Critical velocity of continuous and intermittent running exercise

Abstract

The relationship between exhaustion time (t_lim) and distance D_lim for running exercises at constant velocity until exhaustion can be described by a linear relationship (D_lim = a + b t_lim) whose slope corresponds to a critical velocity. Seven runners participated to the study which compared the critical velocity of continuous versus intermittent running exercises. The critical velocity for continuous running (V_critc) was calculated from the results (t_limc and D_limc) of running exercises performed at 95 and 105 % of the final velocity of the Montreal Track Test (vMTT). The intermittent running consisted of repetitions of running exercises performed at 95 and 105 % vMTT during a time equal to half the value of the corresponding t_limc, The subjects recovered during a time equal to running time while jogging at a slow pace. The critical velocity for intermittent running (V_criti) was calculated from the cumulated running distance (D_limi) and cumulated running time (t_limi) corresponding to 95 and 105 % vMTT. V_criti was equal to V_critc (4.56 ± 0.444 m.s⁻¹ vs 4.60 ± 0.416 m.s⁻¹). Nevertheless, in some subjects, the repetition numbers were very different for the intermittent running exercises at 95 and 105 % vMTT. This paradoxical result could be explained by the fact that the value of V_crit should be theoretically little sensitive to a large error in the value of t_lim corresponding to a velocity slightly higher than critical velocity, for intermittent exercises as well as continuous exercises.