INTERSEGMENTAL RELATIONSHIPS IN HUMAN LOWER-EXTREMITY SWING MOTIONS

Non-muscular, as well as muscular, forces acting at the knee joint contribute to knee flexion and extension during the swing phase of running. A model was used to predict thigh and shank-foot motion after the knee muscular force was mathematically considered to be zero. The prediction model was not intended to simulate real motion, but rather to quantify non-muscular intersegmental relationships. Comparisons between the observed and predicted motion were made on the basis of kinematic and kinetic parameters. A direct causal relationship was found to exist between the thigh and shank in the predicted motion. Although the non-muscular relationship between proximal and distal segment motion was previously suspected, quantitative evidence has not been available. This type of non-muscular reaction may be critical to the production of maximum speed at the end of a distal segment, with possible application to a wide range of sports skills.