Changes In Dual-energy X-ray Absorptiometry Body Composition Scores In Females Following Exercise-induced Body Fluid Redistribution

Immediate exercise can impact the accuracy of dual-energy x-ray absorptiometry (DXA) body composition scores via several mechanisms. Body fluid redistribution might be one of these mechanisms, which has not been adequately investigated. This is particularly important to investigate in females due to hormonal fluctuations, higher body fat percentage, and exercise habits. PURPOSE: To determine DXA score changes following exercise-induced body fluid redistribution in females. METHODS: Euhydrated (USG < 1.020) university students (n = 30) completed 30-min of upper-body exercise (UBE) at 70% of the heart rate reserve (HRR), lower-body exercise (LBE) at 70% HRR, and a seated control (CTRL). Body composition variables were assessed by DXA before and after the interventions. ANOVA (2x3) were computed to determine interactions between experimental conditions and body composition measurements. The coefficient of variability (CV%) reported consistency estimates. RESULTS: In arms, CTRL and UBE showed significant mean differences in fat tissue (M = 0.56 ± 0.20%, p = 0.009; M = 0.68 ± 0.18%, p = 0.001) and fat region (M = 0.54 ± 0.19%, p = 0.007; M = 0.59 ± 0.17%, p = 0.002). UBE also impacted tissue (M = 0.24 ± 0.03 kg, p < 0.001), lean mass (M = 0.19 ± 0.02 kg, p ≤ 0.001), and total mass (M = 0.24 ± 0.03 kg, p < 0.001). In legs, UBE affected tissue fat (M = 0.32 ± 0.14%, p = 0.025), region fat (M = 0.31 ± 0.13%, p = 0.026), and lean mass (M = 0.17 ± 0.07 kg, p = 0.021). Total body changes were significant for UBE (M = 0.11 ± 0.02 kg, p < 0.001) and LBE (M = 0.20 ± 0.03 kg, p < 0.001), as were total mass changes for UBE (M = 0.14 ± 0.03 kg, p < 0.001) and LBE (M = 0.21 ± 0.03 kg, p < 0.001). Reliability was high within experimental conditions (CV = 0.17%-3.76%). CONCLUSION: Immediate exercise led to statistically significant yet modest changes in DXA body composition scores among females, with upper-body exercise showing the most reliable and pronounced effects as shown by low coefficients of variability, underscoring the potential impact of acute exercise on body composition.