A physiological description of critical velocity

Although critical velocity (CV) provides a valid index of aerobic function, the physiological significance of CV is not known. Twelve individuals performed exhaustive runs at 95% to 110% of the velocity at which (V) over dot O(2)max was attained in an incremental test. (V) over dot O(2)max was elicited in each run. Using the time to exhaustion at each velocity, CV was calculated for each participant. Using the time to achieve (V) over dot O(2)max at each velocity, which was shorter at higher velocities, a parameter we have designated as CV' was calculated for each participant. During exercise at or below CV', (V) over dot O(2)max cannot be elicited. CV (238 +/- 24 m . min(-1)) and CV' (239 +/- 25 m . min(-1)) were equal (t = 0.60, p = 0.56) and correlated (r = 0.97, p < 0.01). These results demonstrate that CV is the threshold intensity above which exercise of sufficient duration will lead to attainment of (V) over dot O(2)max.