Abstract.
The adaptation of muscle oxidative function to 6 weeks of endurance cycle training was investigated in eight untrained subjects. Peak oxygen consumption (\(\dot VO_{2peak}\) ) increased by 24% (2.69±0.21 versus 3.34±0.30 l O2 min–1, mean ±SEM, P<0.01) and lactate threshold intensity increased by 53% (121±13 versus 185±15 W, P<0.01) following the training period. Muscle biopsy samples were taken from vastus lateralis before and after training, and respiration in permeabilized muscle fibres was measured. Following training, non-ADP-stimulated respiration (\(\dot V_o\) ) of skinned fibres increased by 35% (0.17±0.01 versus 0.23±0.01 mmol O2·min–1·kg–1 wet weight, P<0.05) and maximal ADP-stimulated respiration (\(\dot V_{\max }\) ) increased by 38% (1.17±0.07 versus 1.62±0.14 mmol O2·min–1·kg–1 wet weight, P<0.05). ADP sensitivity [i.e. the ratio between mitochondrial respiration (after correction for \(\dot V_o\) ) at 0.1 mM ADP and \(\dot V_{\max }\) ] was reduced after training (0.40±0.05 versus 0.26±0.02; P<0.05). Mitochondrial resistance to oxidative stress was investigated by exposing skinned fibres to exogenous reactive oxygen species (ROS). ADP-stimulated respiration was reduced after ROS exposure and the relative decrease was similar before and after training. It is concluded that after endurance training: (1) the relative increase in maximal muscle fibre respiration exceeds that of whole-body oxygen uptake; (2) the sensitivity of mitochondrial respiration to ADP decreases; and (3) the impairment of oxidative function in skinned muscle fibres by ROS remains unchanged.
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Received after revision: 7 December 2000
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Walsh, B., Tonkonogi, M. & Sahlin, K. Effect of endurance training on oxidative and antioxidative function in human permeabilized muscle fibres. Pflügers Arch - Eur J Physiol 442, 420–425 (2001). https://doi.org/10.1007/s004240100538
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DOI: https://doi.org/10.1007/s004240100538