title: Tai Chi Training may Reduce Dual Task Gait Variability, a Potential Mediator of Fall Risk, in Healthy Older Adults: Cross-Sectional and Randomized Trial Studies.
abstract: BACKGROUND
  Tai Chi (TC) exercise improves balance and reduces falls in older, health-impaired adults. TC's impact on dual task (DT) gait parameters predictive of falls, especially in healthy active older adults, however, is unknown.
  
  
  OBJECTIVE
  To compare differences in usual and DT gait between long-term TC-expert practitioners and age-/gender-matched TC-naïve adults, and to determine the effects of short-term TC training on gait in healthy, non-sedentary older adults.
  
  
  METHODS
  A cross-sectional study compared gait in healthy TC-naïve and TC-expert (24.5 ± 12 years experience) older adults. TC-naïve adults then completed a 6-month, two-arm, wait-list randomized clinical trial of TC training. Gait speed and stride time variability (Coefficient of Variation %) were assessed during 90 s trials of undisturbed and cognitive DT (serial subtractions) conditions.
  
  
  RESULTS
  During DT, gait speed decreased (p < 0.003) and stride time variability increased (p < 0.004) in all groups. Cross-sectional comparisons indicated that stride time variability was lower in the TC-expert vs. TC-naïve group, significantly so during DT (2.11 vs. 2.55%; p = 0.027); by contrast, gait speed during both undisturbed and DT conditions did not differ between groups. Longitudinal analyses of TC-naïve adults randomized to 6 months of TC training or usual care identified improvement in DT gait speed in both groups. A small improvement in DT stride time variability (effect size = 0.2) was estimated with TC training, but no significant differences between groups were observed. Potentially important improvements after TC training could not be excluded in this small study.
  
  
  CONCLUSIONS
  In healthy active older adults, positive effects of short- and long-term TC were observed only under cognitively challenging DT conditions and only for stride time variability. DT stride time variability offers a potentially sensitive metric for monitoring TC's impact on fall risk with healthy older adults.
authors.affiliation: Division of Preventive Medicine, Osher Center for Integrative Medicine, Brigham and Women's Hospital , Boston, MA , USA ; Harvard Medical School , Boston, MA , USA.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Wayne
authors.affiliation: Department of Neurology, Center for the Study of Movement, Cognition, and Mobility, Tel Aviv Sourasky Medical Center, Tel Aviv University , Tel Aviv , Israel.
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Hausdorff
authors.affiliation: Institute for Aging Research, Hebrew Senior Life , Boston, MA , USA.
authors.forename: Matthew
authors.initials: M
authors.lastname: Lough
authors.affiliation: Division of Preventive Medicine, Osher Center for Integrative Medicine, Brigham and Women's Hospital , Boston, MA , USA ; Harvard Medical School , Boston, MA , USA.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Gow
authors.affiliation: Institute for Aging Research, Hebrew Senior Life , Boston, MA , USA.
authors.forename: Lewis
authors.initials: L
authors.lastname: Lipsitz
authors.affiliation: Department of Neurology, Beth Israel Deaconess Medical Center , Boston, MA , USA.
authors.forename: Vera
authors.initials: V
authors.lastname: Novak
authors.affiliation: Harvard Medical School , Boston, MA , USA ; Biostatistics Center, Massachusetts General Hospital , Boston, MA , USA.
authors.forename: Eric A
authors.initials: EA
authors.lastname: Macklin
authors.affiliation: Division of Interdisciplinary Medicine and Biotechnology, Beth Israel Deaconess Medical Center , Boston, MA , USA ; Center for Dynamical Biomarkers and Translational Medicine, National Central University , Chungli , Taiwan.
authors.forename: Chung-Kang
authors.initials: CK
authors.lastname: Peng
authors.affiliation: Institute for Aging Research, Hebrew Senior Life , Boston, MA , USA.
authors.forename: Brad
authors.initials: B
authors.lastname: Manor
keywords: Tai Chi; cognition; dual task performance; falls and fall risk prevention; gait analysis