Measurement of body fat percentage of college students and optimized selection of regressive equations

Aim: To accurately realize the obesity extent and health status of college students based on the optimized regressive equations of body fat percentage. Methods: The experiment was conducted in Hengyang Normal University between November 2004 and January 2005. Totally 142 students of Hengyang Normal University were randomly selected including professional exercise students: 69 males and 25 females; non-professional students: 25 males and 23 females. 1 The height (m) and boby mass (kg) of the students were measured and the body mass index (BMI) was calculated based on the formula: body mass/the square of height. 2 Inelastic tapeline was used to measure the waist perimeter and hip perimeter (precision: mm). The tapeline was localized at navel level to read the waist perimeter at the end of exhalation; the hip perimeter was read when tapeline was localized at the maximal perimeter level of hip. The ratio of waist perimeter to hip perimeter (WHR) was calculated. 3 Assorted regressive equations were established with body fat percentage as dependent variable, WHR and BMI as independent variables. Selection and test of reliability were applied in these equations. Based on the optimal equations, body fat percentage of college students could be estimated conveniently. Results: 1 ANOVA of body fat percentage of college students: Specialty and gender factors had significant effects on body fat percentage (P < 0.01), but had no interactions (P > 0.05). Gender had more significant effect on body fat percentage than specialty. The test power of specialty and gender factors-were both 1, indicating that the number of subjects was enough in this research. 2 Correlation analysis of body fat percentage, BMI and WHR: BMI was not the main factor that influenced the body fat percentage of college students, and it could result in more errors when estimating body fat percentage. However, WHR was superior to and more applicable than BMI in estimating body fat percentage. 3 Optimized selection of regressive equations: For the professional exerciser students: Male: ý = -66.707+99.951x, Female: ý = 558.016-1 472.6x+1 003.68 x². For the non-professional students: Male: ý = -24.899-19.842x +87.465 5 x², Female: ý= -43.506+59.55x+1.052×BMI. Conclusion: Assorted regressive equations are established with body fat percentage as dependent variable, WHR and BMI as independent variables, followed by selection and test of reliability. Based on the optimal equations, body fat percentage of college students can be estimated conveniently and effectively.