Does exercise intensity affect Phase II .VO2 kinetics in trained and untrained subjects?
The slowing of phase II VO2 kinetics at higher power outputs within the moderate exercise intensity domain suggests factors like motor unit recruitment, rather than O2 availability, are responsible.
Phase II .VO2 kinetics became progressively slower at higher power outputs in both trained and untrained subjects. That a greater tau1 was evident at a higher power output within the moderate exercise intensity domain (<GET), where O2 availability is presumed not to be limiting, indicates that the slowing of the phase II .VO2 kinetics may be attributed to other factors besides O2 availability such as the recruitment of higher threshold motor units.
Koppo et al. (Sun,) studied this question.
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