Muscle strength in patients with chronic pain.

OBJECTIVE To analyse the influence of chronic pain on muscle strength. DESIGN Muscle strength of patients with unilateral nonspecific chronic pain, in an upper or lower limb, were measured according to a standardized protocol using a hand-held dynamometer. Before and after muscle strength measurement, a visual analogue scale for pain intensity was assessed. RESULTS Forty patients were measured and the muscle strength of the painful side was 20-30% less than that of the nonpainful side. Strength reduction was seen in the whole limb. A significant correlation between pain intensity and reduced muscle strength in the painful limb existed for hip flexion, knee flexion, knee extension and three-point grip. CONCLUSIONS A strength reduction of 20-30% in a painful limb seems to be 'normal' in chronic pain patients.