Extraordinary Claims in the Literature on High-Intensity Interval Training: II. Are the Extraordinary Claims Supported by Extraordinary Evidence?

Dishman challenged kinesiologists to seek a compromise between “the ideal physiological prescription and a manageable behavioral prescription.” High-intensity interval training (HIIT) is the first exercise modality that has been claimed to meet this challenge, combining substantial benefits for fitness and health with pleasure and enjoyment. If true, these claims may revolutionize the science and practice of exercise. In this paper, four claims are critically appraised: (a) HIIT lowers the risk of mortality more than moderate-intensity continuous exercise, (b) HIIT doubles endurance performance after only 15 min of training over 2 weeks, (c) 1 min of HIIT is equivalent to 45 min of moderate-intensity continuous exercise, and (d) HIIT is more pleasant and enjoyable than moderate-intensity continuous exercise. The evidence for these claims appears questionable. Kinesiology should heed the principle endorsed by Hume, Laplace, and Sagan, namely that extraordinary claims should be supported by commensurate evidence.