Relationship between Physical Activity, BMI, and Cardiovascular Health in Ninth Grade Physical Education Students

Abstract

A national average of 47% of children are overweight or at risk for being overweight (NHANES 2001–2002). Greater numbers of this population are exhibiting comorbidities that once were strictly present in adults. In order to help reduce the number of children classified as overweight or at risk of being overweight and the early presence of adult disease, mechanisms need to be identified which contribute to this problem. PURPOSE: To determine if there is a relationship between physical activity, body mass index (BMI), and cardiovascular health. METHODS: 902 ninth grade students participated. Height and weight were assessed and used to determine BMI. Students completed the Previous Day Activity Recall self questionnaire (Weston, Petosa, Pate, 1997) to determine the amount and quality of physical activity. Students completed the one mile run to estimate VO2max. Pearson correlations were used to determine the relationship between BMI, the amount of physical activity, and VO2max. Significance was accepted at p<0.05. RESULTS: 26.8% of students were classified as overweight or at risk for being overweight, and 19.9% did not participate in at least 20 minutes of moderate to vigorous physical activity the previous day. Total physical activity pre and post school averaged 1503 ± 741 Kcals/day. The correlation between BMI, physical activity, and VO2max indicated a strong negative relationship between VO2max and BMI(−0.74 males, −0.81 females). There was a weak positive correlation between physical activity and BMI (r = 0.35). CONCLUSION: A strong significant correlation between BMI and cardiovascular health implies that a low VO2max score is a good predictor of a student being either overweight or at risk for being overweight. Secondarily, our data indicates self report physical activity levels are not strongly related to the prevalence of students who are overweight or at risk of being overweight. A combination of a weak significant correlation between physical activity and BMI, and a high rate of physical activity within this population supports this contention. Other factors such as nutrition or inflated self reported physical activity levels could explain why only 20% of the students are not participating in at least 20 minutes of moderate to vigorous activity, while 27% are overweight or at risk for being overweight.