Purpose: This study aimed to determine the relationships between training-induced changes in the variable values of the power-duration relationship (CP and W') and those of pulmonary oxygen uptake (V̇O 2 ) kinetics (the fundamental phase time constant; τVO2, and the slow component amplitude; V̇O 2sc ). Methods: Eleven healthy untrained males underwent 2 weeks of severe-intensity exercise training. Before and after training, V̇O 2max was assessed via an incremental exercise test on a cycle ergometer, CP and W' were assessed via constant power determination trials, and V̇O 2 kinetics were assessed during exercise at a PO 10% above CP (post-training at the same absolute and relative intensity as pre-training). A previously described and validated computer model of the human skeletal muscle bioenergetic system was used to provide further insight into training-induced changes. Results: CP and τVO2were strongly inversely correlated before and after training, and their training-induced changes were also correlated. Computer simulations suggested that increased oxidative phosphorylation activity (k OX ) was the main factor determining the training-induced changes in CP and τVO2. Exercise training increased W' and reduced the amplitude of the V̇O 2sc , however, the training-induced changes in W' and the V̇O 2sc were not correlated. Model simulations suggested that variations in k OX , the accessible phosphate (+creatine) pool (P acc ), and the peak inorganic phosphate (P i ) concentrations attained prior to task failure (Pi peak ) could explain the observed training-induced alterations in W' and the V̇O 2sc . Conclusions: The present study suggests that the bioenergetic mechanisms underpinning CP and τVO2are similar, whereas the relationship between W' and the V̇O 2sc appears somewhat more complex.
Lei et al. (Tue,) studied this question.