Low adherence and high dropout contribute to physical inactivity but their psychological mechanisms remain poorly understood. Behavioral decision-making in the context of exercise has been assumed to rely on rational cognitive processes. However, cognitive models leave most of the variance in behavioral choices unaccounted. An alternative suggests that affective constructs, such as pleasure-displeasure, may have considerable explanatory potential.
PURPOSE: Kahneman (e.g., Kahneman et al., 1993; Varey & Kahneman, 1992) proposed that certain parts of the affective experience associated with an event (i.e., its peak and its end) act as heuristics that drive decision-making (termed "the peak-and-end rule"). On the other hand, the duration of the event does not seem to be influential (termed "duration neglect"). In this study, we tested the "end rule" and "duration neglect" in the context of exercise.
METHODS: The participants were 16 M & 15 F overweight, low-active adults (mean age 21.4 yr). Declines in pleasure during 20 min of treadmill exercise were induced by setting the intensity 10% above ventilatory threshold. The "end" affective experience and the total duration of the bout were manipulated in a counterbalanced within-subject design by either having the participants stop immediately or after a 5-min cool-down. Pleasure-displeasure was assessed with the Feeling Scale. In a final session, participants were given the choice to repeat one of the two previous exercise bouts.
RESULTS: Affect became significantly less positive during the 20-min bouts and improved during the cool-down. Consistent with the hypotheses, at a 2:1 ratio, the participants chose to repeat the exercise bout that ended positively (even though it was longer) over the one that ended negatively (Chi-square=3.9, P<0.05).
CONCLUSIONS: Providing exercisers with a more pleasant "end" could influence subsequent exercise decisions, even if this results in performing more exercise. These data could help explain why intensity has been associated with reduced adherence among sedentary adults but duration has not (Perri et al., 2002) or why obese adults offer to exchange longer duration for lower intensity (Fogelholm et al., 2000).