# Investigating the impact of dehydration and hydration on In-Vivo hip soft tissue biomechanics

## TL;DR

This study shows that dehydration increases hip tissue stiffness, which could raise fall-related injury risks, especially in males and those with less fat.

## Contribution

The study is the first to investigate how dehydration affects hip soft tissue biomechanics and identifies sex and fat thickness differences.

## Key findings

- Dehydration increased peak force in hip tissues, suggesting higher injury risk.
- Males showed greater stiffness and energy absorption than females.
- Fat thickness was a key predictor of biomechanical response during dehydration.

## Abstract

Hip soft tissue biomechanics has a significant effect on hip loading and fracture risk during falls. Despite the high dehydration rate in older adults, athletes, and outdoor workers and its association with a higher risk of falls, the effect of dehydration on hip soft tissue biomechanics is unknown. Twenty participants (13 females and 7 males, aged 18–35) underwent indentation tests and ultrasound imaging over the greater trochanter in both hydrated and dehydrated states. We assessed the hydration levels using a urine color chart and measured the tissue thicknesses via ultrasound. Results showed a significant increase in peak force (from 12.67 ± 9.09 N to 15.46 ± 9.23 N, p < 0.05) under dehydration. We observed notable sex differences, with males exhibiting higher stiffness and energy absorption than females, despite variations in peak force. Fat thickness emerged as a critical predictor of biomechanical response, particularly in the dehydrated state. These findings underscore the importance of hydration in maintaining soft tissue integrity and reducing injury risks. Future work should explore chronic dehydration effects and include broader demographic variations to enhance fall prevention strategies and clinical practice. This research also highlights the need for targeted hydration management in at-risk populations.