Tolerance to high-intensity intermittent running exercise: do oxygen uptake kinetics really matter?

We examined the respective associations between aerobic fitness ((V) Over dotO(2)max), metabolic control ((V) Over dotO(2) kinetics) and locornotor function, and various physiological responses to high-intensity intermittent (HIT) running exercise in team sport players. Eleven players (30.5 3.6 year) performed a series of tests to determine their (V) Over dotO(2)max and the associated velocity (v(V) Over dotO(2)max), maximal sprinting speed (MSS) and (V) Over dotO(2) kinetics at exercise onset in the moderate and severe intensity domains, and during recovery ((V) Over dotO(2) Toff SEV). Cardiorespiratory variables, oxygenation and electromyography of lower limbs muscles and blood lactate ([La]) concentration were collected during a standardized HIT protocol consisting in 8 sets of 10, 4-s runs. During HIT four players could not complete more than two sets; the others finished at least five sets. Metabolic responses to the two first sets of HIT were negatively correlated with (V) Over dotO(2)max, v(V) Over dotO(2)max, and (V) Over dotO(2)(iota)off SEV (r = 0.6 to 0.8), while there was no clear relationship with the other variables. VO2, oxygenation and [La] responses to the first two sets of HIT were the only variables that differed between the players which could complete at least five sets or those who could not complete more than two sets. Players that managed to run at least five sets presented, in comparison with the others, greater v(V) Over dotO(2)max [ES = +1.5(0.4; 2.7), MSS(ES = +1.0(0.1; 1.9)] and training load [ES = +3.8 (2.8; 4.9)]. There was no clear between-group difference in any of the (V) Over dotO(2) kinetics measures [e.g., ES = 0.1(-1.4; 1.2) for (V) Over dotO(2)(iota)on n SEV]. While (V) Over dotO(2)max and v(V) Over dotO(2)max are likely determinant for HIT tolerance, the importance of (V) Over dotO(2) kinetics as assessed in this study appears limited in the present population. Knowing the main factors influencing tolerance to HIT running exercise may assist practitioners in personalizing training interventions.