# Neuromuscular adaptation and postural muscle activity patterns during visual virtual reality stimulation: age-related differences between young and older adults

## TL;DR

This study explores how young and older adults adapt their muscle activity when using virtual reality to simulate a rollercoaster ride, finding that repeated exposure improves postural stability.

## Contribution

The study reveals age-related differences in neuromuscular adaptation to VR-induced postural challenges and shows that repeated exposure reduces muscle activation in both age groups.

## Key findings

- First VR session caused significantly increased EMG amplitudes in both young and older adults.
- Older adults showed greater increases in EMG amplitudes compared to young adults.
- Repeated VR sessions led to decreased EMG amplitudes in both age groups, indicating adaptation.

## Abstract

Vision provides important sensory input to postural control. Medical conditions and aging affect sensory—Central Nervous System (CNS) interactions, causing mismatches. Virtual Reality (VR) may address these by promoting recalibration from vision to other systems. Twenty-eight young adults (17 males, mean age 25.3 years) and 25 older adults (14 males, mean age 74.8 years) were included. Electromyography (EMG) was recorded while the participants performed, while standing, 2 control tests in quiet stance with eyes open and closed and thereafter repeatedly five times watching the same 120-second VR simulation of a rollercoaster ride. The older group watched a less challenging rollercoaster ride. Muscle activation patterns in four postural muscles; gluteus medius, medial gastrocnemius, tibialis anterior, and peroneus longus. were recorded bilaterally. The first VR session produced a marked stability challenge, reflected by significantly increased mean (p ≤ 0.008) and SD (p < 0.001) EMG amplitudes in both young and older adults in all four muscles. Both mean (p < 0.001) and SD (p < 0.001) EMG amplitudes increased more among the older adults than in young adults in all four muscles. Repeated VR sessions led to progressively decreased mean (p < 0.001) and SD (p ≤ 0.003) EMG amplitudes compare to the first VR session in both young and older adults in all muscle groups. Both age groups could quickly reduce the effects of the VR challenges when allowed to familiarize themselves with the situation during repeated sessions. Postural control adaptations enabled modulation of both the degree of muscle activation measured with EMG amplitudes and muscle group activity patterns to address stability challenges.