Correlation of creatine kinase and gait measurement in the postpolio population.

Measurements of stride length, gait speed, and distance walked during seven days were obtained from 15 postpolio and eight control subjects. Pedometers were used to measure distance walked. Measurements of stride length and speed were performed three times, and there was a high correlation between tests (R = .852-.969). The pedometers failed to record accurately in some postpolio subjects, and these subjects were dropped from analysis when ambulation distance was used as a variable. There were significant differences between the postpolio subjects and controls with respect to gait speed (47.7 +/- 14.0 vs 74.9 +/- 15.9m/min, p less than 0.0005), stride length (55.3 +/- 11.7 vs 69.8 +/- 8.6cm, p = .006), and average kilometers walked per day for seven days (1.97 +/- 1.3 vs 3.89 +/- 1.7, p = .016). The postpolio subjects had their serum creatine kinase (CK) levels measured at the end of the study. Forty percent of subjects had a level above the normal limits of our laboratory. There was a significantly positive correlation between CK levels and the distance walked during the previous 24 hours (R = .75, p = .012). The findings of this study illustrate the impact of gait abnormalities on the ambulatory abilities of the postpolio population. The correlation of CK with ambulation supports the association of exercise as a source of elevated CK levels in the postpolio population.