West, B., Clark, I. E., Pettit, C. D., Murray, S. R., Kernozek, T. W., & Pettit, R. W. (2013). Applying the critical velocity model for an off-season interval training program. Medicine & Science in Sports & Exercise, 45(5), Supplement abstract number 2151.

This study evaluated female soccer players completing one of two high-intensity interval training regimes: a short group (N = 6) completing a higher velocity and shorter time protocol, and a long group (N = 10) completing a lower velocity, longer time protocol .Groups trained two days per week for four weeks. For each workout, both groups ran at velocities exceeding critical velocity designed to deplete identical fractional percentages (%) of D’, or interval t = [D – (D’ x %)]/critical velocity, where D is the training displacement, and D’ is the velocity-time curvature constant. The metrics of critical velocity and the curvature constant, along with total performance (velocity for 180 seconds) and the velocity at 90 seconds were used as an estimate of the velocity at maximum oxygen uptake (vVO2max) to evaluate pre- and post-training values during a 3-minute all-out exercise test.

Despite differences in velocity-time configurations, both groups increased their critical velocity and decreased their velocity-time curvature constant. The vVO2max for the team (i.e., both groups) increased from pre- to post-training by 0.14 m/second, and V180 seconds increased by 0.11m/second.

Implication. High-intensity interval training bouts that range from two to five minutes are suitable for increasing critical velocity in already-trained female athletes. These bouts are of insufficient intensity to increase the velocity-time curvature constant, indeed they resulted in a decrease in the constant. To increase the velocity-time curvature constant, it is suggested that an examination of high-intensity interval training intensities that are <2 minutes and >130% of vVO2max be used as the task.

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