Abstract
INTRODUCTION: Growing evidence indicates that moderate physical activity can influence cognition and visual cortical activity. However, little is known about the effect of physical activity on visual perception. Here we investigate for the first time whether moderate physical exercise influences temporal and spatial estimation in adult humans. METHODS: 16 adult volunteers performed a distance estimation task and a temporal estimation task in separate days and in counterbalanced order. Participants were asked to reproduce either spatial (range: 7° to 30°) or temporal intervals (range: 200ms to 3200ms). Each task was tested in three conditions: (1) a resting condition (baseline), (2) a physical activity condition (cycling in place - PA), in which the heart rate was kept constant at 40 bpm above the basal rate and, (3) after (15 to 20 minutes) physical activity (POST), when heart rate returned to the basal rate. RESULTS: We found that physical activity induced a consistent overestimation of the real duration of time intervals below the second (baseline vs. PA: t=-2.54, p<0.05, d=-0.64). Importantly, this effect persisted in the POST session (t=-3.72, p<0.05, d=-0.93), when heart rate went back to baseline levels, and no correlation was observed between the perceptual bias and heart rate in any condition. In contrast, physical activity had no effect on the spatial estimation task, where participants’ estimates were accurate across all conditions. CONCLUSIONS: Our results show that moderate physical activity has a specific impact on temporal, but not spatial perception in humans, and that the effect cannot be explained by the change in heart rate. We speculate that this effect might be mediated by an alteration of the dopaminergic and/or GABAergic systems that are modulated by physical activity and have been shown to be involved in the perception of time.