Biomechanical Events in the Time to Exhaustion at Maximum Aerobic Speed

Abstract

Recent studies reported good intra-individual reproducibility, but great inter-individual variation in a sample of elite athletes, in time to exhaustion (t lim) at the maximal aerobic speed (MAS: the lowest speed that elicits V̇O 2max in an incremental treadmill test). The purpose of the present study was, on the one hand, to detect modifications of kinematic variables at the end of the t lim of the V̇O 2max test and, on the other hand, to evaluate the possibility that such modifications were factors responsible for the inter-individual variability in t lim. Eleven sub-elite male runners (Age = 24 ± 6 years; V̇O 2max = 69.2 ± 6.8 ml kg –1 min –1; MAS = 19.2 ± 1.45 km h –1; t lim = 301.9 ± 82.7 s) performed two exercise tests on a treadmill (0% slope): an incremental test to determine V̇O 2max and MAS, and an exhaustive constant velocity test to determine t lim at MAS. Statistically significant modifications were noted in several kinematic variables. The maximal angular velocity of knee during flexion was the only variable that was both modified through the t lim test and influenced the exercice duration. A multiple correlation analysis showed that t lim was predicted by the modifications of four variables (R = 0.995, P < 0.01). These variables are directly or indirectly in relation with the energic cost of running. It was concluded that runners who demonstrated stable running styles were able to run longer during MAS test because of optimal motor efficiency.