title: Complexity-Based Measures Inform Effects of Tai Chi Training on Standing Postural Control: Cross-Sectional and Randomized Trial Studies.
abstract: Diminished control of standing balance, traditionally indicated by greater postural sway magnitude and speed, is associated with falls in older adults. Tai Chi (TC) is a multisystem intervention that reduces fall risk, yet its impact on sway measures vary considerably. We hypothesized that TC improves the integrated function of multiple control systems influencing balance, quantifiable by the multi-scale "complexity" of postural sway fluctuations.
  
  
  
  To evaluate both traditional and complexity-based measures of sway to characterize the short- and potential long-term effects of TC training on postural control and the relationships between sway measures and physical function in healthy older adults.
  
  
  
  A cross-sectional comparison of standing postural sway in healthy TC-naïve and TC-expert (24.5±12 yrs experience) adults. TC-naïve participants then completed a 6-month, two-arm, wait-list randomized clinical trial of TC training. Postural sway was assessed before and after the training during standing on a force-plate with eyes-open (EO) and eyes-closed (EC). Anterior-posterior (AP) and medio-lateral (ML) sway speed, magnitude, and complexity (quantified by multiscale entropy) were calculated. Single-legged standing time and Timed-Up-and-Go tests characterized physical function.
  
  
  
  At baseline, compared to TC-naïve adults (n = 60, age 64.5±7.5 yrs), TC-experts (n = 27, age 62.8±7.5 yrs) exhibited greater complexity of sway in the AP EC (P = 0.023), ML EO (P<0.001), and ML EC (P<0.001) conditions. Traditional measures of sway speed and magnitude were not significantly lower among TC-experts. Intention-to-treat analyses indicated no significant effects of short-term TC training; however, increases in AP EC and ML EC complexity amongst those randomized to TC were positively correlated with practice hours (P = 0.044, P = 0.018). Long- and short-term TC training were positively associated with physical function.
  
  
  
  Multiscale entropy offers a complementary approach to traditional COP measures for characterizing sway during quiet standing, and may be more sensitive to the effects of TC in healthy adults.
  
  
  
  ClinicalTrials.gov NCT01340365.
authors.affiliation: Osher Center for Integrative Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, United States of America.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Wayne
authors.affiliation: Osher Center for Integrative Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, United States of America.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Gow
authors.affiliation: Division of Interdisciplinary Medicine and Biotechnology and Margret and H.A. Rey Institute for Nonlinear Dynamics in Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America.
authors.forename: Madalena D
authors.initials: MD
authors.lastname: Costa
authors.affiliation: Division of Interdisciplinary Medicine and Biotechnology and Margret and H.A. Rey Institute for Nonlinear Dynamics in Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America; Center for Dynamical Biomarkers and Translational Medicine, National Central University, Chungli, Taiwan.
authors.forename: C-K
authors.initials: CK
authors.lastname: Peng
authors.affiliation: Division of Gerontology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America; Institute for Aging Research, Hebrew SeniorLife, Roslindale, Massachusetts, United States of America.
authors.forename: Lewis A
authors.initials: LA
authors.lastname: Lipsitz
authors.affiliation: Movement Disorders Unit, Department of Neurology, Tel Aviv Medical Center, Tel Aviv, Israel; Department of Physical Therapy and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Hausdorff
authors.affiliation: Division of General Medicine and Primary Care, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America.
authors.forename: Roger B
authors.initials: RB
authors.lastname: Davis
authors.affiliation: Osher Center for Integrative Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, United States of America.
authors.forename: Jacquelyn N
authors.initials: JN
authors.lastname: Walsh
authors.affiliation: Institute for Aging Research, Hebrew SeniorLife, Roslindale, Massachusetts, United States of America.
authors.forename: Matthew
authors.initials: M
authors.lastname: Lough
authors.affiliation: Division of Gerontology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America; Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America.
authors.forename: Vera
authors.initials: V
authors.lastname: Novak
authors.affiliation: Division of General Medicine and Primary Care, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America.
authors.forename: Gloria Y
authors.initials: GY
authors.lastname: Yeh
authors.affiliation: Division of General Medicine and Primary Care, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America; Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, Massachusetts, United States of America.
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Ahn
authors.affiliation: Biostatistics Center, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America.
authors.forename: Eric A
authors.initials: EA
authors.lastname: Macklin
authors.affiliation: Division of Gerontology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America.
authors.forename: Brad
authors.initials: B
authors.lastname: Manor
mesh_terms: D000367:Age Factors; D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010809:Physical Fitness; D004856:Postural Balance / Q000502:physiology; D011187:Posture / Q000502:physiology; D026302:Tai Ji