The influence of effort intensity and duration on exercise choices

BACKGROUND: Anticipation of physical effort during exercise can be off-putting or attractive, however, the causes of these distinct motivational states are not well understood. Based on this shortcoming, the present study examined a) whether the duration and intensity of effort have different motivational properties and b) if the extent that physical exercise is coherent with core values (i.e., autonomous) altered the motivational properties of physical effort. METHODS: Three studies answered these questions by giving participants 24 choices between two exercise scenarios which varied in either effort duration or intensity. Studies 1 and 2 employed hypothetical choices, and study 3 required participants to perform their choice. Multilevel binary logistic regression models were constructed to examine the research questions. RESULTS: Individuals relatively low in autonomous motivation universally avoided increasing effort intensity and duration. Moderately autonomous participants were less dissuaded by effort intensity, compared to effort duration in hypothetical choices. However, effort duration and intensity were equally undesirable during consequential choices. Highly autonomous participants were either ambivalent or attracted to both forms of effort in hypothetical choices. However, they increasingly avoided effort duration and were ambivalent to effort intensity during consequential choices. CONCLUSIONS: a) the evaluation of effort duration and intensity typically differs across hypothetical and consequential exercise scenarios, b) effort duration tends to be more costly relative to effort intensity, however, c) autonomous motivation towards exercise alters the motivational properties of effort.