Kinematic characteristics of gait in middle-aged adults during level walking.

Middle-aged people have shown a high fall incidence and degeneration in gait stability, while few studies concern that. This study aimed to assess the kinematic characteristics of gait in middle-aged people compared with younger and older ones during level walking, and to find sensitive indicators to characterize degenerated gait stability in middle-aged people. 13 middle-aged (mean age=52.1 years), with 13 older (mean age=74.8 years) and 13 young (mean age=23.3 years) healthy adults participated in this study. We assessed following gait parameters of the subjects during their level walking: 1) temporal-spatial gait parameters: normalized gait velocity, stride length, step length and their variability; 2) gait stability parameters: acceleration root mean square (RMS) of COM and its variability; and instantaneous COM-COP inclination angles. Compared with young and older subjects, middle-aged adults showed no significant difference in temporal-spatial gait parameters and their stride-to-stride variability (P>0.050); Compared with young subjects, middle-aged adults showed a significant higher value in medial-lateral (ML) direction of acceleration RMS of COM (P=0.038) and its stride-to-stride variability (P=0.030), as well as in COM-COP inclination angle (P=0.003). There was no significant difference in the above two parameters of gait stability between middle-aged and older subjects (P>0.050). Results illustrated that middle-aged subjects showed similar degenerated pattern in gait stability as the older ones in ML direction. Gait stability parameters, including ML acceleration of COM and its variability, as well as ML COM-COP inclination angle may help to characterize this degenerated gait stability. It's necessary for us to develop early interventions for middle-aged adults to prevent falls during walking.