# Sex Differences in Foot Arch Structure Affect Postural Control and Energy Flow During Dynamic Tasks

## TL;DR

This study found that sex differences in foot arch structure affect how people maintain balance and transfer energy during movements like sitting to standing.

## Contribution

The study reveals novel sex-specific biomechanical differences in postural control and energy flow during dynamic tasks.

## Key findings

- Males have stiffer foot arches and show more efficient postural control during sit-to-stand tasks.
- Females make more frequent postural adjustments, which may increase injury risk due to higher mechanical loading on knees and ankles.
- Energy flow patterns differ between sexes, with males showing higher thigh and shank joint power during sit-to-stand.

## Abstract

Background: This study investigated sex differences in foot arch structure and function, and their impact on postural control and energy flow during dynamic tasks. Findings aim to inform sex-specific training, movement assessment, and injury prevention strategies. Methods: A total of 108 participants (53 males and 55 females) underwent foot arch morphological assessments and performed a sit-to-stand (STS). Motion data were collected using an infrared motion capture system, three-dimensional force plates, and wireless surface electromyography. A rigid body model was constructed in Visual3D, and joint forces, segmental angular and linear velocities, center of pressure (COP), and center of mass (COM) were calculated using MATLAB. Segmental net energy was integrated to determine energy flow across different phases of the STS. Results: Arch stiffness was significantly higher in males. In terms of postural control, males exhibited significantly lower mediolateral COP frequency and anteroposterior COM peak velocity during the pre-seat-off phase, and lower COM displacement, peak velocity, and sample entropy during the post-seat-off phase compared to females. Conversely, males showed higher anteroposterior COM velocity before seat-off, and greater anteroposterior and vertical momentum after seat-off (p < 0.05). Regarding energy flow, males exhibited higher thigh muscle power, segmental net power during both phases, and greater shank joint power before seat-off. In contrast, females showed higher thigh joint power before seat-off and greater shank joint power after seat-off (p < 0.05). Conclusions: Significant sex differences in foot arch function influence postural control and energy transfer during STS. Compared to males, females rely on more frequent postural adjustments to compensate for lower arch stiffness, which may increase mechanical loading on the knee and ankle and elevate injury risk.