Thursday, October 14, 2010

Tai Chi Chih Acutely Decreases Sympathetic Nervous System Activity in Older Adults

A study published in the Journals of Gerontology studied the effects of doing Tai Chi  on the sympathetic nervous system (SNS) of healthy older adults. Significant changes were described in the Tai Chi group vs. the Health Education group, and furthermore vs. a second group performing guided stretching that was not Tai Chi.

"Tai Chi has been described as “meditation through movement” and can be characterized as consisting of a series of prescribed slow, purposeful movements with an emphasis on concentration and relaxation. Besides behavioral and self-report measures, few studies have carefully examined physiological pathways affected by Tai Chi. Our findings support the hypothesis that TCC promotes decreased SNS activity, although changes in blood pressure or heart rate were not found, possibly due to short duration of TCC practice assessment. The mechanisms accounting for the changes in PEP are unclear. Subsample analyses that explored the effects of slow physical movement indicated that such activity is not sufficient to alter PEP. We speculate that TCC may alter sympathetic activity in the short term via other mechanisms such as relaxation and/or meditation. 

Background. Aging is associated with increases of sympathetic nervous system activation implicated in the onset of hypertension and cardiovascular disease. The purpose of this study was to examine whether the practice of Tai Chi Chih (TCC), a movement-based relaxation practice, would acutely promote decreases of sympathetic activity in elderly persons. 
Method. The sample included two groups of older men and women (age ≥ 60 years): TCC practitioners (nnn = 8) returned for a second evaluation and performed videotape-guided stretching for 20 minutes to evaluate the effects of slow-moving physical activity on sympathetic activity.   = 19) and TCC-naïve participants ( = 13). Participants were recruited after completing a 25-week randomized trial of TCC or health education. TCC practitioners performed TCC for 20 minutes, and TCC-naïve participants passively rested. Preejection period, blood pressure, and heart rate were measured before and after the task. A subsample (
Results. Results showed that TCC performance significantly decreased sympathetic activity as indexed by preejection period (p =.01). In contrast, there was no change in preejection period following passive rest or slow-moving physical activity. Neither blood pressure nor heart rate changed after TCC performance.
Discussion. This study is the first to our knowledge to assess the acute effects of TCC practice on sympathetic activity in older adults. TCC performance led to acute decreases in sympathetic activity, which could not be explained by physical activity alone. Further study is needed to determine whether the acute salutary effects of TCC on autonomic functioning are sustained with ongoing practice in older adults."

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