Tucker, W. J., Malone, K., Sawyer, B. J., Bhammar, D. M., & Gaesser, G. A. (2013). Comparison of physiological responses to two high-intensity interval exercise protocols. Medicine & Science in Sports & Exercise, 45(5), Supplement abstract number 2809.

This study compared two high-intensity interval exercise protocols with regard to oxygen uptake, heart rate, power output, blood lactate concentration, and rating of perceived exertion. Active males (N = 7) performed in random order on separate days the following high-intensity interval exercise protocols on a cycle ergometer: 1) 16 x 1: 16 one-minute intervals at 85-90% HRmax separated by one-minute periods of active recovery, and 2) 4 x 4: four four-minute intervals at 85-90% HRmax separated by three-minute periods of active recovery. Power output was adjusted during each interval to elicit 85-90% HRmax. Oxygen uptake and heart rate were recorded continuously, rating of perceived exertion (10-point scale) was recorded each minute, and blood lactate concentration was measured three times (pre-, mid-, and post-exercise).

Mean heart rate during the high-intensity interval periods, mean heart rate during the entire high-intensity interval exercise protocols, mean rating of perceived exertion, mid-exercise session blood lactate concentration, and post-exercise blood lactate concentration were not different between the two protocols. However, during the high-intensity interval periods of each protocol, power output was significantly greater for the 16 x 1 protocol. Although mean oxygen uptake during the entire exercise was the same for both protocols, this was achieved with a higher oxygen uptake during the high-intensity interval periods and lower oxygen uptake during the active recovery periods for the 4 x 4 protocol.

Implication. The two high-intensity interval exercise protocols elicited similar heart rate, blood lactate concentration, and rating of perceived exertion responses despite significantly higher power output maintained during the high-intensity periods of the 16 x 1 protocol and significantly higher oxygen uptake reached during high-intensity periods of the 4 x 4 protocol.

Short work and rest periods (one minute each) at an intensity of 85-90 maximum heart rate produce greater power output than in longer work and rest periods (four and three minutes respectively). In activities where high power outputs are required (e.g., swimming, kayaking), short work-rest periods are preferable for training than longer work-rest periods.

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