Working it out: can an acute exercise bout alleviate memory bias, rumination and negative mood?

Although it is well known that exercise reduces depressive symptoms, the underlying psychological mechanisms remain unclear. This experimental study examined the acute effect of exercise on mood, and depressotypic memory bias and state rumination. Trait rumination was tested as a possible moderator. A sample of non-regular exercisers (N = 100) was randomized to exercise or rest. After a negative mood induction, the exercise condition cycled for 24 min at moderate intensity, while the rest condition rested. Negative and overgeneral memory bias, as well as positive and negative affect were assessed after exercise/rest. To capture the lingering of negative mood and state rumination, both were assessed multiple times throughout the study. The exercise (as compared to rest) condition reported more positive affect. However, no differences were found on overgeneral memory bias, as well as depression-specific mood or state rumination measured throughout the study. Interestingly, the exercise condition showed more negative memory bias at higher levels of rumination. Individual differences in trait rumination moderated the exercise-memory bias relation, such that exercise increased negative memory bias at higher levels of rumination. It is possible that long-term exercise protocols are necessary to change cognitive processes related to depression.