The 5K run age and weight Handicap (5KH) is a previously validated model that aims to eliminate the age and body weight (BW) biases previously noted in 5K run time (RT). In validation studies, however, not all the BW bias is removed. We hypothesized that this may be due to the influences of percent body fat (BF) and effort (RPE).
PURPOSE: To assess the contributions of BF and RPE on 5K run time (RT) above those of BW and age.
METHODS: For 99 male runners in a regional 5K race (43.9 ± 12.1 yr; 183.4 ± 28.4 lbs; 17.6 ± 6.0%), BF was estimated (Jackson Pollock sum of three skinfolds: chest triceps, subscapular) just prior to the race and RPE on the 20 pt Borg scale, was used to assess overall effort upon race completion. RTadj, the run time corrected for age and BW using the 5KH was calculated. Multiple regression analysis was used with the RT as the dependent variable and BW, age, BF, and RPE as the independent variables. Both the individual and combined effects of BF and RPE, using multiple regression of natural logs, was used to determine a new adjusted run time (NRTadj) model based on age, BW, BF and RPE.
RESULTS: With age and BW in the 5KH model, the coefficient of determination (R2) was 0.311. When BF was added, R2 = 0.433. When age, BW, and RPE were entered, R2 = 0.431. When both BF and RPE were added to age and BW, R2 = 0.522. This suggested that BF and RPE explained more variance in RT than age and BW alone. The NRTadj = RTadj / (BF0.146 * RPE-0.327) index determined via allometry was not significantly correlated with age (r2 =0.032, p = 0.076) nor with BW (r2 = 0.0038, p = 0.541).
CONCLUSIONS: The previous finding that the 5KH does not remove all BW bias is apparently accounted for by the influences of BF and RPE. Specifically, higher BF and lower RPE contribute to a slower RTadj. Since, from a health-related fitness perspective, no handicap should be awarded for higher BF and/or lower RPE, this finding suggests that the 5KH, for men, appropriately adjusts for the age and BW vs. RT biases previously noted.