title: Transition Between the Timed up and Go Turn to Sit Subtasks: Is Timing Everything?
abstract: The Timed Up and Go (TUG), one of the most widely used tests of mobility, has been validated and associated with adverse outcomes in the community, acute care, and nursing home setting. It is composed of several distinct subtasks; however, the temporal relationship when transitioning between subtasks has not been well-studied. We tested the hypothesis that longer transition durations between the final turn to the sitting subtasks are associated with worse motor and cognitive performance in older adults.
  
  
  
  A total of 1055 participants (80.33 ± 7.57 years, 76.96% female) performed the TUG while wearing a 3-dimensional inertial sensor on their lower back. We employed a series of linear regressions to examine the association of the duration between the turn and sitting subtasks with clinical characteristics including motor and cognitive functions.
  
  
  
  Participants employed 2 different strategies when they transitioned from turning to sitting. (1) Distinct transition strategy: 816 participants (77.34%) first completed the turn before starting to sit. The average duration between these distinct subtasks (D-interval) was 715 ± 980 ms. (2) Overlapping transition strategy: 239 participants (22.65%) started to sit before completing the turn. The average overlap duration between these tasks (O-interval) was 237 ± 269 ms. Participants who employed the distinct transition strategy were slightly younger than those who employed the overlapping transition strategy (P ≤ .013). Higher D-intervals and O-intervals were associated with worse TUG performance (P ≤ .02), with poorer motor and cognitive function, [ie, worse parkinsonian gait (P ≤ .001), lower level of perceptual speed (P ≤ .03), and with worse mobility disability (P ≤ .001)]. A longer D-interval was associated with worse gait speed and bradykinesia (P ≤ .001), whereas a longer O-interval was associated with increased rigidity (P = .004).
  
  
  
  Older adults apparently employ 2 different strategies when transitioning from turning to sitting. The instrumented TUG can characterize additional gait and balance aspects that cannot be derived from traditional TUG assessments. These new measures offer novel targets for intervention to decrease the burden of late-life gait impairment.
authors: Center for the Study of Movement, Cognition, and Mobility, Neurological Institute, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel.
authors: Aner
authors: A
authors: Weiss
authors: Center for the Study of Movement, Cognition, and Mobility, Neurological Institute, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel; Department of Physical Therapy, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors: Anat
authors: A
authors: Mirelman
authors: Center for the Study of Movement, Cognition, and Mobility, Neurological Institute, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel; Department of Physical Therapy, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; Department of Neurology, Sackler Faculty of Medicine, and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel.
authors: Nir
authors: N
authors: Giladi
authors: Rush Alzheimer's Disease Center, Rush University Medical Center, Chicago, IL; Department of Neurological Sciences, Rush University Medical Center, Chicago, IL; Department of Behavioral Sciences, Rush University Medical Center, Chicago, IL.
authors: Lisa L
authors: LL
authors: Barnes
authors: Rush Alzheimer's Disease Center, Rush University Medical Center, Chicago, IL; Department of Neurological Sciences, Rush University Medical Center, Chicago, IL.
authors: David A
authors: DA
authors: Bennett
authors: Rush Alzheimer's Disease Center, Rush University Medical Center, Chicago, IL; Department of Neurological Sciences, Rush University Medical Center, Chicago, IL.
authors: Aron S
authors: AS
authors: Buchman
authors: Center for the Study of Movement, Cognition, and Mobility, Neurological Institute, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel; Department of Physical Therapy, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel. Electronic address: jhausdor@tlvmc.gov.il.
authors: Jeffrey M
authors: JM
authors: Hausdorff
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D060825:Cognitive Dysfunction / Q000175:diagnosis; D004185:Disability Evaluation; D005260:Female; D015577:Geriatric Assessment / Q000379:methods*; D006801:Humans; D008297:Male; D018670:Monitoring, Ambulatory / Q000295:instrumentation; D009043:Motor Activity; D011930:Reaction Time / Q000502:physiology*; D013647:Task Performance and Analysis; D013997:Time Factors
keywords: Aging; Timed Up and Go; accelerometers; cognition; disability; inertial sensors; turn-to-sit