title: Effect of 12 weeks of Tai Chi training on soleus Hoffmann reflex and control of static posture in older adults.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  Experimental research design with pre- and posttraining tests in a training group and a control group.
  
  
  METHODS
  University biomechanics laboratory.
  
  
  METHODS
  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.
  
  
  METHODS
  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.
  
  
  METHODS
  SOL H-reflex (maximal amplitudes of H-reflex [H(max)] and M-wave [M(max)] waves) and mean displacement of the center of pressure (COP) in the anterior-posterior (COP(A-P)) and medial-lateral (COP(M-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.
  
  
  RESULTS
  SOL H(max)/M(max) 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 COP(A-P) and COP(M-L)) was found in either the Tai Chi or control group after the 12-week period.
  
  
  CONCLUSIONS
  An increase in SOL H(max)/M(max) 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.
authors.affiliation: School of Health and Human Sciences, Southern Cross University, Lismore, New South Wales, Australia.
authors.forename: Yung-Sheng
authors.initials: YS
authors.lastname: Chen
authors.forename: Shi
authors.initials: S
authors.lastname: Zhou
authors.forename: Colleen
authors.initials: C
authors.lastname: Cartwright
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D004576:Electromyography; D005260:Female; D006181:H-Reflex / Q000502:physiology*; D006801:Humans; D008297:Male; D004856:Postural Balance / Q000502:physiology; D011434:Proprioception / Q000502:physiology*; D026302:Tai Ji