Freese, E. C., Gist, N. H., & Cureton, K. J. (2012). Physiological responses to an acute bout of sprint interval cycling. Presentation 2203 at the 59th Annual Meeting of the American College of Sports Medicine, San Francisco, California; May 29-June 2, 2012.

This study determined the oxygen uptake and related cardiorespiratory responses and associated energy expenditure during an acute bout of sprint interval cycling in college students (M = 6; F = 6). Ss completed two sprint interval cycling sessions with at least seven days between trials. Sprint interval cycling was performed on a mechanically braked cycle ergometer and involved a 5-minute warm-up followed by four 30-second all-out sprints with four minutes active recovery. Work performed was quantified using an optical sensor to measure flywheel revolutions. Oxygen uptake was measured continuously by open-circuit spirometry during the last minute of warm-up and throughout the sprint interval cycling session. Energy expenditure during each sprint was based on the estimated anaerobic energy contribution to the sprints and the net aerobic energy calculated from measured oxygen uptake above rest.

Average work performed decreased during the four sprints for both genders. Percent fatigue increased from sprint 1 to sprint 4. Average aerobic, anaerobic, and total energy expended during the 18 minutes necessary to complete the sprint interval cycling sessions were higher for males than females. Peak oxygen uptake, peak heart rate, and peak minute ventilation increased with each sprint except sprint 4 which produced values lower than sprint 3.

Implication. An acute bout of sprint interval cycling elicits submaximal oxygen uptake and cardiorespiratory responses during each interval that approximates 80% of estimated maximal values. The energy expended is much lower than that expended in moderate intensity aerobic exercise training programs shown to improve aerobic capacity and insulin sensitivity. High-intensity sprint interval cycling reduced postprandial triglycerides, signifying the importance of this form of exercise.

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