Exercise training in normobaric hypoxia in endurance runners. II. Improvement of mitochondrial properties in skeletal muscle

Ponsot, Elodie; Dufour, Stéphane P; Zoll, Joffrey; Doutrelau, Stéphane; N'Guessan, Benoit; Geny, Bernard; Hoppeler, Hans; Lampert, Eliane; Mettauer, Bertrand; Ventura-Clapier, Renée; Richard, Ruddy (2006). Exercise training in normobaric hypoxia in endurance runners. II. Improvement of mitochondrial properties in skeletal muscle. Journal of applied physiology, 100(4), pp. 1249-57. Bethesda, Md.: American Physiological Society 10.1152/jaaplphysiol.00361.2005

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This study investigates whether adaptations of mitochondrial function accompany the improvement of endurance performance capacity observed in well-trained athletes after an intermittent hypoxic training program. Fifteen endurance-trained athletes performed two weekly training sessions on treadmill at the velocity associated with the second ventilatory threshold (VT2) with inspired O2 fraction = 14.5% [hypoxic group (Hyp), n = 8] or with inspired O2 fraction = 21% [normoxic group (Nor), n = 7], integrated into their usual training, for 6 wk. Before and after training, oxygen uptake (VO2) and speed at VT2, maximal VO2 (VO2 max), and time to exhaustion at velocity of VO2 max (minimal speed associated with VO2 max) were measured, and muscle biopsies of vastus lateralis were harvested. Muscle oxidative capacities and sensitivity of mitochondrial respiration to ADP (Km) were evaluated on permeabilized muscle fibers. Time to exhaustion, VO2 at VT2, and VO2 max were significantly improved in Hyp (+42, +8, and +5%, respectively) but not in Nor. No increase in muscle oxidative capacity was obtained with either training protocol. However, mitochondrial regulation shifted to a more oxidative profile in Hyp only as shown by the increased Km for ADP (Nor: before 476 +/- 63, after 524 +/- 62 microM, not significant; Hyp: before 441 +/- 59, after 694 +/- 51 microM, P < 0.05). Thus including hypoxia sessions into the usual training of athletes qualitatively ameliorates mitochondrial function by increasing the respiratory control by creatine, providing a tighter integration between ATP demand and supply.

Item Type:	Journal Article (Original Article)
Division/Institute:	04 Faculty of Medicine > Pre-clinic Human Medicine > Institute of Anatomy
UniBE Contributor:	Hoppeler, Hans-Heinrich
ISSN:	8750-7587
ISBN:	16339351
Publisher:	American Physiological Society
Language:	English
Submitter:	Factscience Import
Date Deposited:	04 Oct 2013 14:49
Last Modified:	05 Dec 2022 14:15
Publisher DOI:	10.1152/jaaplphysiol.00361.2005
PubMed ID:	16339351
Web of Science ID:	000236854500024
URI:	https://boris.unibe.ch/id/eprint/20360 (FactScience: 3648)