Effects of Aging and Tai Chi on Finger-Pointing Toward Stationary and Moving Visual Targets

Kwok JC, Hui-Chan CW, Tsang WW. Effects of aging and Tai Chi on finger-pointing toward stationary and moving visual targets. Arch Phys Med Rehabil 2010;91: 149-55. Objective: To examine the aging effect on speed and accuracy in finger pointing toward stationary and moving visual targets between young and older healthy subjects and whether or not Tai Chi practitioners perform better than healthy older controls in these tasks. Design: Cross-sectional study. Setting: University-based rehabilitation center. Participants: University students (n=30) (aged 24.2 +/- 3.1y), were compared with healthy older control subjects (n=30) (aged 72.3 +/- 7.2y) and experienced (n=31) (mean years of practice, 7.1 +/- 6.5y) Tai Chi practitioners (aged 70.3 +/- 5.9y). Interventions: Not applicable. Main Outcome Measures: Subjects pointed with the index finger of their dominant hand from a fixed starting position on a desk to a visual signal (1.2cm diameter dot) appearing on a display unit, as quickly and as accurately as possible. Outcome measures included (1) reaction time-the time from the appearance of the dot to the onset of the anterior deltoid electromyographic response; (2) movement time-the time from onset of the electromyographic response to touching of the dot; and (3) accuracy-the absolute deviation of the subject's finger-pointing location from center of the dot. Results: Young subjects achieved significantly faster reaction and movement times with significantly better accuracy than older control subjects in all finger-pointing tasks. Tai Chi practitioners attained significantly better accuracy than older controls in pointing to stationary visual signals appearing contralaterally and centrally to their pointing hand. They also demonstrated significantly better accuracy when the target was moving. Accuracy in Tai Chi practitioners was similar to young controls. Conclusions: Eye-hand coordination in finger-pointing declines with age in time and accuracy domains. However, Tai Chi practitioners attained significantly better accuracy than control subjects similar in age, sex, and physical activity level.