Creation of a Correction Factor via Allometry to Eliminate Body Mass Influence on the Army's Physical Fitness Test

Abstract

We previously reported via allometry the Army's Physical Fitness Test (APFT) should be scaled either by event or total score to mitigate body mass (BM) on results for men. PURPOSE: Create a correction factor which eliminates lean body mass (LBM) influence on the APFT. METHODS: Male (n = 377) & female (n = 94) college-age students were tested during two graded periods on the APFT. Percent body fat was assessed via sum of three skinfolds.TableAllometry exponents (AE) with 95% Confidence Intervals (CI) were created for each event & total score (Men = −.23 (−.13 to -.33); Women = −.20 (+.08 to -.48) (95% CI) based on the influence of LBM only. A multivariate model (HT & LBM) indicated HT was not significant; thus, adjusting by LBM appeared warranted. RESULTS: Because the women's 95% CI included zero, we determined that no adjustment should be made to the women's APFT score. Opting for a single APFT adjustment for men, group BM mean was set as the reference standard to create a correction factor: (BM.23 *81.1(−.23)), such that this quantity would be multiplied by APFT score to yield an adjusted score free of LBM bias. Using simple regression, a more user-friendly expression of this correction factor, the Composite Score Adjustment (CSA) was determined as CSA = .77 + .0028* BM (kg). We compared CSA (LBM-free APFT score) to: allo metric ally scaled score (adj R2 = .995), LBM (adj R2 = .0003) & BM (adj R2 = .007), thus LBM & BM influences are removed. The CSA's for a 64 kg and 118 kg man would yield a 5% lower and a 10% higher APFT score respectively. CONCLUSIONS: LBM adjustment factors are necessary regarding the APFT score for men but not women. The user-friendly CSA's for the APFT are valid and appropriate for men. Furthermore, this convention may be appropriate for other fitness tests.