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Skeletal muscle changes after endurance training at high altitude
A X Bigard1, A Brunet, C Y Guezennec
1Division de Physiologie Métabolique et Hormonale, Centre d'Etudes et de Recherches de Médecine Aérospatiale, Brétigny, France.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|December 1, 1991
Summary
Endurance training at high altitude enhances skeletal muscle adaptations, increasing specific fiber types and metabolic enzyme activity. These changes suggest improved muscle function under hypoxic conditions.
Area of Science:
- Exercise Physiology
- Altitude Training
- Skeletal Muscle Biology
Background:
- Endurance training impacts skeletal muscle adaptations.
- High altitude environments present unique physiological challenges.
Purpose of the Study:
- To investigate the effects of endurance training on rat skeletal muscle at sea level versus simulated high altitude.
- To identify specific muscle fiber type and metabolic enzyme adaptations induced by high-altitude training.
Main Methods:
- Male Wistar rats were divided into four groups: sea level exercise, high altitude exercise, sea level sedentary, and high altitude sedentary.
- Training involved 14 weeks of swimming. Body weight and muscle mass were recorded.
- Muscle fiber type percentages and enzyme activities (citrate synthase, HAD, hexokinase, lactate dehydrogenase) were analyzed.
Main Results:
- High-altitude training increased the percentage of type IIa and IIab fibers in fast-twitch muscles (EDL, plantaris).
- Metabolic enzyme activity (citrate synthase, HAD) significantly increased, particularly at high altitude.
- Hexokinase activity increased, while lactate dehydrogenase activity decreased with high-altitude training.
Conclusions:
- Endurance training at high altitude induces distinct skeletal muscle adaptations compared to sea level training.
- These adaptations include shifts in muscle fiber type composition and enhanced metabolic enzyme function, potentially improving performance in hypoxic conditions.