Abstract
Research has demonstrated the anxiolytic and affective changes following resistance exercise. However, several studies have allowed the participants to leave the testing facility and return at a later time to complete psychological assessments. This weakens internal validity, making it impossible to interpret findings as due to exercise per se. To address this issue, 23 male participants were randomly assigned to either a "stay" or "go" group. Within each group, all participants completed a non-exercise control session and a weight-training session based on 50% of their one repetition maximum for each of five exercises. All participants remained in the laboratory for 60 minutes following each session, at which time only those in the "go" group left the laboratory and returned at 90 and 120 minutes for their remaining affective assessments. The results indicate that despite transient disruptions in mood, an acute bout of resistance exercise results in positive psychological changes that occur within 60 minutes after completion of the exercise session and which persist up to 120 minutes post-exercise. Allowing participants to leave the laboratory or requiring them to remain in the testing environment was found to lead to different patterns of affective responses during the post-exercise assessment period. Future researchers must take into account such methodological issues when designing acute exercise studies requiring extended periods of post-exercise assessment.