Although critical velocity (CV) provides a valid index of aerobic function,
the physiological significance of CV is not known. Twelve individuals perf
ormed 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 elici
ted in each run. Using the time to exhaustion at each velocity, CV was calc
ulated 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 h
ave 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 le
ad to attainment of (V) over dot O(2)max.