UC Irvine

Research examined the effects of a supervised physical activity program on potential psychosocial mediators and determined whether changes in these psychosocial variables predicted changes in physical activity and fitness. Sedentary adolescent females were assigned to an intervention (n = 79) or comparison (n = 67) group. Cardiovascular fitness (cycle ergometer), physical activity (3-Day Physical Activity Recall), and psychosocial variables related to physical activity (i.e., self-efficacy, perceived barriers, social support, enjoyment) were assessed at three time points over the 9-month study. An intention-to-treat analysis showed that the intervention did not impact any of the psychosocial variables, with the exception of perceived barriers, which increased in the intervention group. Longitudinal analyses showed that improvements in fitness were associated with positive changes in global self-efficacy and exercise enjoyment. Psychosocial variables did not mediate the program's effects on fitness or activity. However, individual level changes in psychosocial variables were related to changes in cardiovascular fitness.