BIOMECHANICAL EVENTS IN THE TIME TO EXHAUSTION AT MAXIMUM AEROBIC SPEED

Recent studies reported good intra-individual reproducibility, but gre at inter-individual variation in a sample of elite athletes, in time t o exhaustion (t(lim)) at the maximal aerobic speed (MAS: the lowest sp eed that elicits (V) over dot O-2max in an incremental treadmill test) . The purpose of the present study was, on the one hand, to detect mod ifications of kinematic variables at the end of the t(lim) of the (V) over dot O-2max test and, on the other hand, to evaluate the possibili ty that such modifications were factors responsible for the inter-indi vidual variability in t(lim). Eleven sub-elite male runners (Age = 24 +/- 6 years; (V) over dot O-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 ex ercise rests on a treadmill (0% slope): an incremental test to determi ne (V) over dot O-2max and MAS, and an exhaustive constant velocity te st to determine t(lim) at MAS. Statistically significant modifications were noted in several kinematic variables. The maximal angular veloci ty of knee during flexion was the only variable that was both modified through the t(lim) test and influenced the exercice duration. A multi ple correlation analysis showed that t(lim) was predicted by the modif ications of four variables (R = 0.995, P < 0.01). These variables are directly or indirectly in relation with the energic cost of running. I t was concluded that runners who demonstrated stable running styles we re able to run longer during MAS test because of optimal motor efficie ncy.