School of Mechanical Engineering,Tianjin University of Science Technology,Tianjin Key Laboratory of Integrated Design and On-line Monitoring for Light Industry Food Machinery and Equipment
目的 通过分析老年人手提重物及不同步态停止方式下下肢肌肉活动特性及相应关节运动参数的变化,探究手部负重及步态停止方式对老年人步态稳定性以及身体平衡的影响。方法 以不同的负重方式,分别在急停和有计划停止的条件下,采集双侧下肢踝、膝、髋关节角度以及表面肌电信号值。结果 在不同的负重方式下,双侧下肢踝、髋关节角度均有显著差异(p<0.05),而膝关节无显著变化,不同停止方式显著影响各关节角度的变化(P＜0.001)；制动腿胫骨前肌、股外侧肌、股二头肌的平均肌电均表现为急停时肌肉活动水平更高。结论 老年人为应对负重和急停带来的不稳定性,下肢会产生相应的平衡机制。急停时,制动腿胫骨前肌需要更高的肌肉活性来控制踝关节的跖曲角度,从而减小踝关节波动幅度。而单手负重增大了制动腿和尾随腿肌肉做功的差异,导致侧向的不稳定性。实验结果可为老年人加强下肢运动锻炼,增强步态平衡能力,制定负重情景下的安全步态策略,为预防跌倒提供一定的指导。
Objective By analyzing the characteristics of lower extremity muscle activity and the changes of corresponding kinematic parameters of the lower limbs by carrying heavy loads and asynchronous stopping modes, the effects of hand weight bearing and gait stopping modes on the gait stability and body balance of the elderly were explored. Methods Under different load-bearing methods, under the conditions of emergency stop and planned stop, the angles of the ankles, knees, and hips of both lower limbs and the surface EMG signals were collected. Results Under different weight-bearing methods, the angles of both lower limbs ankle and hip joints were significantly different (p <0.05), while the knee joints did not change significantly, and the different stopping methods significantly affected the changes of each joint angle (P <0.001); The average myoelectricity of the leg tibia anterior muscle, lateral femoral muscle, and biceps femoris showed higher muscle activity during emergency stop. Conclusions In order to cope with the instability caused by weight-bearing and emergency stop, the elderly will have a corresponding balance mechanism in the lower limbs. During an emergency stop, braking the tibialis anterior muscle of the leg requires higher muscle activity to control the flexion angle of the ankle joint, thereby reducing the amplitude of the ankle joint fluctuation. The one-handed load increases the difference in work done between the braking leg and the trailing leg muscles, resulting in lateral instability. The experimental results can provide some guidance for the elderly to strengthen lower limb exercise, enhance gait balance ability, formulate safe gait strategies in weight-bearing situations, and prevent falls.