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Knee and ankle joint forces during steps and jumps down from two different heights
1Kinesiology Research Group, Departments of Anatomy, Physical Medicine and Occupational Medicine, Karolinska Institute and Hospital, Stockholm, Sweden.
Abstract:
Two healthy subjects were filmed on TV-video when performing 14 different steps and jumps from two different heights (0·20 m and 0·43 m) onto two Kistler force platforms that recorded the reaction forces. The ankle and knee load moments and joint forces were calculated using a sagittal plane semi-dynamic biomechanical model. Steps with the ball of the foot from the lower height induced a vertical ground reaction force (Fz) close to 1 body weight (bw) and around 2 bw from the greater height. From the greater height the knee moments for the majority of the step-downs studied were about 100 Nm, which gave knee joint compressive forces of 4-7 bw. The ankle was exposed to loads of similar magnitude but not so much influenced by step height. The reasons why patients with knee pain prefer performing backward step-downs are discussed.
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