Abstract
Introduction: In-task affective responses to moderate-intensity continuous exercise training (MICT) have been shown to predict future physical activity behaviour. However, limited research has investigated whether this affect-behaviour relationship is similar for high-intensity interval training (HIIT), and whether it holds true over the longer term. Purpose: To determine if in-task affect during two weeks of supervised MICT and HIIT predicted changes to unsupervised moderate-to-vigorous physical activity (MVPA) behaviour 12 months post-intervention. Methods: A secondary analysis from a larger randomized trial, Small Steps for Big Changes (ClinicalTrials.gov # NCT02164474) was conducted. Ninety-nine adults (69.7% female; 50.9±9.4 years) who were low active and overweight were randomized to two weeks of behavioural counselling and progressive exercise training of MICT (n=52) or HIIT (n=47), followed by 12 months of accelerometry-assessed free-living MVPA. Results: The linear regression model for MICT was significant (p<.05), revealing that in-task affect during supervised training predicted 12-month change in weekly MVPA minutes. The association between in-task affect and change in 12-month MVPA in the MICT group was also significant (B=17.27, p=.038), suggesting that 12-month change in MVPA increased by 17.27 minutes/week for every one-unit increase in in-task peak negative affect. The regression model for HIIT was not significant (p>.05), revealing that in-task affect was not predictive of 12-month change in MVPA. Conclusions: The current findings suggest that the affect-behaviour relationship may vary depending on exercise type. For HIIT-based exercise in particular, additional psychological constructs beyond in-task affect should be considered when attempting to predict future physical activity behaviour.Acknowledgments: The authors would like to acknowledge all participants who took part in the Small Steps for Big Changes program.