Performance and physiological responses during a sprint interval training session: relationships with muscle oxygenation and pulmonary oxygen uptake kinetics

The purpose of this study was to examine the cardiorespiratory and muscle oxygenation responses to a sprint interval training (SIT) session, and to assess their relationships with maximal pulmonary O 2 uptake , on- and off- kinetics and muscle reoxygenation rate (Reoxy rate). Ten male cyclists performed two 6-min moderate-intensity exercises (≈90–95% of lactate threshold power output, Mod), followed 10 min later by a SIT session consisting of 6 × 30-s all out cycling sprints interspersed with 2 min of passive recovery. kinetics at Mod onset ( ) and cessation ( ) were calculated. Cardiorespiratory variables, blood lactate ([La] b ) and muscle oxygenation level of the vastus lateralis (tissue oxygenation index, TOI) were recorded during SIT. Percentage of the decline in power output (%Dec), time spent above 90% of ( t > 90% ) and Reoxy rate after each sprint were also recorded. Despite a low mean (48.0 ± 4.1% of ), SIT performance was associated with high peak (90.4 ± 2.8% of ), muscle deoxygenation (sprint ΔTOI = −27%) and [La] b (15.3 ± 0.7 mmol l −1 ) levels. Muscle deoxygenation and Reoxy rate increased throughout sprint repetitions ( P 90% versus [ r = 0.68 (90% CL, 0.20; 0.90); P = 0.03], there were no significant correlations between any index of aerobic function and either SIT performance or physiological responses [e.g., %Dec vs. : r = −0.41 (−0.78; 0.18); P = 0.24]. Present results show that SIT elicits a greater muscle O 2 extraction with successive sprint repetitions, despite the decrease in external power production (%Dec = 21%). Further, our findings obtained in a small and homogenous group indicate that performance and physiological responses to SIT are only slightly influenced by aerobic fitness level in this population.