Abstract
The purpose of this study was to determine the utility of high-intensity interval training (HIIT) as a practical strategy for promoting exercise adherence in comparison with traditional moderate-intensity continuous exercise (MICT). Inactive individuals with prediabetes (Mage = 51±10) were randomly assigned to HIIT (n = 10) or MICT (n = 16) involving 7 days of supervised training and 3 home sessions over a 2-week period. Exercise sessions for each condition were progressive in nature and matched for external work. Following the program, participants were instructed to maintain HIIT or MICT three days per week independently for one month. Exercise adherence was measured subjectively using training logs by calculating percentage adherence and objectively using accelerometers worn at baseline and one-month follow-up. Time spent in moderate and vigorous activity was calculated. Participants engaging in HIIT self-reported significantly greater adherence when compared to MICT t(18.96) = 2.08, p = .05, d = 0.75. Accelerometer analyses revealed no statistical difference between conditions in total time spent in moderate activity at baseline or one-month follow-up (p > .05). However, there was a significant difference between the number of minutes spent in vigorous activity between conditions at one-month follow-up, F(1, 20) = 4.41, p = .049, d = 0.92, with individuals engaging in HIIT engaging in more minutes of vigorous exercise than those in MICT. This feasibility study is the first to examine adherence to HIIT outside of a supervised laboratory setting and demonstrates that individuals with prediabetes can adhere to HIIT independently for one month following a very brief intervention. Adherence to HIIT, as assessed by self-report, was greater than standard care MICT. The greater amount of vigorous activity performed within the HIIT condition has potential clinical importance given the additional benefits of vigorous intensity physical activity over moderate physical activity for reducing cardiometabolic risk.
