# A More Comfortable Method for Hydrostatic Weighing: Head above Water at Total Lung Capacity

## TL;DR

This study finds a more comfortable way to do hydrostatic weighing by keeping the head above water and taking a deep breath, making the process more accessible and enjoyable.

## Contribution

The study introduces a more comfortable method for hydrostatic weighing by using head above water and total lung capacity.

## Key findings

- Keeping the head above water increased body fat percentage estimates compared to head below water.
- Using total lung capacity decreased body fat percentage estimates compared to residual volume.
- For males, head above water at total lung capacity significantly lowered body fat estimates compared to head below water at residual volume.

## Abstract

Hydrostatic weighing (HW) requires full submersion with the lungs at residual volume (RV) which is uncomfortable. Therefore, the purpose of this study was to find a more comfortable way to complete HW. A HW system was used to complete three comparisons: comparison 1: change in head position (head above water vs. head below water (HAW vs. HBW)), comparison 2: change in lung volume (total lung capacity (TLC) vs. RV), and comparison 3: change in head and lung volume changes. Participants were separated by males (n = 64) and females (n = 58). Comparison 1: HAW resulted in higher mean percent body fat (PBF) than HBW (4.5% overall, 3.8% in males, 5.4% in females, p < 0.05). Comparison 2: TLC resulted in lower mean PBF than RV (5.1% overall, 5.3% in males, 4.8% in females, p < 0.05). Comparison 3: HAW@TLC resulted in significantly lower (1.5% lower, p = 0.003) mean PBF for males but was not significantly lower for females or overall (0.6% higher, p = 0.39, 0.6% lower, p = 0.18, respectively) compared to HBW@RV. In conclusion, keeping the head above water and taking a deep inhale makes HW a more enjoyable, and accessible experience for everyone while still producing accurate PBF results.