Key result
Endurance cycling training for 20 weeks shortened τp of pulmonary V̇O2 on-kinetics during moderate-intensity cycling from 28.3 to 23.0 s (P=0.005).
Why the study?
Does endurance cycling training improve pulmonary V̇O2 kinetics in untrained physically active men?
Does endurance cycling training improve pulmonary V̇O2 kinetics in untrained physically active men?
Absolute Event Rate: 23% vs 28.3%
p-value: p=0.005
Prolonged endurance training accelerates pulmonary V̇O2 on-kinetics, which modeling suggests is primarily driven by an increase in each-step parallel activation of oxidative phosphorylation.
Associated with faster VO2 on-kinetics in active men; hypothesis-generating for mechanisms and clinical relevance.
The effect of prolonged endurance training on the pulmonary V̇O2 on- and off-kinetics in humans, in relation to muscle mitochondria biogenesis, is investigated. Eleven untrained physically active men (means±SD: age 22.4±1.5 years, V̇O2peak 3,187±479 ml/min) performed endurance cycling training (4 sessions per week) lasting 20 wk. Training shortened τp of the pulmonary V̇O2 on-kinetics during moderate-intensity cycling by ∼19% from 28.3±5.2 to 23.0±4.0 s (P=0.005). τp of the pulmonary V̇O2 off-kinetics decreased by ∼11% from 33.7±7.2 to 30.0±6.6 (P=0.02). Training increased (in vastus lateralis muscle) mitochondrial DNA copy number in relation to nuclear DNA (mtDNA/nDNA) (+53%) (P=0.014), maximal citrate synthase (CS) activity (+38%), and CS protein content (+38%) (P=0.004), whereas maximal cytochrome c oxidase (COX) activity after training tended to be only slightly (+5%) elevated (P=0.08). By applying to the experimental data, our computer model of oxidative phosphorylation (OXPHOS) and using metabolic control analysis, we argue that COX activity is a much better measure of OXPHOS intensity than CS activity. According to the model, in the present study a training-induced increase in OXPHOS activity accounted for about 0-10% of the decrease in τp of muscle and pulmonary V̇O2 for the on-transient, whereas the remaining 90-100% is caused by an increase in each-step parallel activation of OXPHOS.
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Żołądź et al. (2014) studied Untrained physically active men (n=11). Endurance cycling training was evaluated on τp of the pulmonary V̇O2 on-kinetics during moderate-intensity cycling (p=0.005). Endurance cycling training for 20 weeks shortened τp of pulmonary V̇O2 on-kinetics during moderate-intensity cycling from 28.3 to 23.0 s (P=0.005).
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