PP1417 - The Influence of Yoga Training on Functional and Physiological Measures of Balance

Abstract:
This study aimed to examine the impact of regular yoga practice on three physiologic measures of the vestibular system- the video Head Impulse Test (vHIT), cervical and ocular Vestibular Evoked Myogenic Potential tests (cVEMP and oVEMP), as well as one functional balance measure- the modified Clinical Test of Sensory Integration and Balance (mCTSIB). A young adult sample who regularly practiced yoga was compared to a sample of healthy young adults who did not regularly exercise. Although no statistically significant group differences were revealed, the yoga group had observably lower sway values on the mCTSIB, particularly for the most difficult condition.

Summary:
Background/Study Purpose
Falling, and the risk of falling are large problems for older adult populations. Although many risk factors for falling are non-modifiable, including balance disorders, normal age-related changes can impact balance & gait, and increase falls risk. Physical training throughout the lifespan could be used preventatively to slow progression of these age-related changes. Previous studies have shown that some forms of physical training, including dance, may lead to improvements in balance function (Cheng et al., 2011; Borges et al., 2018).

Yoga might be a useful physical training method for improving balance function, or strengthening the vestibular reflexes, as yoga postures involve angular and linear accelerations that might stimulate the vestibular receptors, including bending forwards, to the side, or completing inversions (Prado et al., 2014). Although limited research has been conducted to determine impacts of yoga on balance function, one study revealed increased cVEMP amplitudes, and decreased asymmetry in young adults who practiced yoga vs controls (Shambhu et al., 2017). However, they did not control for tonic EMG level in their cVEMP analysis, which is known to impact amplitudes (McCaslin et al., 2014; Rosengren et al., 2015). Since yoga is a low-impact form of exercise that could potentially be implemented in older adult populations for strengthening the balance system, further research is needed to examine how vestibular pathways and structures might be impacted by yoga practice.

The purpose of the current study was to examine how yoga might impact the vestibular system, specifically in regards to the three vestibular reflexes: thevestibulo-ocular reflex (VOR), the vestibulo-collic reflex (VCR) and the vestibulo-spinal reflex (VSR).

Research questions
1) Are there group differences (between those who practice yoga and those who do not practice yoga) on measures of the VOR, specifically the video Head Impulse Test (vHIT) and the Ocular Vestibular Evoked Myogenic Potential (oVEMP)?
2) Are there group differences in responses from the VCR as measured by the Cervical Vestibular Evoked Myogenic Potential (cVEMP)?
3) Are there group differences in responses from the VSR as measured by the Modified Clinical Test of Sensory Interaction and Balance (m-CTSIB)?

Methodology
Pre-experimental measures included a pure-tone hearing assessment, the Dizziness Handicap Inventory (DHI), which was used as an exclusion criterion, a case history questionnaire, and an ocular motor screening. Experimental measures included administering the vHIT, oVEMP, cVEMP, and mCTSIB, the order of which were counterbalanced across participants.

Results/Discussion
Twenty-one subjects participated in this study (10 in yoga group, 11 in control group), all of whom were young adults (aged 18-40) with normal hearing, and no history of processing disorder, CNS disorder, or vestibular/balance dysfunction. Results revealed no significant group differences for any of the three physiologic measures (vHIT, oVEMP, cVEMP) or for the functional balance measure (mCTSIB). However, for the most difficult condition of the mCTSIB (compliant surface, eyes closed), yoga participants had notably lower mean sway excursion compared to the control group, a result which was approaching significance. Future studies might attempt to recruit larger sample sizes to evaluate the impacts of yoga on vestibular function.