Slowed somatosensory conduction contributes to heightened postural instability and reduced proprioception among persons with multiple sclerosis (PwMS). Despite these delays, previous studies have noted increased proprioceptive reliance for balance in PwMS. The combination of heightened proprioceptive reliance and slowed signal transduction poses challenges in maintaining balance for MS individuals that may contribute to increased fall risk. Our lab has shown backward walking (BW) is more sensitive to detecting falls than forward walking (FW). During BW, there is increased dependence on proprioception due to the elimination of visual cues. However, no study to date has objectively established a definitive relationship between proprioception and BW. Therefore, the objective of this study is to examine the contributions of proprioception to BW compared to FW.

Thirty-five participants (average age:51.20±11.46, median PDDS:1) have completed the study. Participants completed BW and FW at both comfortable and fast speeds. We have previously established vibration sensation as a proxy measure for proprioception. Vibration thresholds were quantified at the great toe bilaterally using a two-alternative forced-choice procedure.

Significant correlations were seen for vibration sensation and FW comfortable (r=0.59; p<0.01), FW fast (r=0.60; p<0.01), BW comfortable (r=0.67; p<0.01), and BW fast (r=0.65; p<0.01). After controlling for age, sex, and PDDS, vibration sensation significantly predicted performance during all walking tasks, with larger Beta coefficients seen during BW (comfortable β=0.75; fast β=0.74) compared to FW (comfortable β=0.67; fast β=0.70).

Given the marked decline in proprioception among individuals with MS and the evident differences in proprioception between fallers and non-fallers in prior studies, there is significant clinical relevance in conducting fall risk assessments and interventions that evaluate and enhance proprioception. Due to its heightened proprioceptive reliance, BW not only provides a more effective approach to assessing fall risk but may potentially represent a more efficacious exercise intervention modality.

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