Comparison Of Oxygen Consumption In 4-second Sprint Interval Exercise With Varied Intensity And Rest Period

Sprint interval training (SIT) is usually performed at maximal ‘all-out’ intensities, that are 5-8-times higher than the power needed to elicit VO2peak. However, the %VO2peak associated with repeated submaximal power sprints (%Pmax), particularly when paired with varying rest periods, remains unknown. Investigating the %VO2peak in repeated submaximal power sprints is pivotal, enabling the personalization of workout routines to specific training goals. PURPOSE: The aim of this study was to systematically investigate the acute physiological responses induced by three levels of %Pmax intensities (50%, 75%, and 100% of Pmax) with three varying rest periods (15, 30, and 45-s) between thirty 4-s sprints. METHODS: Nine healthy (25 ± 4.9 yrs), recreationally active participants took part in nine trials, performing thirty 4-s sprints during cycling with inertial loading at three different intensities and rest periods, in randomized order. RESULTS: Power outputs varied across differing intensities and rest periods. At 52 ± 0.7 %Pmax and 74% ± 0.3 %Pmax, the average output was constant within the rest periods. However, the ‘all-out’ efforts revealed that 15-s rest elicited a lower (p < 0.05) %Pmax of 88 ± 9.0 %Pmax compared to 95 ± 3.9%, and 96 ± 5.7% of Pmax for 15 vs. 30, and 45-s of rest (p < 0.05). VO2 varied (p < 0.05) across all rest periods: 48 ± 11.3%, 66 ± 13.2%, 84 ± 13.5% of VO2peak for 15-s rest; 35 ± 5.8%, 45 ± 10.5%, 66 ± 12.2% VO2peak for 30-s rest; and 28 ± 6.7%, 33 ± 5.7%, 54 ± 9.8% VO2peak for 45-s rest, corresponding to intensities at 52%, 74%, and 88% of Pmax, respectively. Notably, a linear regression model identified the equation for VO2 (mL/min) = 1088.89 + 28.32(%Pmax intensity) - 38.75(rest in s) (R2 = 0.91). CONCLUSION: A wide range of VO2 responses (i.e., 28-84% VO2peak) can systematically be elicited by varying the intensity and rest period during repeated 4-s sprints cycling using inertial loading, offering valuable insights for designing personalized training regimens.