| Objective: Taking Taijiquan as an intervention means,by testing the lower limb dynamics,walking ability and dynamic balance ability of subjects in different stages of Taijiquan practice,this paper analyzes the influence of Taijiquan practice time on the intervention effect of Taijiquan,and expounds the change law and significance of relevant parameters of lower limb dynamics and dynamic balance ability of the elderly in different stages of practice,In order to provide reasonable suggestions for the elderly to participate in Taijiquan practice.Methods: 35 qualified subjects recruited by the Institute were randomly divided into experimental group(18 persons)and control group(17 persons).The subjects in the Tai Chi group were trained for 6 months(the elderly in the experimental group participated in training 4 times a week for 1 hour each time,including 5 minutes of warm-up preparation,50 minutes of Taijiquan practice and 5 minutes of finishing activities),During this period,the elderly in the control group will be required to follow the previous rhythm of life without motor intervention of any lower limb system.The subjects’ lower limb dynamics,kinematics,plantar pressure distribution,walking ability and balance index were collected before training,6 weeks of training,12 weeks of training,18 weeks of training,24 weeks of training and 6 weeks after training.The joint torque(N · m),lower limb / joint stiffness,joint work(J / kg),lower limb load rate(%),peak pressure in each area(N)Step length(m),step speed(M / s),total gait cycle time(s),left and right single support time(s),left and right maximum support force(n),Berg balance scale test score,cop-y AXIS lateral maximum displacement(m),cop-y AXIS lateral displacement average velocity(m / s),etc.Results: 1)Lower limb dynamics: There was no significant change in hip stiffness of Tai Chi group before training(0.015 ± 0.004),at each stage of training(0.016 ± 0.002 at 6 weeks,0.017 ± 0.003 at 12 weeks,0.015±0.003 at 18 weeks,0.014 ± 0.002 at 24 weeks),and at 6 weeks after stopping training(0.015 ± 0.004),P values were 0.568,0.582,0.331,0.595 and 0.684,respectively.The stiffness of knee and ankle joints at 12 weeks of training(knee joint 0.053 ± 0.001)and 6 weeks of training(ankle joint 0.066 ± 0.002)was higher than that before training(knee joint 0.041 ± 0.001 and ankle joint 0.057 ± 0.00)(P = 0.009,P =0.036).However,6 weeks after discontinuation of training(knee joint 0.046 ± 0.002,ankle joint 0.084 ± 0.005)were significantly lower than 24 weeks after training(knee joint 0.070 ± 0.005,ankle joint 0.069 ± 0.004)(P = 0.004,P = 0.017).The peak hip joint torque at 6 weeks after training(1.036 ± 0.247)was significantly higher than that before training(0.848 ± 0.085)(P=0.007),and it decreased to the level at 18 weeks after training(1.187 ± 0.237)(P = 0.104)at 6 weeks after stopping training(1.178 ± 0.142).At 12 weeks of training(0.691 ± 0.028),the peak torque of knee joint was significantly higher than that before training(0.650 ± 0.031)(P = 0.008),and decreased to the level before training at 6 weeks after stopping training(0.657 ± 0.024)(P = 0.642);the peak ankle torque at 6 weeks after training(1.101 ± 0.013)was significantly higher than that before training(1.039 ± 0.034)(P = 0.015),and decreased to 12 weeks after training(1.172 ± 0.022)(P = 0.122).The energy absorption of lower limb joints in Tai Chi group increased with the extension of training time.The hip joint was the main joint of energy absorption,and the ankle joint was the weakest.The average load rate of lower limbs in Tai Chi group had an intervention effect at 18 weeks of training(32.44 ± 1.04 at 18 weeks,20.63 ± 0.78 before training,P = 0.014),and the maximum load rate of subjects at 6 weeks of training(35.80 ± 0.79 at 6 weeks,32.51 ± 1.45 before training,P = 0.029).The intervention effect at 6 weeks after stopping training was lower than that at 24 weeks of training(24.21 ± 0.68,40.42 ± 0.57,P = 0.008,P = 0.026).2)Walking ability: after 12 weeks of training,the time taken by subjects in the Tai Chi Group for 10 meter timed walking(7.96±0.72)and timed standing walking(8.28±0.95)decreased compared with that before training(8.58±0.99 and 8.83±0.83),P=0.008,P=0.031,and reached the best result at 18 weeks of training(7.21±0.58 for 10 meter walking and 7.91±0,82 for standing walking),which remained good after stopping training(10 meter walk 7.37±0.70,stand up walk 8.16±0.69)(P=0.635,P=0.1760);each stage of training had no effect on the basic gait characteristics of subjects in Taiji group,and the test P values of main effect and interaction effect were > 0.05.3)Peak plantar pressure distribution: there was no significant difference between the two groups before training.After 12 weeks of training,the peak plantar pressure in the Tai Chi group was significantly higher than that in the control group(P < 0.05),and the area from heel to middle foot was symmetrical;After 18 weeks of training,the t2-5 area of the left and right feet in the Tai Chi group was smaller than that in the control group,and the other areas were significantly larger than those in the control group and the Tai Chi group before training(P < 0.05),and the pressure distribution of both feet was consistent;There was no significant difference in the distribution of peak plantar pressure and the consistency of both feet in the Tai Chi group after 24 weeks of training and 6 weeks after stopping training compared with 18 weeks of training(P > 0.05).It could also be maintained well after stopping training,and the intervention effect was not easy to disappear.4)The dynamic stability of body posture : the maximum displacement of COP-y on the left and right sides of the two groups before training(0.20 ± 0.05 on the left side of the Taiji group and 0.18 ± 0.03 on the left side of the control group,P = 0.437);the right side of the Taiji group was 0.12 ± 0.04,the right side of the control group was 0.11 ± 0.03,P = 0.859)and the average velocity of displacement(the left side of the Taiji group was 0.62 ± 0.16,the left side of the control group was 0.64 ± 0.21,P = 0.092).There was no significant difference between the right side of the Taiji group(0.62 ± 0.16)and the right side of the control group(0.36 ± 0.15)(P = 0.760).After 12 weeks of training,the maximum displacement deviation of left foot(0.10 ± 0.02)and the average displacement velocity of left and right foot(0.43 ± 0.14 of left foot and 0.29 ± 0.01 of right foot)in the Taiji group were significantly lower than those before training(P values were 0.005,0.006 and 0.031,respectively).After 18 weeks of training,the maximum displacement deviation on the right side(0.07 ± 0.02)decreased compared with that before training(P = 0.005),the body shaking amplitude decreased,and the body posture was gradually symmetrical.Although 24 weeks of training could not achieve absolute symmetry,the intervention effect was well maintained after 6 weeks of training.Conclusion: 1)Tai Chi exercises can increase the stability of the ankle joint in a short time,and the intervention effect on the stability of the knee joint is slightly longer than that of the anklejoint,and the intervention effect disappears quickly after stopping training.2)At the beginning of Tai Chi exercise,the intervention effect of hip and ankle joint strength is better than that of knee joint,and the knee joint strength decreases fastest.After 24 weeks of exercise,the subjects ’ energy absorption capacity of lower limbs and ability to withstand external load significantly increased,but the training effect decreased with the extension of time.3)Although short-term Tai Chi intervention fails to change the basic gait characteristics of the subjects,it can increase their walking speed to a certain extent and improve the walking ability of the elderly.4)Subjects need to practice for at least 12 weeks to improve their dynamic balance ability,and the intervention effect remains good after stopping training. |
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