A hypoxia complement differentiates the muscle response to endurance exercise

Schmutz, Silvia; Däpp, Christoph; Wittwer, Matthias; Durieux, Anne-Cécile; Mueller, Matthias; Weinstein, Felix; Vogt, Michael; Hoppeler, Hans; Flück, Martin (2010). A hypoxia complement differentiates the muscle response to endurance exercise. Experimental physiology, 95(6), pp. 723-35. Oxford: Blackwell 10.1113/expphysiol.2009.051029

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Metabolic stress is believed to constitute an important signal for training-induced adjustments of gene expression and oxidative capacity in skeletal muscle. We hypothesized that the effects of endurance training on expression of muscle-relevant transcripts and ultrastructure would be specifically modified by a hypoxia complement during exercise due to enhanced glycolytic strain. Endurance training of untrained male subjects in conditions of hypoxia increased subsarcolemmal mitochondrial density in the recruited vastus lateralis muscle and power output in hypoxia more than training in normoxia, i.e. 169 versus 91% and 10 versus 6%, respectively, and tended to differentially elevate sarcoplasmic volume density (42 versus 20%, P = 0.07). The hypoxia-specific ultrastructural adjustments with training corresponded to differential regulation of the muscle transcriptome by single and repeated exercise between both oxygenation conditions. Fine-tuning by exercise in hypoxia comprised gene ontologies connected to energy provision by glycolysis and fat metabolism in mitochondria, remodelling of capillaries and the extracellular matrix, and cell cycle regulation, but not fibre structure. In the untrained state, the transcriptome response during the first 24 h of recovery from a single exercise bout correlated positively with changes in arterial oxygen saturation during exercise and negatively with blood lactate. This correspondence was inverted in the trained state. The observations highlight that the expression response of myocellular energy pathways to endurance work is graded with regard to metabolic stress and the training state. The exposed mechanistic relationship implies that the altitude specificity of improvements in aerobic performance with a 'living low-training high' regime has a myocellular basis.

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:	0958-0670
Publisher:	Blackwell
Language:	English
Submitter:	Factscience Import
Date Deposited:	04 Oct 2013 14:09
Last Modified:	05 Dec 2022 14:00
Publisher DOI:	10.1113/expphysiol.2009.051029
PubMed ID:	20176680
Web of Science ID:	000277692000008
URI:	https://boris.unibe.ch/id/eprint/955 (FactScience: 201553)