THE EFFECT OF INTERVAL DURATION DURING INTERMITTENT EXERCISE ON SUBSEQUENT SPRINT PERFORMANCE

Abstract

Different interval durations during acute intermittent exercise can affect the metabolic status within the working muscles. This study compared the effects of the interval duration during intermittent exercise on a subsequent sprint performance and was ethically approved prior to commencing. Nine male subjects (age 20.9 ± 1.1 years, height 179.8 ± 7.4 cm, and body mass 84.2 ± 9.5 kg) completed three 20 minute intermittent exercise protocols on an electronically braked cycle ergometer. Each protocol utilised a work:rest ratio of 1:1 and were completed on separate days. The work periods were performed at an intensity of 75% power achieved at VO2 max with passive rest periods. The interval durations were set at a work:rest of 15:15s, 30:30s and 60:60s which were completed in random order. This work:rest ratio produced the same total amount of work between protocols and isolated the interval durations as the only independent variable. A 15s Wingate anaerobic test (WAnT) was performed subsequent to each intermittent exercise protocol and a WAnT from rest was also completed as a baseline measure. Heart rate and oxygen consumption were recorded throughout each exercise protocol. The WAnTs performed subsequent to the intermittent protocols (15s, 30s and 60s) produced a significantly lower peak power output than the baseline WAnT (P = 0.049, 0.014 and 0.006, respectively). The 60s produced a significantly lower mean power output than the baseline WAnT (P = 0.04). The 60s peak heart rate during the 20 minute exercise protocol was significantly higher than 15s and 30s (P = 0.01 and 0.000, respectively). In conclusion, intermittent exercise causes a significant decrement in sprint peak power output when compared with a baseline measure. The cause of this could be due to a depletion of phosphocreatine within the muscles caused by intermittent exercise.