This investigation examined the psychophysiological factors related to amounts of positive mood changes following aerobic exercise. Comfortable Self-Paced Running (CSPR) can be defined as running at a subjective exercise intensity of Comfortable Self-Established Pace (CSEP). Eighteen male students performed CSPR for 15 min on a treadmill. Subjects completed the Mood Check List (MCL-S.1), consisting of \u22Pleasantness,\u22 \u22Relaxation\u22 and \u22Anxiety\u22 subscales, both before and immediately after CSPR. Mean Ratings of Perceived Exertion (RPE), heart rate, and %V02max during CSPR indicated that the exercise intensity of CSPR was at a moderate level. In addition, a significant increase in \u22Pleasantness\u22 and \u22Relaxation,\u22 and a significant decrease in \u22Anxiety\u22 were found immediately after exercise. There was a significant correlation between amount of increase in both \u22Pleasantness\u22 and \u22Relaxation\u22 and a more emotionally unstable or socially inadaptable personality, lower levels of mental health, higher trait anxiety, type A behavior pattern, and more positive belief towards sport behavior. Furthermore, greater increases in \u22Relaxation\u22 were associated with lower %V02max. The results of multiple regression analyses indicated that trait anxiety and a type A behavior pattern were both significant positive predictors (74.7%) for the amount of change in \u22Pleasantness.\u22 Only trait anxiety, however, was a positive predictor (61.6%) for \u22Relaxation.\u22 These results suggest that the increase in positive mood following CSPR can be attributed more to psychological than physiological factors. In particular, high trait anxiety appears to be a strong predictor for changes in positive mood following CSPR
