Date on Master's Thesis/Doctoral Dissertation


Document Type

Doctoral Dissertation

Degree Name

Ph. D.



Committee Chair

Speck, Barbara Jean

Author's Keywords

Physical activity; Determinants; Children; Childhood obesity


Physical fitness for youth; Physical fitness for children; Exercise for youth; Obesity in children--Prevention


Introduction: Childhood obesity has become a national public health crisis in America. Physical activity has been shown to be one key for controlling childhood obesity, but little is known about the mediators and moderators in physical activity promotion models. In particular, the immediate time afterschool provides an important opportunity for children to be active, only 20% of their afterschool time is used for physical activity. Purpose: The purposes of this study were to explore the psychosocial and environmental determinants of physical activity, and to examine the influence of wearing pedometers on the hypothesized determinants (physical activity self-efficacy, physical activity enjoyment, perceived parental influence, and perceived environment) of physical activity, among elementary school children attending afterschool programs, Methods: A cross-sectional correlational design was used to explore the determinants of physical activity in 133 children enrolled in afterschool programs. In addition, a pretest-posttest study was conducted to examine the influence of wearing pedometers on the hypothesized determinants of physical activity among a subsample of 50 randomly selected children. Children's physical activity levels were assessed by a seven-day recall scale, and seven consecutive days’ pedometer steps. Results: Approximately 49% of the children were overweight or obese, but only 13% of the children met national physical activity recommendations. Overweight or obese children took fewer pedometer steps than non-overweight children, and pedometer steps were negatively related to children's BMI. Wearing pedometers did not have a significant influence on the hypothesized determinants of physical activity. No evidence of the reactivity of wearing pedometers was found. Perceived parental influence partially mediated the relationships of physical activity self-efficacy and physical activity enjoyment with physical activity. For self-reported physical activity levels, physical activity enjoyment had the strongest effect on physical activity followed by physical activity self-efficacy. Perceived parental influence had the strongest effect on physical activity measured by pedometers. Conclusions: Pedometers are a reliable measurement instrument to assess elementary school children's physical activity. Perceived parental influence has the primary effect on children's self-reported physical activity levels and number of pedometer steps. Future physical activity interventions should target parental influence to improve children's physical activity levels and control childhood obesity.