Effect of 12 weeks of Tai Chi training on soleus Hoffmann reflex and control of static posture in older adults
Cartwright, C, Chen, YS & Zhou, S 2011, 'Effect of 12 weeks Tai Chi training on soleus H-reflex and control of static posture in older adults', Archives of Physical Medicine and Rehabilitation, vol. 92, no. 6, pp. 886-891.
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To investigate the effect of 12 weeks of Tai Chi training on soleus (SOL) Hoffmann reflex (H-reflex) modulation and postural control in standing under 4 sensory conditions in older adults.
Experimental research design with pre- and posttraining tests in a training group and a control group.
University biomechanics laboratory.
Community-dwelling older adults (N=34) were assigned to a training (n=20; mean ± SD age, 72.9±4.4y) and a control (n=14; mean ± SD age, 72.9±6.5y) group.
Tai Chi participants attended a 1-hour session of Yang style Tai Chi, 3 sessions a week, for 12 weeks, while control participants maintained their regular daily activities during the same period.
Main Outcome Measures
SOL H-reflex (maximal amplitudes of H-reflex [Hmax] and M-wave [Mmax] waves) and mean displacement of the center of pressure (COP) in the anterior-posterior (COPA-P) and medial-lateral (COPM-L) directions were measured during bipedal standing, with the feet placed on a forceplate and the heels 6cm apart, under 4 sensory conditions: stable surface with eyes open, stable surface with eyes closed, unstable surface with eyes open, and unstable surface with eyes closed.
SOL Hmax/Mmax ratio in the Tai Chi group was upregulated significantly in all 4 sensory tasks after the 12-week Tai Chi training (P<.05). No significant change in COP measurements (mean displacement of COPA-P and COPM-L) was found in either the Tai Chi or control group after the 12-week period.
An increase in SOL Hmax/Mmax ratio during static postural tasks is observed after 12 weeks of Tai Chi training in older adults under all 4 sensory conditions. However, training-induced changes in H-reflex were not accompanied by improvement of performance in the static postural control tasks.