Relationship between quadriceps strength and rate of loading during gait in women.

One function of skeletal muscle is to serve as the body's shock absorbers and thus dampen rates of loading during activity. The aim of this cross-sectional study was to determine the significance of muscle strength on rates of loading during gait. Thirty-seven women (mean age: 34.5 +/- 8.2 years) were solicited by advertisement and placed into one of two groups-strength-trained or sedentary-on the basis of training history. They walked (10 trials) over a 10-m walkway at a controlled speed of 1.22-1.35 m/s while the rate of loading was sampled with a 1,000-Hz force platform. Quadriceps and hamstring strength was measured at 90 degrees/s with an isokinetic dynamometer. Statistical analyses (p < 0.05) included descriptive statistics and unpaired t tests for comparison between groups. The women in the sedentary group weighed more and had significantly less concentric and eccentric strength of the quadriceps and hamstrings relative to body weight than did those in the strength-trained group. In addition, they demonstrated significantly higher rates of loading (2.21 +/- 0.15 compared with 1.75 +/- 0.08%wt/ms) than those in the strength-trained group.