Skip to main content
2024 NSCA National Conference Main banner
Icon Legend
This session is not in your schedule.
This session is in your schedule. Click again to remove it.
Back

Body Composition

(05) TECHNICAL AND BIOLOGICAL ERROR OF SKELETAL MUSCLE MASS AND TOTAL BODY WATER ESTIMATION FROM MULTI-FREQUENCY BIOELECTRICAL IMPEDANCE ANALYSIS

Friday, July 12, 2024
9:30 AM – 9:45 AM East Coast USA Time
Location: Room 337-338
Abstract Details: Body composition describes and quantifies various elements within the human body and is critically involved in clinical nutrition, selected areas within many medical specialties, and components of exercise science. The ability of techniques to reliably estimate body composition is a key concern in research and athletic settings. Data obtained from bioimpedance-based devices can be used within prediction equations to estimate whole-body skeletal muscle mass (SMM) and total body water (TBW). However, limited data are available to inform the reliability of SMM and TBW estimates across multiple days.

Purpose: The purpose of this study was to determine the technical and biological error of SMM and TBW estimation from multi-frequency bioelectrical impedance analysis (MFBIA).

Methods: A sample of 17 generally healthy adults (10 F, 7 M; [mean ± SD] age: 26.2 ± 8.6 y; height: 171.0 ± 2.2 cm; weight: 66.1 ± 2.2 kg; body mass index: 22.6 ± 2.2 kg/m2) completed three total MFBIA assessments on consecutive mornings. On both mornings, participants reported to the laboratory after an overnight period of resting and fasting from food and fluid intake. MFBIA total-body SMM and TBW were estimated from appendicular lean mass and impedance index, respectively, using validated equations developed with magnetic resonance imaging and deuterium dilution data. Visit 1 consisted of back-to-back assessments, with participants stepping off the analyzer between tests. Visit 2 consisted of a single assessment the following morning. The error observed from back-to-back scans at visit 1 was considered technical error, while the error observed between scans at visit 1 and visit 2 was considered technical plus biological error. For both comparisons, the reliability of SMM and TBW estimation was quantified as precision error (PE), root mean square coefficient of variation (RMSCV), and least significant change (LSC). RESULTS: The mean ± SD SMM and TBW estimates were 24.3 ± 5.7 kg and 37.4 ± 7.5 kg, respectively. For consecutive scans at visit 1 (technical error), PE, RMSCV, and LSC for SMM and TBW were 0.1 kg, 0.4%, and 0.3 kg and 0.1 kg, 0.3 %, and 0.3 kg, respectively. When comparing scans from visits 1 and 2 (technical plus biological error), PE, RMSCV, and LSC for SMM and TBW were 0.3 kg, 1.1 %, and 0.7 kg and 0.4 kg, 1.2%, and 1.2 kg, respectively.

Conclusions: In the present analysis, within-day technical error was negligible as compared to between-day biological error. While noteworthy, this aligns with previous research reporting a relative sensitivity of bioimpedance devices to some sources of biological error. PRACTICAL APPLICATIONS: Users of bioimpedance technology should be aware of the magnitude of between-day biological errors when tracking changes over time. Changes smaller than the between-day biological error may not reflect true changes in the measured outcomes.

Acknowledgements: None