Does Exercise Choice Matter For Cardiorespiratory Fitness Improvements?

Abstract

Low cardiorespiratory fitness (CRF) is an important risk factor for cardiometabolic disease and individuals with prediabetes tend to have low CRF. Trials that have compared High-Intensity Interval Training(HIIT) to Moderate-Intensity Continuous Training(MICT) by imposingindividuals to HIIT or MICT haveestablished that HIIT is effective for improving CRF. However, to maintain these improvements, individuals need to adhere to HIIT. Self-determination theory states that providingchoicehas a positive impact on exercise adherence. PURPOSE:To address whether having the choice to engage in HIITor MICT for 6-months (CHOICE) leads to greater changes in CRF (absolute and relative VO2peak) at 6-months when compared to IMposed HIIT (IM-HIIT)or IMposed MICT (IM-MICT) in adults with prediabetes. METHODS: In this single-site randomized trial, 68 low-active adults (56.8±6.6 yrs, mean±SD) living with prediabetes were randomized to CHOICE (n=24), IM-HIIT (n=21), or IM-MICT (n=23). After an initial supervised training period (6 sessions over 3 weeks) participants exercised unsupervised on their own in free-living conditions for 6 months. A ramp increase cycle ergometer test to exhaustion was conducted by the same technician pre- and post-testing to determine VO2peak. Missing data was accounted for using linear interpolations generated with SPSS®v.20.0. RESULTS: ANCOVA results with baseline CRF as a covariate revealed no significant differences between increases in absolute VO2peak (CHOICE: 0.38, 95% CI; 0.20, 0.55, vs. IM-HIIT: 0.56, 95% CI; 0.37, 0.74 vs. IM-MICT: 0.30, 95% CI; 0.12, 0.48 L/min, F2,64=1.99, P=.14), with similar findings for relative VO2peak (F2,67=0.32, P=.73). Within group changes over time indicated small effect sizes (Hedge’s g) for increases in absolute (CHOICE= 0.00; HIIT = 0.26; and MICT=0.01) and relative VO2peak over time (CHOICE = 0.11; HIIT = 0.33; and MICT=0.15). CONCLUSION:Changes in CRF between groups randomized to perform HIIT or MICT, or given the choice of HIIT or MICT, were not significantly different at 6-months post-intervention. Providing choice for selecting HIIT or MICT did not appear to enhance the benefits of exercise for improving fitness in low active adults. Supported by the Research Endowment from the American College of Sports Medicine Foundation.