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New Equations for Hydrostatic Weighing without Head Submersion.

Jeff C Tesch1, Panayiotis Papadopoulos2, Forrest Dolgener3

  • 1EXERTECH, Dresbach, MN 55947, USA.

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|September 22, 2022
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Summary

New equations accurately predict body density using hydrostatic weighing with the head above water (HWHAW). This method, incorporating head volume prediction (HVPRED), proved equivalent to traditional head-below-water techniques for body fat percentage measurement.

Keywords:
body compositionbody fat percentdensitometryhydrodensitometryunderwater weighing

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Area of Science:

  • Exercise Physiology
  • Body Composition Analysis
  • Biomedical Engineering

Background:

  • Hydrostatic weighing is a criterion method for body density (DB) and body fat percentage (BF%) assessment.
  • Traditional hydrostatic weighing requires submersion of the head below water (HWHBW), which can be uncomfortable for some individuals.
  • Head volume estimation is crucial for accurate DB calculation when the head remains above water (HWHAW).

Purpose of the Study:

  • To derive and validate new equations for predicting body density (DB) using hydrostatic weighing with the head above water (HWHAW).
  • To develop predictive equations for head volume (HVPRED) to correct HWHAW measurements.
  • To compare the accuracy and reliability of HWHAW with HVPRED against traditional HWHBW criterion methods.

Main Methods:

  • New equations were developed to predict body density (DB) via HWHAW, using HWHBW as the criterion in 90 subjects.
  • Head volume by immersion (HVIMM) was calculated by subtracting mass in water with the head below water (MWHBW) from mass in water with the head above water (MWHAW).
  • Prediction equations were validated in 45 additional subjects using equivalence testing, regression, Bland–Altman plots, and paired t-tests.

Main Results:

  • Head girth, face girth, and body mass were the best predictors for head volume prediction (HVPRED).
  • Equivalence (±2% fat by weight) was demonstrated between body fat percentage (BF%) by HWHBW and BF% by HWHAW with HVPRED in both male and female validation groups.
  • Variance in computer-averaged samples of MWHAW was significantly less than MWHBW, and prediction error was smaller for BF% by HWHAW with HVPRED.

Conclusions:

  • Body fat percentage (BF%) measurements using HWHAW with HVPRED are equivalent to those obtained by HWHBW.
  • The developed prediction equations provide a valid and potentially more comfortable alternative for body composition assessment.
  • HWHAW with HVPRED demonstrated smaller weight fluctuations compared to HWHBW.