Changes in strength over time among polio survivors

Objective: To study changes in the strength of different muscle groups in p olio survivors over a period of approximately 9 months. Design: Longitudinal study. Setting: Moss Rehabilitation Research Institute. Participants: One hundred twenty subjects (57 men, 63 women) were studied o n three occasions, each 3 to 5 months apart. Subjects were recruited throug h the Einstein-Moss Post-Polio Management Program, newspaper advertisements , and polio support groups. Main Outcome Measures: Isometric strength of 30 muscle groups (16 in upper extremities, 14 in lower extremities) was measured, using a hand-held dynam ometer. Results: Data were analyzed in two separate groups: upper-extremity muscles and lower-extremity muscles. Results far the upper-extremity muscles revea led evidence of a significant deterioration in strength. The amount of dete rioration differed among muscles and increased with age. There was also evi dence of deterioration in strength in the flexor muscles in the ankle, hip, and knee. However, the rate of deterioration in these muscles was not stro ngly related to age, time since polio, gender, symptom status, or history o f residual weakness. Conclusions: Strength is deteriorating among polio survivors at a rate high er than that associated with normal aging. This deterioration is not occurr ing in the extensor, or so-called "weight-bearing" muscles, but is occurrin g in many of the upper-extremity muscle groups and in the flexor muscles in the lower extremities.