The Kinematic Evaluation of Shoulder and Elbow Joints for Different Walking Speeds

Abstract—The objective of this study was to evaluate the effect of different walking speed on the range of motion, angular velocity, and angular acceleration of the shoulder and elbow during walking. An optical motion capture system was used to capture the walking motion on the treadmill system. The independent variable of this study was set as four levels of walking speeds including 3.6, 5.4, 7.2 km/h, and preferred walking speed. Seven dependent variables were analysed as follows: maximum joint angle, minimum joint angle, range of motion (ROM), maximum joint angular velocity, minimum joint angular velocity, maximum joint angular acceleration and minimum joint angular acceleration. The subject walked according to the randomized walking speed during 90 seconds on the treadmill. Twenty gait cycles of motion capture data from each experiment condition of each subject were extracted. In the shoulder joint, the mean of ROM and the mean of maximum angular acceleration were the highest at 5.4 km/h walking speed. It can be considered that the arm swing was sufficiently performed to maintain the walking stability. At the walking speed 7.4 km/h, the gait pattern of one cycle was too short due to fast walking. It indicated that the time of motion for sufficiently swinging the arm was short. At the walking speed 7.2 km/h, the ROM and angular velocity of the shoulder joint decreased but those of the elbow joint were increased. It could be related to maintain the walking balance by swinging the elbow to compensate the reduction of the shoulder movement during a fast walking. We suggest that the ergonomic threshold walking speed of the wearable robot is limited to 5.4 km/h. In addition, the fast walking speed can cause biomechanical load and discomfort in the arm movement.