ORIGINAL ARTICLE  BODY COMPOSITION, NUTRITION AND SUPPLEMENTATION 

The Journal of Sports Medicine and Physical Fitness 2023 October;63(10):1069-74

DOI: 10.23736/S0022-4707.23.14913-9

Copyright © 2023 EDIZIONI MINERVA MEDICA

language: English

The effect of acute hydration on body composition assessed by multi-frequency and single-frequency bioelectrical impedance

Soolim JEONG, Ryan BONNER, Averi FIRARI, Stephanie KURTI, Michael J. SAUNDERS, Christopher J. WOMACK ✉

Human Performance Laboratory, Department of Kinesiology, James Madison University, Harrisonburg, VA, USA

BACKGROUND: Multi-frequency bioelectrical impedance (MF-BIA) provides an estimate of total body water. However, it is unknown if MF-BIA detects body water increases due to acute hydration, thus affecting the validity of MF-BIA body composition measurements. The purpose of this study was to compare the effects of pre-testing fluid ingestion on body composition estimation using single-frequency bioelectrical impedance (SF-BIA) and MF-BIA.
METHODS: Thirty-nine subjects (20 male, 19 female) were tested for body composition using DXA, SF-BIA and MF-BIA before and after consumption of 2 L of water.
RESULTS: Hydration significantly increased fat percentage in men and women for MF-BIA (+2.1±0.7% for men, +2.6±0.7% for women) and SF-BIA (+1.3±0.7% for men, +2.1±0.9% for women). Additionally, hydration significantly increased fat-free mass (FFM) for DXA (+1.4±0.8 kg for men, +1.7±0.4 kg for women) and SF-BIA (+0.5±0.6 kg) in men. Hydration significantly increased fat mass (FM) for all modes (DXA +0.3±0.3 kg, MF-BIA +2.0±0.7 kg, SF-BIA +1.3±0.6 kg) in males, and only for MF-BIA (+2.2±0.3 kg) and SF-BIA (+1.7±0.5 kg) in females. Increases in FM were highest for MF-BIA for both males and females. Total body water was unchanged in males and significantly decreased with acute hydration in females.
CONCLUSIONS: MF-BIA improperly categorizes increased mass due to acute hydration as fat mass, resulting in an increase in measured body fat percentage. These findings confirm the need to standardize hydration status for body composition measurements using MF-BIA.

KEY WORDS: Body composition; Electric impedance; Organism hydration status