Muscle strength and stiffness of elbow muscles: correlation with upper limb motor functions in people with chronic stroke.

The study used a cross-sectional design, so it cannot determine if strength changes cause functional changes or vice versa. Muscle stiffness was measured at rest, which may not reflect stiffness during active movement or functional tasks. The stroke participants were recruited from a self-help group, which may mean they were more active and independent than the general stroke population. Hand-held dynamometry was not validated for upper limb strength in people with stroke, and myotonometry can be influenced by subcutaneous fat thickness. The sample size was moderate, and sex differences were present in both groups, which may affect muscle strength and stiffness results.

The authors declared no conflicts of interest. The work was supported by research funding from the Research Centre for Chinese Medicine Innovation of The Hong Kong Polytechnic University.

Do not assume that reducing muscle stiffness will improve upper limb function. This study found that resting muscle stiffness had weak or inconsistent correlations with motor function and activity scores, whereas muscle strength showed stronger links. Targeting stiffness may not yield the same functional gains as targeting strength.