A full-factorial test of motivational and volitional intervention strategies for promoting exercise habit formation and exercise maintenance among new users of an online exercise class platform.

Interventions often fail to achieve long-term behavioral maintenance. Utilizing motivational and volitional strategies to promote behavioral maintenance factors may improve this. Using a full-factorial experiment, we tested the effects of three intervention components (focused on intrinsic motivation and identity, exercise preparation habit, and exercise instigation habit) on exercise participation over a year, among new users (N = 751; 91% identifying as female, 54% identifying as White race) of a global, online exercise class platform, run by Les Mills International Ltd, called LM+. We also tested the intervention components' theoretical mechanisms of action-habit formation, intrinsic motivation, identity, and self-efficacy. Multi-level models found some support for a main effect of the exercise preparation habit intervention component in promoting self-reported and objective exercise participation (behavioral outcomes measured via monthly surveys and the LM+ platform; mechanisms measured via monthly surveys)-in particular online exercise class frequency (fixed effect estimate = 0.84, p < 0.05, and = 0.12, p < 0.05, respectively). The preparation habit component also significantly increased preparation habit strength (0.30, p < 0.05) and instigation habit strength (0.33, p < 0.05). Other expected effects were nonsignificant. Helping individuals form an exercise preparation habit may facilitate initiating and maintaining exercise over time, in particular for attending online exercise classes, potentially through promoting greater preparation and exercise instigation habit strength.