Pre-landing control of angular and linear momenta after tripping during gait.

抄録

This study aimed to characterize basic postural recovery responses in younger adults before the first forward step landing (FL) after tripping in gait, or the pre-landing phase. Twelve young participants were tripped while walking and were required to return to normal walking after tripping. We recorded the kinematics and kinetics of their recovery responses using a 17-camera motion capture system and a force platform. We compared the whole-body angular momentum (WBAM) around the whole-body center of mass (WBCM) and the whole-body linear momentum (WBLM) in the tripping trials, with those in the normal walking trials. We also examined the angular momentum (AM) and linear momentum (LM) of the body segment groups and the joint torques. The forward WBAM around the WBCM increased by tripping started decreasing early in the pre-landing phase. When the forward WBAM decreased in the tripping trials, the backward AM of the tripped leg increased, while the increase in the forward AM of the head-neck plus trunk (HT) and support leg was suppressed. There was no significant difference in the forward WBAM around the WBCM at FL between the tripping trials and the normal walking trials. On the other hand, the forward and downward WBLM at FL were 1.1 and 2.5 times larger in the tripping trials than in the normal walking trials, respectively. In addition, all of the forward AM and the forward and downward LM of the HT at FL were significantly larger in the tripping trials. These results indicated that younger adults could decrease the forward WBAM increased by tripping to a level comparable to that at FL of normal walking. It is suggested that suppressing the increase in the forward angular velocity of the HT and support leg during a rapid forward swing of the tripped leg contributes to decreasing the forward WBAM around the WBCM. It is also suggested that although the WBAM changed due to tripping can be controlled during the pre-landing phase, suppressing the forward and downward WBLM as well as controlling the AM and LM of the HT after FL would be required for recovering to normal walking.