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

Abstract

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 O₂ uptake $(\dot{V}{\text{O}}_{{ 2 {\text{p}}}} {\text{max)}}$, on- and off- $\dot{V}{\text{O}}_{{ 2 {\text{p}}}}$ 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. $\dot{V}{\text{O}}_{{ 2 {\text{p}}}}$ kinetics at Mod onset ($\dot{V}{\text{O}}_{{ 2 {\text{p}}}} \tau_{\text{on}}$) and cessation ($\dot{V}{\text{O}}_{{ 2 {\text{p}}}} \tau_{\text{off}}$) 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 $\dot{V}{\text{O}}_{{ 2 {\text{p}}}} { \max }$ (t > 90% $\dot{V}{\text{O}}_{{ 2 {\text{p}}}} { \max }$) and Reoxy rate after each sprint were also recorded. Despite a low mean $\dot{V}{\text{O}}_{{ 2 {\text{p}}}}$ (48.0 ± 4.1% of $\dot{V}{\text{O}}_{{ 2 {\text{p}}}} { \max }$), SIT performance was associated with high peak $\dot{V}{\text{O}}_{{ 2 {\text{p}}}}$ (90.4 ± 2.8% of $\dot{V}{\text{O}}_{{ 2 {\text{p}}}} { \max }$), 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 < 0.001 for both). Except for t > 90% $\dot{V}{\text{O}}_{{ 2 {\text{p}}}} { \max }$ versus $\dot{V}{\text{O}}_{{ 2 {\text{p}}}} \tau_{\text{off}}$ [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. $\dot{V}{\text{O}}_{{ 2 {\text{p}}}} \tau_{\text{off}}$: r = −0.41 (−0.78; 0.18); P = 0.24]. Present results show that SIT elicits a greater muscle O₂ 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.