Effects of an after-school care-administered physical activity and nutrition protocol on body mass index, fitness levels, and targeted psychological factors in 5- to 8-year-olds.

Over one third of U.S. youth are overweight or obese. Treatments typically have had unreliable effects, inconsistently incorporating behavior-change theory. After-school care might be a viable setting for health behavior-change programs. We evaluated effects of two consecutive 12-week segments of a revised self-efficacy/social cognitive theory-based physical activity and nutrition treatment on fitness levels, body mass index (BMI), and targeted psychosocial factors in after-school care participants, ages 5-8 years. Changes in physiological measures, exercise self-efficacy (ESE), and physical self-concept over 9 months were contrasted in experimental (n = 72) vs. typical-care (n = 42) groups. Mediation of the group-BMI change relationship by the psychosocial factors was also assessed. Improvements in physiological measures and ESE were significantly greater in the experimental group. ESE change completely mediated the association of treatment type with BMI change. The experimental group demonstrated significantly greater improvements in the physiological measures, with its treatment's theoretical basis and application within after-school care supported.