An understanding of stress and coping are important to health promotion and disease prevention. Previous research suggested that exercise can be beneficial for people who experience psychological distress. Moreover, psychological benefits following acute exercise have been frequently documented. However, there are mixed results for inactive individuals. Specially, exercise intensity has been shown to moderate the psychological benefits of acute exercise in this population. In addition, the mechanisms responsible for improvements in affective states with acute exercise remain unclear.
The primary purpose of this study was to examine psychological responses to self-selected and imposed-intensity acute exercise in inactive women with high levels of stress. Women are more likely to be inactive than men, and women are at greater risk of depression, which has been associated with chronic stress. The secondary purpose of the study was to examine potential psychobiological mechanisms (i.e., HPA axis influences and self-efficacy) for changes in psychological states.
This study used a 2 factor within-subjects experimental design with 3 treadmill exercise conditions (self-selected intensity, 10% above and 10% below relative self-selected intensity). Affective responses and salivary cortisol were measured at 6 time points, including pre-, during, & post-exercise, and self-efficacy was measured at 3 time points.
The results showed that acute bouts of exercise at around and lower intensity than ventilatory threshold might generate positive affective responses during and after exercise in young low active women with high levels of stress. The total workload of 150 kcal from exercise is effective for generating positive affect. Self-selected intensity may be effective for eliciting more favorable experiences during and following acute bouts of exercise, and promote future intentions for exercise more than exercise intensities that are imposed by someone else. In addition, the results of the present study provide partial support for the hypothesis that self-efficacy during exercise may be a potential mechanism underlying the generation of positive affective responses at self-selected intensity. We cannot draw conclusion from our results as to whether the HPA axis activity is a plausible mechanism for changes in affective responses to exercise.
Our findings support the notion that positive affective responses and self-efficacy are important predictors for intentions for future exercise. Specifically, more affective variables were found to be strong predictors of intentions at the self-selected intensity condition. It may indicate that self-selected intensity exercise has a positive influence on future intentions.