Making the exercise experience more pleasurable: Exploring the psychological effect of allowing intensity adjustments...

Feeling good during exercise is a key predictor of whether people stay active. One factor thought to influence this is whether exercisers perceive control over their training intensity. A meta-analysis suggested this psychological effect may be negligible. However, our study suggests this conclusion should be reconsidered given prior limitations (small samples, data aggregation bias, and limited focus on the 'heavy' domain of exercise intensity). We explored affective responses to self-adjusted versus imposed intensities within the approximated heavy domain (64-76% HRmax). Sensitivity power simulations informed our sample size (N = 94; 22.7 ± 2.7 years, 49% female). Participants first completed a ramp protocol with the option to adjust intensity, followed one week later by an imposed session replicating their own pattern, without them knowing this. Affective valence was recorded every 3 min (Feeling Scale, FS), and decisional preferences assessed post-session (DPEX test). Multilevel modelling showed affective valence was 0.52 FS units lower [95% CI: -0.86, -0.18] in the imposed condition and preference for exercise also decreased (d_z = -0.45); results were robust across multiverse analyses. Small chances to adjust intensity may improve the experience, but confirmatory research is needed to test assumptions with an empirically justified smallest effect size of interest.