The Effect of Muscle Strength and Visual Contrast Sensitivity on Fall Risk Sway Velocity Index.

Objectives: The purpose of this study was to examine if fall risk scores were affected by the interaction between muscle strength and visual contrast sensitivity.

Methods: Ninety-one individuals aged 19-79 years completed assessments of knee extension strength, visual contrast sensitivity, and fall risk. Correlations and moderation analysis were completed in combination with analysis of variance. Data were categorized into groups: 1) higher strength-higher visual contrast sensitivity, 2) higher strength-lower visual contrast sensitivity; 3) lower strength- higher visual contrast sensitivity, and 4) lower strength-lower visual contrast sensitivity.

Results: Knee extension strength via peak torque relative to body mass (R= -0.57, P<0.001) and visual contrast sensitivity (R=-0.63, P<0.001) were both negatively correlated with age, while fall risk scores were positively correlated with age (R=0.34, P=0.001). The interaction between muscle strength and visual contrast sensitivity was a significant predictor of fall risk scores (t=2.420, P=0.018) when controlling for age. Participants exhibiting lower strength-lower contrast sensitivity (12.96 ± 1.93) had significantly worse fall risk scores compared to higher strength-higher visual contrast sensitivity (11.53 ± 1.75, P=0.045).

Conclusion: Lower levels of lower body muscle strength combined with lower visual contrast sensitivity interact to negatively influence fall risk.