Biomechanical Estimation Method of Internal Loads on Sitting Posture Using a Two-Dimensional Musculo-Skeletal Model

A whole-body musculo-skeletal model in a sagittal plane and an estimation method of internal loads on sitting posture has been developed. Two-dimensional rigid link model was constructed as 13 segments. These segments were connected with elastic springs imitated ligaments or intervertebral discs. Sixty-three muscles were attached on the rigid links. Intra-abdominal pressure was also considered as a balloon. Using the method, muscle forces, ligament tensions, intervertebral loads, and abdominal pressure were calculated from a measured Sitting posture and seat reaction forces. Calculated results were compared with the measurements by intervertebral pressure and EMG. Using this method, the differences of sitting postures or chair conditions could be quantitatively evaluated by internal loads.