Correlation between physical activity with body mass index and body fat percentage: A study of final year students in junior high school

Study purpose. This study aims to determine the relationship between physical activity (PA), body mass index (BMI), and body fat percentage in final-year students at the junior high school level. Methods. This research is quantitative with a correlational research design. The subjects in this study were 9th-grade students at SMP Negeri 1 Jogoroto who were selected using random sampling techniques. A total of 58 students (29 boys and 29 girls) were randomly selected and volunteered to participate in this study. PA levels were measured using the IPAQ questionnaire, body fat percentage was measured using the Tanita InnerScan Body Composition Monitor scales model BC-541, and BMI was obtained from the formula = body weight (kg)/body height² (m). The data analysis technique uses descriptive statistical tests and Spearman’s rho rank correlation with the help of Microsoft Excel 2016 and SPSS version 25. Results. The results of the correlation test show that the correlation coefficient is negative and the significance is greater than 0.05 between PA and BMI (r = −0.162, p = 0.225 > 0.05) and body fat percentage (r = -0.095, p = 0.480 > 0.05). It can be said that these two relationships are weak, while BMI and body fat percentage have a positive correlation and significance less than 0.05 (r = 0.779, p = 0.000 < 0.05), indicating that BMI and body fat percentage have a strong correlation. Conclusions. The conclusion is that PA is negatively correlated with BMI and body fat percentage, although neither relationship is significant. However, BMI was found to have a positive and significant correlation with body fat percentage in students. Therefore, it is recommended that students maintain their PA in line with WHO recommendations and keep their BMI within the normal range. If your BMI is normal, it is likely that your body fat percentage is also normal.