To investigate the patterns of gait and locomotion in three dimension space using OptiTrack motion capture system in 30 healthy people aged 20-70 years.

The 3D OptiTrack motion capture system was applied in young(aged 20-30 years, n=10), middle-aged(aged 40-50 years, n=10)and the elderly(aged 60-70 years, n=10)to capture the gait and the rhythmic oscillations of the trunk, head, hip and kneewhen subjects walked on the treadmill under three different conditions of normal walking, walking under visual interfering and walking under proprioceptive interfering.Several markers were placed on the subject.For each locomotor trial, the preferred walking speed, stride width, stride time, the absolute angular dispersions and the stander deviation of four segments around the roll, pitch and yaw axes, and gait instability(λ)were calculated to assess the equilibrium strategies of head, trunk, pelvis and knee under different experimental conditions.

With increasing age, there were decreases in preferring walking speed(PWS)and increases in stride width(F=3.23, 3.87; P=0.030, 0.020, respectively). The absolute angle of the segment of head in roll axis was significantly smaller in young group than in middle age and elderly group(F=4.01, 3.72; P=0.035, 0.028, respectively)under the condition of normal walking and proprioceptive interfering.The trunk sway in yaw was significantly decreased while significantly increased in roll plane either in normal walking or walking under proprioception interfering(F=3.19, P=0.015). The standard deviation(SD)of movement of head, trunk and hip in yaw direction was higher in young group than in middle-age and elderly group(F=2.89, 3.14, 3.92; P=0.036, 0.019, 0.034, respectively), but was lower in young group in roll direction than in middle-age and elderly group(F=3.90, 2.56, 3.28; P=0.017, 0.021, 0.056, respectively), the difference existed only in hip and trunk under proprioception interfering.The SD value of movement of bilateral knee joints was increased in elderly subjects.Using mediolateral-λ(ML-λ)to predict the gait stability, the results showed a significantly increased λ value by our small circle, and the λ value was positively correlated with age(r=0.03, P<0.05).

With aging, the abnormal adjustment of body posture and the incongruity of gait may cause a high risk for falling, and gait instability begins to increase as early as age 40-50 years.This finding supports that local dynamic stability is likely to be an indicator of falling risk.OptiTrack motion capture system can be used to evaluate a balance for rehabilitation.

Gait; Musculoskeletal equilibrium