The effects of backpack loading on the gait and corresponding compensatory strategy

This study was designed to determine the effect of backpack loading on the gait pattern and corresponding compensatory strategy, which is important to the balance control of biped robot and military training. Five healthy subjects were instructed to walk at their preferred speed on level pathway taking three different loads i.e. 6 kg, 12 kg and 25 kg, on their backs. The results showed that the gait pattern was apparently influenced, and the dominant effects were found to be the flexion of hip, knee joints and pitch angle of torso. The stride speed decreased apparently with loading on their backs, but the stride length showed less changes. Besides, the responses to taking loads might be influenced by the strength of body. An apparent multi-joints coordination motor mode was employed to compensate the influences of loading, however, their contributions are different; hip, knee joints and torso pitch made dominant contributions to the compensation while ankle joints made minor. The anterior pitch of upper torso could be employed to adjust the overall center of mass while loading on their backs, the larger the magnitude of loading on their backs, the larger the anterior pitch angle of torso. After the heel touched the ground, the flexion of hip and knee joints were effective for the shock absorption, which means that the stiffness of hip and knee joints can be used to absorb the shock and avoid the trauma of each joints.