Kinematic and kinetic comparison of downhill and level walking.

Kinematic and kinetic data were collected from 12 healthy subjects whilst they performed both downhill and level walking at a controlled cadence. A ramp of 6 m length and a gradient of -19% was used for downhill walking and this incorporated the same force platform that was used for level walking. Planar net joint moments and mechanical power at the ankle, knee, and hip joints were calculated for the sagittal view using force platform and video records based on standard inverse dynamics procedures. On the basis of differences in ankle, knee, and hip joint kinematics the ankle joint was seen to compensate for the gradient at push off and during the swing, the knee joint from early stance through until early swing phase, and the hip joint from early swing through until the early stance phase. The major differences in joint moments and muscle mechanical power were seen in the knee and ankle joint. Whereas peak moments and muscle power were much higher for downhill walking in the knee joint, these measures were significantly smaller at the ankle joint. Hip joint moments and muscle power estimates were only slightly larger for downhill walking. These data explain well the problems that patients with patellofemoral pathology and anterior cruciate ligament (ACL) deficiency encounter with downhill walking, and the muscle soreness experienced by mountain trekkers. RELEVANCE: Biomechanical estimates of musculoskeletal loadings in gait are invariably derived from laboratory studies of walking over a level surface. In this study comparisons were made between downhill and level walking in order to appreciate more fully the increased loadings on the lower extremity under more stressful but not atypical conditions. The data so derived provide the necessary basis for the prediction of loadings on specific muscle/joint structures and can serve as a foundation for exercise prescription with patients recovering from injury or orthopaedic surgery.