Gokyo Khumbu/Ama Dablam Trek 2012: effects of physical training and high-altitude exposure on oxidative metabolism, muscle composition, and metabolic cost of walking in women

• Published in: European journal of applied physiology 2016-01, Vol.116 (1), p.129-144
• Main Authors: Tam, E., Bruseghini, P., Calabria, E., Sacco, L. Dal, Doria, C., Grassi, B., Pietrangelo, T., Pogliaghi, S., Reggiani, C., Salvadego, D., Schena, F., Toniolo, L., Verratti, V., Vernillo, G., Capelli, Carlo
• Format: Article
• Language: English
• Subjects: Adenosine; Adult; Altitude; Biomedical and Life Sciences; Biomedicine; Blood; Exercise; Female; Human Physiology; Humans; Hypoxia; Metabolism; Middle Aged; Muscle, Skeletal - metabolism; Myosin Heavy Chains - metabolism; Occupational Medicine/Industrial Medicine; Original Article; Oxygen - metabolism; Oxygen Consumption - physiology; Physical Endurance - physiology; Physical fitness; Quadriceps Muscle - metabolism; Sports Medicine; Walking
• ISSN: 1439-6319; 1439-6327
• DOI: 10.1007/s00421-015-3256-z

Purpose We investigated the effects of moderate-intensity training at low and high altitude on V ˙ O 2 and Q ˙ a O 2 kinetics and on myosin heavy-chain expression (MyHC) in seven women (36.3 yy ± 7.1; 65.8 kg ± 11.7; 165 cm ± 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. Methods Breath-by-breath V ˙ O 2 and beat-by-beat Q ˙ a O 2 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. Results Mean response time of V ˙ 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 Q ˙ a O 2 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). Conclusions Although training did not significantly modify muscle phenotype, it induced beneficial adaptations of the oxygen transport–utilization systems witnessed by faster V ˙ O 2 kinetics at exercise onset.