The relation between lower extremity strength and shoulder overuse symptoms: a model based on polio survivors.

OBJECTIVE: To determine the relation between lower extremity weakness and shoulder overuse symptoms among polio survivors. We predicted that individuals with moderate weakness in their leg extensor muscles would use their arms to help compensate for this weakness and would be at high risk for developing symptoms of shoulder overuse. DESIGN: A cohort study of polio survivors recruited from the Einstein-Moss Postpolio Management Program (Philadelphia), the community, and the surrounding region. SETTING: A research laboratory at Moss Rehabilitation Research Institute, Philadelphia, PA. PARTICIPANTS: One hundred ninety-four polio survivors. Demographic and medical history data, symptom data, and strength data were obtained for each. MAIN OUTCOME MEASURES: Presence or absence of shoulder symptoms and ratings of pain by visual analogue scale were recorded. Strength was measured using a hand-held dynamometer and manual muscle testing. RESULTS: Shoulder symptoms could be grouped into two distinct clusters based on the type of testing used for assessment. Symptoms elicited by palpation were present in 26% of the subjects and were strongly related to knee extensor strength and weight. These symptoms were more common among women than men (42% and 10%, respectively). Symptoms elicited by resistance tests were present in 33% of the subjects and were seen with equal frequency in both sexes. These symptoms were also related to lower extremity strength, but the specific relationship was not as clear as for the palpation-related symptoms. CONCLUSIONS: Lower extremity weakness predisposes individuals to shoulder overuse symptoms. Sex and body weight are contributing factors. These results may be generalized to other populations with lower extremity weakness, including the elderly.