The Bent Hip and Bent Knee Gait and its Possible Role in the Evolution of Modern Human Bipedalism

Abstract

The relatively stiff gait of modern humans minimizes the muscular work done to move the lower limbs and the center of mass. Nonhuman primates, and perhaps our earliest ancestors, use a form of bipedalism in which the hip and knee are held in a flexed position. This thesis follows up on other studies examining loading and energetic costs of these compliant walking gaits by examining the effects of increased hip and knee flexion on kinetic, kinematic, and energy exchange variables. The bipedal gait of twelve human subjects using normal and bent hip and bent knee gait were compared. The subjects walked along force plates embedded in the ground while 3D kinematic data was simultaneously gathered. The data was then processed using EvaRT, Orthotrak, and Matlab to evaluate the variables used. During the bent hip and bent knee bipedal locomotion subjects demonstrated lower peak vertical and parallel ground reaction forces, much higher ankle flexion, less hip extension, and less energy recovery during a full stride. These data provide novel insight into the nature and costs of locomotion in bipedal primates and the earliest human ancestors.