Critical velocity and time spent at a high level of VO2 for short intermittent runs at supramaximal velocities

This study was designed to determine the intermittent critical velocity, the time spent at maximal oxygen uptake ((V)over dot O(2)max) and the time spent above 90% of (V) over dot O(2)max for short intermittent runs of 15 s at supramaximal velocities, alternating with 15 s of passive recovery. Nine male subjects performed 5 field-tests to exhaustion (tlim): 4 intermittent runs at 110%, 120%, 130% and 140% of maximal aerobic speed (MAS) and 1 continuous run at 100% of MAS. Results have shown the mean intermittent critical velocity (4.82 +/- 0.41 m.s(-1)) was not significantly different from MAS (4.63 +/- 0.37 m.s(-1)). Intermittent runs at 110% and 120% of MAS and the continuous run at 100% of MAS lead all subjects to reach (V)over dot O(2)max. However intermittent runs at 120% of MAS (202 +/- 66 s) allowed subjects to spend a significantly longer time at (V)over dot O(2)max (p <.05) than intermittent runs at 110% (116 +/- 42 s), 130% (50 47 s), 140% (48 +/- 59 s) of MAS and continuous run at 100% of MAS (120 +/- 42 s). The time spent between 90 and 100% of (V)over dot O(2)max was significantly longer (p <.05) for intermittent runs at 110% (383 +/- 180 s) and for 120% (323 +/- 272 s) of MAS than for intermittent runs at 130% (135 +/- 133 s), 140% of MAS (77 +/- 96 s) and for continuous run at 100% of MAS (217 +/- 114 s). Consequently, this kind of intermittent exercise with intensities from intermittent critical velocity to 120% of MAS could be introduced in a training program when the purpose is to increase (V)over dot O(2)max.