Why do they do (h)it? Using Self-Determination Theory to understand why people start and continue to do high intensity interval training (HIT) group exercise classes

High-intensity interval training (HIT) has emerged in recent years as an alternative form of exercise for health improvement. However, due to the maximal or near maximal effort nature of HIT there have been questions regarding the appeal of HIT, and the likelihood that individuals will maintain involvement over time. Limited research has considered the motivational processes influencing participation in HIT. The objective of this qualitative study was to use Self-determination Theory as a framework to understand the reasons why exercisers start and maintain their involvement in HIT group exercise classes, and how a HIT environment may support their motivation. Semi-structured interviews were conducted with 12 purposively sampled participants (mean age = 22.75 years) who had regularly attended HIT group exercise classes for ≥6 months. Interviews were digitally recorded, transcribed and data were thematically analysed incorporating inductive and deductive procedures. Participants started and continued HIT for a number of reasons that were mainly intrinsic and underpinned by behavioural regulations predominantly reflective of autonomous motivation. Participants identified a broader range of reasons for continuing HIT than starting HIT. The HIT structure, HIT exercises, instructors and other class attendees created an environment that supported autonomy, competence and relatedness. Some individuals can be motivated to participate in HIT for reasons that are positively associated with adaptive behavioural, affective and cognitive outcomes. HIT classes can be designed to support needs satisfaction and promote continued engagement.