Effect Of External Force Perturbations On Upright Posture Stability In Healthy Adults Of Different Ages

Objective:To analyze the influence of external force interference on the stability of upright posture,and its influencing factors;A preliminary attempt was made to establish clinical reference values for people with different basic conditions.Methods:one hundred and twenty healthy participants were recruited in the rehabilitation medical center of a third class hospital in Beijing,including 55 males and 65 females.They were divided into youth group(18-44 years old),middle-aged group(45-59 years old)and elderly group(60 years old and above),each group had 40 participants.After recording the basic data,the external force interference test was carried out with the same force in the front,behind,left and right directions,the kinematic data was measured by attitude sensor.The Multidirectional Reach Test(MDRT)and the Timed Up and Go Test(TUG)were performed at the same time.Thirty participants were selected for the test-retest reliability test of Jerk value detected by attitude sensor,and the interval was 2 weeks.Results:(1)External force interference significantly affected the stability of standing posture(P﹤0.01),the Jerk value generated by the external force interference in the front and behind directions(6.619±2.691,7.263±2.965)was significantly greater than that generated by the interference in the left and right directions(4.755±1.890,4.947±2.073),and the difference is significant(P﹤0.01).Although there was no significant difference in the value of Jerk between the anterior and posterior directions(P﹥0.05),but Jerk P was larger than Jerk A.(2)Age and gender were important factors affecting the stability of standing posture under external interference(P﹤0.01).The Jerk value increased with age,and the Jerk value of elderly group >that of middle-aged group > that of young group(P < 0.01).The Jerk value of men was less than that of women,and there was significant difference(P﹤0.05).BMI and physical activity level had no significant effect on the stability of upright posture after external force interference(P﹥0.05).(3)The ICC of the Jerk value after interference in four directions ranged from 0.863 to 0.988.There was a significant negative correlation between Jerk value and MDRT(P﹤0.01),and there was a significant positive correlation between Jerk value and TUG.Conclusion:1.External force interference have a significant impact on the stability of human upright posture,the influence of external force on the stability of human body in front and back direction is greater than that in left and right direction,and the influence of external force backward on the stability may be greater than that of external force forward.2.Age and gender have significant effects on the stability of upright posture,the stability of upright posture decreased with age,the posture stability of men is better than that of women,however,it was not found that BMI and physical activity level have significant effects on the stability of upright posture.3.Using the acceleration change rate index of attitude sensor to detect the stability of upright posture under external force interference has good reliability,it can be used as a quantitative method to evaluate the stability of upright posture.