Comparison of corticomuscular coherence under different balance paradigms in individuals with and without forward head posture

Abstract

A prospective case control investigation was conducted to assess corticomuscular coherence (CMC) under different balance conditions in order to identify alterations that may arise due to forward head posture (FHP). Sixty-four participants (between the ages of 18–25) were recruited for this study. Participants were free from any musculoskeletal symptoms and matched for relevant demographic variables. Participants were assessed for FHP using the craniovertebral angle (CVA) and separated into either the normal head posture (NHP) group by CVA > 50° or the FHP group by CVA < 50°. Participants were evaluated using the Biodex balance system while both EEG and EMG signals which were acquired simultaneously to investigate CMC. Balance was investigated under four conditions increasing in challenge: (1) standing with eyes open, (2) standing with eyes closed, (3) unstable standing with eyes open with the Biodex set on level 8, and (4) unstable standing with eyes closed with the Biodex at level 8. In addition to recording delta, beta, theta, alpha, and gamma waves, we calculated both peak and average coherence values from the CMC analysis. Statistically significant differences were identified for the FHP group vs. the NHP group for both peak (p < .001) and average CMC values (p < .001) and for the interaction of balance difficulty (stage 1 vs. stage 4), p < .01. Similarly, all brain waves (delta, beta, theta, alpha, and gamma) demonstrated statistically significant differences between the NHP and FHP groups (p < .001) and for increasing balance difficulty across the four stages, p < .05. This study demonstrates that FHP is associated with a significant elevation of CMC, a unique compensatory burden on the brain, particularly during physically challenging balance tasks.

Keywords: Forward head posture, Balance, Corticomuscular coherence, Sagittal balance