Can Tai Chi improve the balance control of elderly persons with visual impairment?

Abstract

Introduction: Good balance is essential for controlling body movement, but it shows significant changes with age when vision is impaired. In addition, fear of falling increases with age and is associated with visual function. Regular exercise produces the same physiological and psychological benefits in the visually impaired as in others, but the visually impaired are usually less physically active, and therefore experience reduced physical functioning and well-being. Tai Chi has been suggested as a suitable form of exercise for those with visual impairment. Its benefits for balance control, muscle strength and preventing falls have been proven in studies with sighted elderly subjects. This study examined whether or not balance control in the elderly differs with varying degrees of visual impairment and to what extent Tai Chi training might affect the balance control of elderly persons with visual impairment. Methods: The investigation included a cross-sectional samples study comparing balance control between sighted, low vision, and blind subjects. A randomized clinical trial investigated the effect of Tai Chi on the balance control of elderly persons with visual impairment. The participants underwent the following assessments: 1) a passive knee joint repositioning test; 2) a sensory organization test (SOT); 3) muscle strength assessment; 4) a perturbed double-leg stance test (PDLST); 5) the standard five-times-sit-to-stand test (FTSTST); and 6) evaluation with the Falls Efficacy Scale International (FES-I). For the randomized clinical trial, 40 visually impaired elderly persons were randomly divided into a Tai Chi group and a control group. Both groups attended three, 1.5 hour training sessions per week for 16 weeks. Assessments were performed before and after the training. Results: Compared with the low vision subjects, the sighted elderly achieved higher average peak torque-to-body weight ratios in concentric knee extension. In the SOT, the sighted elderly showed less body sway than the others in conditions where visual inputs could help them maintain standing balance. The sighted and low vision subjects showed less body sway during forward and backward translations of their support surface than the blind. The sighted elderly also reported less fear of falling than those with poor vision. The Tai Chi trainees showed improvements in balance control after training. They had significant average improvements in knee proprioception, and in the SOT they achieved significant improvements in their visual and vestibular ratios compared to the control group. In the PDLST, the Tai Chi group swayed less than the control group during forward platform perturbations with the eyes closed. Conclusions: Low vision and blind elderly persons have poorer balance control than the sighted elderly. Vision plays an important role for very old adults in controlling balance in challenging balance control circumstances. Tai Chi can improve balance control in the visually impaired elderly. They had better knee proprioception and improved balance control when there was an increased reliance on the visual and vestibular systems during stance after 16 weeks of training.