Effects of different paces on lower limb dynamics and compensatory mechanisms when elderly fallers cross obstacles
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Abstract:
【Abstract】 Objective To explore the peak moment characteristics of lower limb joints, as well as the contribution rate and compensation mechanism of lower limb joints when elderly people with a history of falls cross obstacles at different paces. Methods The study recruited 30 healthy older adults and 30 elderly fallers. The infrared high-speed motion capture system QUALISYS and the three-dimensional force platform KISTLER were used to obtain the mechanical characteristic data of the elderly when they crossed an obstacle with a height of 15% of their height at three walking speeds of 1.05 m/s, 1.41 m/s, and 1.74 m/s. The data were then modeled and analyzed using Visual 3D software. Results As walking speed increased, the peak knee extension moment, peak ankle plantar flexion moment, and double peak value of hip flexion moment in the healthy group all increased significantly (P<0.05). Compared with the healthy group, the double peak values of hip flexion moment in the fall group were significantly smaller than those in the healthy group (P<0.05). During moderate walking, the contribution rate of the left hip joint in the fall group was significantly higher than that of the healthy group (P=0.025)，while the contribution rate of the ankle joint was significantly lower (P=0.044) .The margin of stability in the front-to-back direction at the moment of ground contact of the stance leg and the stride leg increased with walking speed (P=0.007,P=0.002). Conclusions Compared with healthy elderly individuals, the elderly fallers have lower peak torque, peak ground reaction force, and dynamic stability in the front-to-back direction. As the walking speed increases, the mechanical parameters and the margin of stability increase significantly, and walking stability is improved. Compared with healthy elderly people, elderly fallers usually rely more on the contribution of hip joint movements and reduce the involvement of ankle joints. Based on these results, it is recommended to incorporate fast walking exercises into the daily fall prevention exercise program for the elderly and combine them with coordinated training of the hip, knee, and ankle joints.
