Age-Related Difference In The Relationship Between Lower-Limb Joint Proprioception And Body Dynamic Stability

With the acceleration of the aging process,the number and proportion of the elderly have increased year by year.The health problems about elder have become a research hotspot.Fall is one of the most common factors that cause the elder to be injured or die,and always associated with the ability to control body balance.Therefore,studying body balance ability can help us deeply understand about falls,and it is also very meaningful for fall risk assessment and fall prevention.Proprioception is one of the three important physiological factors affecting the body balance.This study will focus on the lower extremity joint proprioception that is more related to daily activities,and the proprioception is measured by the lower joint position sense.In addition,since most of the falls occur during the walking process,it is a reliable method to evaluate the fall risk based on the gait characteristics.This study uses the basic parameters of gait and local dynamic stability to quantify the balance ability of the human body.Aiming at exploring the relationship between the lower-limb proprioception and body dynamic stability during walking.And the contributions of the lower-limb joint proprioception to balance ability need to be better revealed.72 healthy subjects are recruited in this study,including 36 young people between the ages of 18-30 and 36 middle-aged people between the ages of 50-60.Each subject completed two parts of the experimental procedure.One was passive positioning and active repositioning of the hip,knee and ankle positions,and the other part was walking on the treadmill at preferred speed.The lower-limb joint proprioception is assessed by the joint position sensory error.Body dynamic stability is measured by gait parameters,center of pressure parameters,and local dynamic stability.Raw data acquisition was performed using a constant velocity dynamometer,VICON motion capture system,and a treadmill with Kistler force plate embedded in it.The calculation and statistical analysis of the data yielded the following conclusions:(1)The joint position sense errors of the middle-aged are significantly increased compared with the young people,indicating that the lower-limb joint proprioception of middle-aged declines.The average length of stride and step length during walking is significantly lower than that of young people,but the variability is higher than that of young.In addition,the value of COP length in anterior-posterior is smaller than young,indicating that the middle-aged people walk more unsteadily.The maximum Lyapunov exponent of the acceleration,velocity and hip angle position of middle-aged people is significantly higher than that of young people,indicating that the local dynamic stability of body during walking is worse in middle-aged,and the risk of fall is higher than that of young.(2)The hip joint positon sense error in young people has a significant positive correlation with the local dynamic stability of the center of gravity in the vertical direction.It shows that the hip proprioception is associated with the resistance of the center of gravity to perturbations.Young with worse hip proprioception have worse ability to control the body’s undulating motion and the higher risk of falling.(3)There is a significant correlation between the hip joint sense error and the stride length,step length,center of pressure trajectory range in the anteroposterior direction in middle-aged people.It shows that hip proprioception has a relationship with the walking strategy in the middle-aged people.Middle-aged people with poor hip proprioception take shorter step,and the inclination of their body during walking is smaller.(4)The relationship between hip proprioception and body dynamic stability in young and middle-aged people is different,indicating that hip plays different role in different populations.In the young people,the decline in hip proprioception does not affect the basic gait characteristics,but has relation to the balance of COM control and risk of falling.In middle-aged people,the hip proprioception is related to the walking strategy and body sway in anterior-posterior,but does not affect the local dynamic stability.Whatever,the hip is more closely related to the posture balance control comparing to knee and ankle.Enhancing the hip proprioception may have a better effect on reducing the risk of falls.