Abstract
We investigated the effects of moderate-intensity training at low and high altitude on O-2 and kinetics and on myosin heavy-chain expression (MyHC) in seven women (36.3 yy +/- A 7.1; 65.8 kg +/- A 11.7; 165 cm +/- A 8) who participated in two 12- to 14-day trekking expeditions at low (598 m) and high altitude (4132 m) separated by 4 months of recovery.Breath-by-breath O-2 and beat-by-beat at the onset of moderate-intensity cycling exercise and energy cost of walking (C (w)) were assessed before and after trekking. MyHC expression of vastus lateralis was evaluated before and after low-altitude and after high-altitude trekking; muscle fiber high-resolution respirography was performed at the beginning of the study and after high-altitude trekking.Mean response time of O-2 kinetics was faster (P = 0.002 and P = 0.001) and oxygen deficit was smaller (P = 0.001 and P = 0.0004) after low- and high-altitude trekking, whereas kinetics and C (w) did not change. Percentages of slow and fast isoforms of MyHC and mitochondrial mass were not affected by low- and high-altitude training. After training altitude, muscle fiber ADP-stimulated mitochondrial respiration was decreased as compared with the control condition (P = 0.016), whereas leak respiration was increased (P = 0.031), leading to a significant increase in the respiratory control ratio (P = 0.016).Although training did not significantly modify muscle phenotype, it induced beneficial adaptations of the oxygen transport-utilization systems witnessed by faster O-2 kinetics at exercise onset.
Lingua originale | English |
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pagine (da-a) | 129-144 |
Numero di pagine | 16 |
Rivista | European Journal of Applied Physiology |
Volume | 116 |
DOI | |
Stato di pubblicazione | Pubblicato - 2016 |
Keywords
- Adult
- Aerobic metabolism
- Altitude
- Chronic hypoxia
- Energy cost of walking
- Exercise training
- Female
- Humans
- Middle Aged
- Muscle, Skeletal
- Myosin Heavy Chains
- Oxygen
- Oxygen Consumption
- Physical Endurance
- Quadriceps Muscle
- Walking
- Women