Association Of Body Fat And BMI With Perceived Exertion During Exercise In 18-20-year-olds

PURPOSE: Anthropometric factors, such as body fat percentage (BF%) and body mass index (BMI), may be associated with exercise performance and perceived effort, potentially affecting individualized exercise prescriptions. BF% is a measure of body fat relative to lean mass, while BMI (kg/m2) does not distinguish between body fat and lean mass. Rating of perceived exertion (RPE) represents an individual’s self-perceived experience of intensity during exercise. This study aimed to investigate associations between BF% and BMI with RPE during aerobic stepping in 18-20-year-olds. METHODS: Seventy-two participants (mean age 19.0, SD 0.81 years; 51.4% female) underwent BF% (Tanita scale) and BMI measurements (standard height and weight protocols). Participants completed a 5-minute aerobic stepping bout guided by a metronome set at 88 beats/min. RPE was assessed using the 6-20 Borg Scale during the final 30 seconds of exercise. Multiple regression analysis was conducted to evaluate the relationship between BF% and BMI with RPE. RESULTS: Mean ± SD values for BF%, BMI, and RPE during exercise were 14.3% ± 7.8%, 24.0 ± 4.7 kg/m2, and 9.9 ± 2.2 for males, and 26.6% ± 7.6%, 23.9 ± 4.8, and 11.3 ± 2.7 for females, respectively. A significant positive association was observed between BF% and RPE (β = 0.118, p = 0.007), indicating that higher BF% was associated with increased perceived exertion. BMI did not show a statistically significant relationship with RPE (β = -0.058, p = 0.503). Overall, the model explained approximately 14.5% of the variance in RPE (R2 = 0.145). CONCLUSIONS: BF% had a stronger positive association with perceived exertion compared to BMI. Incorporating BF% into prescription of aerobic exercise intensity may aid in developing more personalized training programs. Future research should explore this relationship further in other populations and in relation to more direct measures of intensity, including oxygen cost of exercise. Supported by: NIH NICHD-R01HD105768