Measurement of articular angles and ground forces in the sit-to-stand movement

In this paper, two motion protocols are presented that describe the sequence of movements to be complied with by a subject to perform a sit-to-stand movement. In gait analysis, the sit-to-stand movement is the movement a patient does when he/she gets up from a chair and stands in upright position. The protocols are intended to obtain repeatable and reproducible results that can be compared among different studies. The first protocol (standard) is closer to other studies in the literature, in order to improve comparison with previous experimental results. The second protocol (natural) reproduces a sit-to-stand movement more similar to natural conditions. The main differences between the two protocols are in the knee angle, the pose of the arms and the torso at the beginning of the test. The two motion protocols are tested by a volunteer on a gait lab. Results of experimental tests in terms of joint and foot-ground angles, ground reaction force and center of pressure show both the repeatability of the tests and the differences between standard and natural movement during sit-to-stand.