Food & Health Alliance

Jamner, M. S.; Spruit-Metz, D.; Bassin, S. & Cooper, D. M.  University of California and the University of Southern California. (2004).  

Study that examined the efficacy of an intervention targeted towards at risk adolescent females in two American high schools.  The study also identified and investigated the possible mediating variables such as social support, perceived barriers, self-efficacy and enjoyment in physical activity.  The intervention consisted of 40 minutes of activity (such as swimming or Tae Bo) for four days a week, a fifth class was dedicated to education on health benefits of exercise and strategies to becoming more physically active. Classes were for females only and offered access to activities that were not usually in the physical education curriculum. 

Method:  58 10^th and 11^th grade girls were recruited, all participants had to meet criteria levels of low levels of fitness, being physically able to exercise and having a sedentary lifestyle.  Half of the participants experienced the intervention.  Measures of cardiovascular fitness, body composition, BMI percentile, physical activity levels, lifestyle activities were recorded.   A questionnaire was also administered which measured self-efficacy, barriers to participating in physical activity, social support and enjoyment in physical activity.  These measurements were taken at Time 1 and Time 2 (with four months between time points). 

Findings: The intervention was successful in raising levels of physical activity with this at risk group.  The intervention prevented the commonly reported decrease in physical activity for this age group.  The intervention group participated in 60% more physical activity than at baseline, in contrast the control groups participation in physical activity declined by 40%. Therefore the intervention group expended more energy than the control group and also reported an increase in participation in hard activity over the four-month period; in contrast no change was noted for the control group.

The intervention group engaged in significantly more lifestyle activities than the control group, these types of activities take pace outside of school and do not require supervision.  Therefore it was proven that changes in behaviour within school was generalised to outside the school environment and may make impact on the adolescent’s general lifestyles.  The intervention did not make any difference to psychological factors; with little change being observed between pre and post-test measures, therefore the intervention was not successful at changing these psychological factors. 

However, there may be other psychological measures that were not included in the questionnaire that could have been affected by the intervention.  There was a marked increase in cardiovascular fitness in the intervention group, but no effect was noted on BMI or other body composition measures, perhaps the participants increased their food intake due to participation in physical activity or the level of the exercise was not intense enough to result in changes in body composition. 

Implications:  This study indicates that a well-designed intervention can effect adolescent female participation in physical activity and, in turn, their cardiovascular fitness.  This type of intervention can emphasise to this at risk group the health benefits of physical activity.