Background: The single-leg heel raise test is a common clinical assessment; however, little is known about its validity in people with multiple sclerosis (MS). This study investigated the validity of the single-leg heel raise test in a group of people with MS and a healthy control group (CTL).
Materials and Methods: Twenty-one people with MS (49 ± 12 years, Expanded Disability Status Scale 1.5–5.5) and 10 healthy controls (48 ± 12 years) performed the single-leg heel raise test, ankle plantarflexion isometric strength assessment using electromechanical dynamometry, and mobility measures (Timed 25-Foot Walk, 2-Min Walk Test, Functional Stair Test).
Results: Convergent validity between the heel raise test and strength was moderate for participants with MS completing <20 heel raises (r = 0.63, p = 0.001) but weak for the entire sample (r = 0.30, p = 0.020). Compared to the average CTL group values, the heel raise test differentiated between groups on the MS groups' weaker (p < 0.001) and stronger (p = 0.003) limbs, while strength only differentiated between groups on the weaker limb (p = 0.010). Considering the weaker and strong limbs from the MS group and the CTL group average values, the mobility measures had moderate-to-strong correlations with the heel raise test on the weaker MS limb CTL (r = 0.71–0.78) and stronger MS limb CTL (r = 0.62–0.70), and weak-to-moderate correlations with strength on the weaker MS limb CTL (r = 0.49–0.58, p = 0.001–0.007).
Discussion: In people with MS, the single-leg heel raise test may be clinically useful as it identified impaired muscle performance and differentiated muscle performance from a healthy control group and, together with the control group, correlated with functional mobility.