Transition Between the Timed up and Go Turn to Sit Subtasks: Is Timing Everything?

Area of Science:

• Gerontology
• Biomedical Engineering
• Movement Science

Background:

• The Timed Up and Go (TUG) test is a widely used mobility assessment.
• Its subtasks are well-studied, but the transitions between them are not.
• Understanding these transitions may reveal new aspects of mobility impairment.

Purpose of the Study:

• To investigate the hypothesis that longer transition durations between the turning and sitting subtasks of the TUG are associated with worse motor and cognitive performance in older adults.
• To explore different strategies older adults use during this transition.

Main Methods:

• 1055 older adults performed the TUG while wearing a 3D inertial sensor.
• Linear regressions analyzed the association between transition durations (D-interval and O-interval) and motor/cognitive functions.
• Participants' transition strategies (distinct vs. overlapping) were categorized.

Main Results:

• Two transition strategies were observed: distinct (77.34%) and overlapping (22.65%).
• Longer transition durations (D-interval and O-interval) correlated with worse TUG performance, poorer motor function (gait speed, bradykinesia, rigidity), and lower cognitive function (perceptual speed).
• Distinct transitions were associated with worse gait speed and bradykinesia, while overlapping transitions were linked to increased rigidity.

Conclusions:

• Older adults utilize distinct or overlapping strategies when transitioning from turning to sitting during the TUG.
• Instrumented TUG analysis of transition durations provides novel metrics beyond traditional assessments.
• These findings suggest new targets for interventions aimed at reducing late-life gait impairments.