Tam 2016 Eur J Appl Physiol
|Tam E, Bruseghini P, Calabria E, Sacco LD, Doria C, Grassi B, Pietrangelo T, Pogliaghi S, Reggiani C, Salvadego D, Schena F, Toniolo L, Verratti V, Vernillo G, Capelli C (2016) 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. Eur J Appl Physiol 116:129-44.|
Abstract: We investigated the effects of moderate-intensity training at low and high altitude on VO2 and QaO2 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.
Breath-by-breath VO2 and beat-by-beat QaO2 at the onset of moderate-intensity cycling exercise and energy cost of walking (Cw) 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 VO2 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 QaO2 kinetics and Cw 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 VO2 kinetics at exercise onset.
• Keywords: Exercise training, Aerobic metabolism, Chronic hypoxia, Women, VO2max, Energy cost of walking, Cryopreserved muscle fibers
Labels: MiParea: Respiration, Exercise physiology;nutrition;life style
Organism: Human Tissue;cell: Skeletal muscle Preparation: Permeabilized tissue
Regulation: Coupling efficiency;uncoupling Coupling state: LEAK, OXPHOS Pathway: N, S, NS, ROX HRR: Oxygraph-2k
E Gnaiger (2015-12-08)
- The 'respiratory control ratio' or 'respiratory acceptor control ratio' has been defined as the ratio of State 3/State 4 respiration (Chance and William 1955), analogous to the P/L ratio (Gnaiger 2009). With a decrease of P and and increase of L, the P/L ratio decreases.
- There are statistical arguments to express the coupling control ratio as the inverse of the respiratory acceptor control ratio (Gnaiger 2020). The L/P coupling control ratio has lower and upper limits from 0.0 to 1.0 and increases with an increase of L and a decrease of P.
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