Perceptual responses in free vs. constant pace exercise

The purpose of the present investigation was to study the influence of free versus constant pace on perceived exertion (RPE) and estimated time Limit (ETL). Ten athletes performed a graded test aimed to determine maximal oxygen uptake (VO2max) and the velocity associated with VO2max (vVO2max), a constant run to exhaustion at 90 % vVO2max to determine the time and distance to exhaustion at this relative velocity, a free paced run over the distance to exhaustion set by the time to exhaustion at 90 % vVO2max. Oxygen uptake and velocity during constant pace and free pace runs were both averaged throughout the entire period of exercise and without the last lap. The results did not show any significant effect of free versus constant pace on RPE and ETL. Averaged oxygen uptake between free and constant pace runs was not significantly different, whereas averaged vVO2max, % vVO2max and time to exhaustion was significantly higher for free pace runs only for the entire exercise. Consequently, compared to the constant pace run, the free pace one only allowed athletes to finish the run by a sprint which was effective in increasing performance, but not to perceive the free pacing run as being less strenuous than the constant pace one.