Jacobs 2013 Abstract MiP2013
|Jacobs R, Flück D, Bonne TC, Bürgi S, Christensen PM, Toigo M, Lundby C (2013) Improvements in exercise performance with high-intensity interval training are facilitated by an increase in skeletal muscle mitochondria content. Mitochondr Physiol Network 18.08.|
Six sessions of high-intensity interval training (HIT) completed over a two-week span is sufficient to improve exercise capacity [1,2]. The mechanisms explaining such improvements are not fully understood. Accordingly, the aim of the present study was to perform a comprehensive evaluation of physiologically relevant adaptations occurring after 6 sessions of HIT in sedentary young adults and determine the mechanisms explaining improvements in exercise performance. Sixteen sedentary subjects completed 6 sessions of repeated [8-12] 60 s intervals of high-intensity cycling (100% peak power output elicited during incremental maximal exercise test) intermixed with 90 s of recovery cycling at a low intensity (30 W) over a 2-week period. Potential training-induced alterations in skeletal muscle respiratory capacity, mitochondrial content, skeletal muscle oxygenation, cardiac capacity, blood volumes, and peripheral fatigue resistance were assessed. Training improved maximal oxygen consumption (VO2max; ~8%; p=0.026) and cycling time to complete a set amount of work (~5%; p=0.008). Skeletal muscle respiratory capacity improved, most likely as a result of an increased content of skeletal muscle mitochondria (~20%, p=0.026). Maximal tissue oxygenation improved by 10% while maximal cardiac output, blood volumes, oxygen carrying capacity, and relative measures of peripheral fatigue resistance were all unaltered with training. These results suggest that acute increases in mitochondrial content following two-weeks of HIT may facilitate improvements in respiratory capacity, tissue oxygenation, and ultimately are responsible for the improvements in both maximal whole-body exercise capacity as well as endurance performance in previously sedentary individuals.
Labels: MiParea: Respiration, mt-Biogenesis;mt-density, Exercise physiology;nutrition;life style
Organism: Human Tissue;cell: Skeletal muscle Preparation: Intact organism, Permeabilized tissue
Regulation: Oxygen kinetics Coupling state: OXPHOS
1 - Zurich Center for Integrative Human Physiology (ZIHP);
2 - Institute of Physiology, University of Zurich, Switzerland;
3 - Department of Exercise and Sport Sciences, University of Copenhagen, Denmark;
4 - Exercise Physiology, Institute of Human Movement Sciences, ETH Zurich, Switzerland.
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