Elevated creatine kinase (CK) levels may be noted in neuromuscular patients as a result of muscle damage and necrosis. We measured the serum CK levels of 62 post-polio patients with chronic neurologic disease (Neuro) and 13 post-polio patients with no evidence of neurologic compromise (Control). Patient groups were comparable for age, gender and years since onset of poliomyelitis. The Neuro group had substantially increased CK levels compared with the Control group, 211 +/- 19.0 IU v 114 +/- 26.2 IU (mean +/- 1 SE; P less than 0.05). Of the Neuro group, 40% had abnormally elevated CK values, compared with 8% of the Control group. Within the Neuro group, there was a robust correlation between elevated CK values and self-reports of strenuous work and level of community ambulation (P less than 0.05). These findings support the hypothesis that chronic muscle overuse may be a contributing factor to the advanced senescence reported by post-polio patients with neuromuscular compromise.