The Effects Of Tai Chi Exercise On Body Stability Among The Elderly During Stair Walking

Objectives: Ascending and Descending stair is high fall risk activity among the elderly.The decrease of illumination and adding an synchronized cognitive task will add the fall risk.Tai Chi is a body-mind activity,it is still unknow that where Tai Chi could improve body stability during stair ascent and descent under different illumination or under different cognitive condition.Through two separate experiments,our research aimed to investigate the effect of Tai Chi on body stability under two conditions,1.Different illumination levels,2.Different cognitive conditions,and analyze the effect of Tai Chi exercise on gait,body control and stability during stair walking.Methods: Experiment 1: Forty-five healthy elderly women were divided into three groups,namely,Tai Chi exercise group,brisk walking group,and no-exercise control group.Under high and low illumination levels,all the participants ascended and descended a staircase,during which force platforms and a motion capture system collected the data.Exepriment 2: Fifteen healthy,elderly persons who regularly exercised TC and fifteen gender matched control participants in our study.They were asked to walking ascent and descent the stairs under cognitive and no cognitive conditions.Vicon motion analysis system and Kistler force plates were used synchronously to collect data.Results: Stair ascent under different levels of illuminations: Under the high illumination,Tai Chi exercise participants exhibited higher loading rate and anteroposterior center of pressure(COPap)displacement as well as a lower braking impulse than no-exercise group.Under the low illumination,Tai Chi exercise participants demonstrated higher COPap and mediolateral center of pressure(COPml)displacements as well as lower braking and lateral impulses compared with no-exercise participants.The center of mass(COM)ml sway in Tai Chi and no exercise participants were higher,the loading rates in Tai Chi and walking participants were higher,and the lateral impulse in no exercise participants was higher under low illumination than under high illumination.Tai Chi participants increased their foot clearance,head inclination angle,and COPap displacement under low illumination.Stair descent under different levels of illuminations: Tai Chi participants decreased horizontal velocity,COM sway,and increased foot clearance compared with other participants;Compared with under high illumination,Tai Chi participants decreased horizontal velocity,loading rate,braking impulse,and increased inclination angle,COM sway,center of pressure displacement under low illumination.Stair ascent under different cognitive tasks: Compared with NE participants,TC participants had a lower head inclination angle,trunk inclination angle,hip angle,laterial impulse and COM-COPap/ml separation,a higher ankle angle and loading rate under cognitive task condition;TC participants had a lower head inclination angle,trunk inclination angle,higher ankle angle,loading rate and COM-COPml separationunder no cognitive task condition.Compared with under no cognitive task condition,TC participants increased foot clearance,NE participants increased their laterial impulse and COM-COPml separation under cognitive task condition.Under cognitive task condition,body stability decreased among NE participants,while TC participants remained unchanged.Stair descent under different cognitive tasks: Compared with NE participants,TC participants had a lower horizontal velocity,head inclination angle,trunk inclination angle,hip angle,lateral GRF and COM-COP seperation,a higher foot cleariance and ankle angle under cognitive task condition;TC participants had a lower trunk inclination angle,higher ankle angle,posteiral GRF and COM-COPml seperation under no cognitive task condition.Compared with under no cognitive task condition,TC participants increased laterial GRF,COM-COPap seperation,NE participants increased their COM-COPml separation under cognitive task condition.Conclusions: Both the decreased illumination,or a synchronized cognitive task will decrease body stability during stair walking among the elderly.Tai Chi could increase body stability during stair ascending and descending under normal condition,low illumination condition or synchronized cognitive task condition.As a result,it is recommended that the elderly should do regular and long-term Tai Chi exercise to prevent fall during stair walking.