Does BMI Determine Obesity Levels In High School Football Players?

Abstract

PURPOSE: To determine if BMI is a valid measure of overweight or obesity levels in high school football players. METHODS: 71 males participated in the study. Body weight (BW), height (HT), BMI, body fat percent (BF%), fat mass (FM), and fat-free mass (FFM) were determined in the early am after an overnight fast. Air displacement plethysmography was used to determine BF%, FM, and FFM. BF% ≤ 20% was considered Normal; BF% 20.1%-30% was considered Overweight; BF% >30% was considered Obese. Subjects were split into three position groups: big (BIG) (lineman); athletic (ATH) (quarterbacks, tight ends, running backs, linebackers); and skilled (SKL) (wide receivers, defensive backs). Descriptive statistics and frequency distributions were calculated for each dependent variable. RESULTS: 45 (65.2%) of the subjects had a BF% ≤ 20% (Normal), 18 (26.1%) had a BF% between 20.1%-30% (Overweight), and 6 (8.7%) had a BF% > 30% (Obesity). Based on age-adjusted BMI, 26 (36.6%) of those tested had a BMI between the 5th-85th percentile (Normal), 21 (29.6) had a BMI between the 85th-95th percentile (Overweight), and 24 (33.8%) had a BMI between the 95th-99th percentile (Obese). Based on BMI 45 (63.4%) of the subjects are overweight or obese, conversely by BF% only 26 (36.6%) are overweight or obese. 39 of 69 (56.5%) athletes were misclassified as overweight or obese by BMI compared to BF%. Misclassification by group was 20 (74.1%) in BIG, 13 (54.2%) in ATH, and 6 (33.3%) in SKL when using BMI compared to BF.TABLECONCLUSIONS: Use of age-adjusted BMI percentile rank in high school football players is not effective for determining overweight/obesity levels as it leads to misclassification of overweight and obese status. This is especially true for BIG athletes (lineman).