Exercise does not feel the same when you are overweight: the impact of self-selected and imposed intensity on affect and exertion

Objective: The lower rates of adherence to physical activity commonly found among overweight adults compared to their normal-weight counterparts might be due to the activity being experienced as more laborious and less pleasant, particularly when its intensity is prescribed ( or imposed) rather than self-selected. Design: Within-subject design, with two 20-min sessions of treadmill exercise, one at self-selected speed and one at imposed speed, 10% higher than the self-selected. Subjects: A total of 16 overweight (BMI: 31 kg/m(2)) and 9 normal-weight (BMI: 22 kg/m(2)) previously sedentary but healthy women ( age: 43 years). Measurements: Heart rate, oxygen uptake relative to body weight, and ratings of perceived exertion and pleasure-displeasure were assessed every 5 min. Results: The overweight women showed higher oxygen uptake and perceived exertion than the normal-weight women during both sessions. Although the two groups did not differ in ratings of pleasure-displeasure during the session at self-selected speed, only the overweight women showed a significant decline when the speed was imposed. Conclusions: Imposing a speed that is just 10% higher than what overweight women would have self-selected led to a significant decline in reported pleasure. Over time, this could diminish the enjoyment of and intrinsic motivation for physical activity, reducing adherence.