Effect of tai chi on eye-hand coordination in the older adults

Abstract

Eye-hand coordination is an important function required in many daily activities. However, motor control is known to decline with aging which could affect finger-pointing tasks. The requirement for coordinating eye and hand movements with movements of the trunk and lower extremities during repeated Tai Chi practice may have also improved the practitioners' eye-hand coordination. Moreover, eye-hand coordination demands temporal, spatial, and often cognitive processing in daily activities that require the registration of visual signals in finger-pointing tasks involving choice. Tai Chi is a mind-body exercise, previous studies have demonstrated that experienced Tai Chi practitioners showed better attention and memory than did the older controls. University students, older subject controls and experienced Tai Chi practitioners participated in this cross-sectional study. The subjects performed rapid index finger-pointing using their dominant hand, from a fixed starting position on a desk to a 1.2cm circle that appeared on a visual display unit. The task was to touch the circle as quickly and as accurately as possible in 3 testing protocols: (1) A single visual signal appeared randomly. (2) A visual signal moved horizontally from left to right. (3) A choice test paradigm. Outcome measures included reaction time, movement time, accuracy and the number of wrong movements. Static visual signal The young university students achieved faster reaction and movement times, and greater accuracy significantly than the older control subjects. Tai Chi practitioners showed significantly better accuracy than the older controls at the signal contra-laterally and centrally. Their accuracy was also similar to that of the young subjects. Moving visual signal The students achieved significantly better outcome measures than the older controls. Although the Tai Chi practitioners only tended to have faster but not statistically significant reaction time than the older control subjects, they showed significantly better accuracy than the older controls, which was comparable to that of the younger students. Finger-pointing with a cognitive component The students achieved significantly better outcome measures and fewer wrong movements than the older control subjects. The Tai Chi practitioners had significantly faster movement times than the control subjects, attained significantly better accuracy and made fewer wrong movements. Their accuracy and number of wrong movements were similar to those of the young students. These results demonstrate that, with aging, a decline in eye-hand coordination occurs in finger-pointing tasks toward static and moving visual signals. This is also true of tasks that require cognitive processing in a choice paradigm. However, Tai Chi practitioners had achieved significantly better accuracy. Tai Chi emphasizes exact joint positioning and precise movement control. It may be that better joint proprioception and control of arm trajectory in Tai Chi practitioners have enhanced their accuracy in finger-pointing tasks - even to the level of healthy young subjects. The finding of fewer wrong movements in Tai Chi practitioners may be due to their better attention in the signal encoding process and to their better registration of the visual signal in the memory retrieval process, both of which have been shown in our previous study.