced ultrastructural changes in skeletal muscle. Int. J. Sports Med.7, 187–204.
Hoppeler, H., Billeter, R., Horvath, P. J., Leddy, J. J. and Pendergast, D. R. (1999). Muscle structure with low- and high-fat diets in well-trained male runners. Int. J. Sports Med.20, 522–526.
Hoppeler, H., Howald, H., Conley, K., Lindstedt, S. L., Claassen, H., Vock, P. and Weibel, E. R. (1985). Endurance training in humans: Aerobic capacity and structure of skeletal muscle. J. Appl. Physiol.59, 320–327.
Hoppeler, H., Kleinert, E., Schlegel, C., Claassen, H., Howald, H. and Cerretelli, P. (1990). Muscular exercise at high altitude. II. Morphological adaptation of skeletal muscle to chronic hypoxia. Int. J. Sports Med.11, S3–S9.
Howald, H., Pette, D., Simoneau, J. A., Uber, A., Hoppeler, H. and Cerretelli, P. (1990). Muscular exercise at high altitude. III. Effects of chronic hypoxia on muscle enzymes. Int. J. Sports Med.11, S10–S14.
Jacobs, I., Esbjörnsson, M., Sylven, C., Holm, I. and Jansson, E. (1987). Sprint training effects on muscle myoglobin, enzymes, fiber types and blood lactate. Med. Sci. Sports Exerc. 19, 368–374.
Jansson, E., Sylven, C. and Nordevang, E. (1982). Myoglobin in the quadriceps femoris muscle of competitive cyclists and untrained men. Acta Physiol. Scand. 114, 627–629.
Kayser, B., Acheson, K., Décombaz, J., Fern, E. and Cerretelli, P. (1992). Protein absorption and energy digestibility at high altitude. J. Appl. Physiol.73, 2425–2431.
Kayser, B., Hoppeler, H., Claassen, H. and Cerretelli, P. (1991). Muscle structure and performance capacity of Himalayan Sherpas. J. Appl. Physiol.70, 1938–1942.
Kayser, B., Hoppeler, H., Desplanches, D., Marconi, C., Broers, B. and Cerretelli, P. (1996). Muscle ultrastructure and biochemistry of lowland Tibetans. J. Appl. Physiol.81, 419–425.
Kayser, B., Narici, M., Milesi, S., Grassi, B. and Cerretelli, P. (1993). Body composition and maximum alactic anaerobic performance during a one month stay at high altitude. Int. J. Sports Med.14, 244–247.
MacDougall, J. D., Green, H. J., Sutton, J. R., Coates, G., Cymerman, A. Y. P. and Houston, C. S. (1991). Operation Everest-II: Structural adaptations in skeletal muscle in response to extreme simulated altitude. Acta Physiol. Scand.142, 421–427.
Martinelli, M., Winterhalder, R., Cerretelli, P., Howald, H. and Hoppeler, H. (1990). Muscle lipofuscin content and satellite cell volume is increased after high altitude exposure in humans. Experientia46, 672–676.
Masuda, K., Choi, J. Y., Shimojo, H. and Katsuta, S. (1999). Maintenance of myoglobin concentration in human skeletal muscle after heavy resistance training. Eur. J. Appl. Physiol. 79, 347–352.
Melissa, L., MacDougall, J. D., Tarnopolsky, M. A., Cipriano, N. and Green, H. J. (1997). Skeletal muscle adaptations to training under normobaric hypoxic versus normoxic conditions. Med. Sci. Sports Exerc.29, 238–243.
Reynafarje, B. (1962). Myoglobin content and enzymatic activity of muscle and altitude adaptation. J. Appl. Physiol.17, 301–305.
Rosser, B. W. and Hochachka, P. W. (1993). Metabolic capacity of muscle fibers from high-altitude natives. Eur. J. Appl. Physiol.67, 513–517.
Semenza, G. L. (2000). HIF-1: mediator of physiological and pathophysiological responses to hypoxia. J. Appl. Physiol.88, 1474–1480.
Svedenhag, K., Henriksson, J. and Sylven, C. (1983). Dissociation of training effects on skeletal muscle mitochondrial enzymes and myoglobin in man. Acta Physiol. Scand. 117, 213–218.
Terrados, N., Jansson, E., Sylven, C. and Kaijser, L. (1990). Is hypoxia a stimulus for synthesis of oxidative enzymes and myoglobin? J. Appl. Physiol.68, 2369–2372.
Terrados, N., Melichna, J., Sylven, C., Jansson, E. and Kaijser, L. (1988). Effects of training at simulated altitude on performance and muscle metabolic capacity in competitive road cyclists. Eur. J. Appl. Physiol.57, 203–209.
Valdivia, E. (1958). Total capillary bed in striated muscle of Guinea pigs native to the Peruvian mountains. Am. J. Physiol.194, 585–589.
Vogt, M. (1999). Hypoxie und Diät als Beeinflussungsvariablen trainingsbedingter Adaptationsprozesse in der menschlichen Skelettmuskulatur. Dissertation, Philosophisch-Naturwissenschaftliche Fakultät, Universität Bern.
Vogt, M., Puntschart, A., Geiser, J., Zuleger, C., Billeter, R. and Hoppeler, H. (2001). Training high – living low: Molecular adaptations in human skeletal muscle to endurance training under simulated high-altitude conditions. J. Appl. Physiol. 91, 173–182.
Vogt, M., Werlen, L. and Hoppeler, H. (1999). Spielformen des Höhentrainings. Schweiz. Zeitschr. Med. Traumatol.47, 125–128.