Research Report
Population: Adult
Min Hui Huang, PT, PhD, NCS, Assistant Professor, Physical Therapy Department, University of Michigan-Flint mhhuang@umflint.edu
Kelly Newman, BS, Student physical therapist, Physical Therapy Department, University of Michigan-Flint newmanke@umflint.edu
Tracy Shilling, PT, DPT, Physical Therapist, Children’s Therapy Corner t.m.lytle@umflint.edu
Austin Righter, BS, Student physical therapist, Physical Therapy Department, University of Michigan-Flint arighter@umflint.edu
Kara Miller, PT, DPT, Physical therapist, Beaumont Health System kara.miller@beaumont.edu
Keywords: Prevention, Postural Balance, Falls, Aging
Purpose/Hypothesis:
Anticipatory postural adjustments (APA) are produced prior to movement initiation to stabilize posture. APA are programmed to counter the estimated disturbance to posture. Whether older adults with a history of falls can modulate APA according to the disturbance of a task remains unclear. We examined postural control during reaching to different loads in young, older adults without (non-fallers) and with (fallers) a history of falls. We hypothesized that APA and dynamic balance would differ between groups and across trials of reaching to different loads.
Subjects:
17 young adults (25±2.1 years), 11 non-fallers (65±9.2 years), and 12 fallers (68±7.3 years) living in the community volunteered. All were able to walk >50 ft without another person’s assistance and with no history of neurologic conditions.
Materials/Methods:
Participants performed the task in standing as fast as possible. They reached forward to grasp a basket placed at 30 cm in front of the feet on the floor using both hands, and returned to an upright posture while holding the basket. The basket’s weight was altered in the following sequence: 2.2 Kg, 0 Kg, and 2.2 Kg. Participants performed 3 trials in each load condition while data from the 1st and 3rd trials of a condition were included to analyze changes in postural stability across trials. Center of pressure (COP) was analyzed during 3 phases of the task: APA, reaching to the target, and returning to upright. Postural parameters were COP displacement during APA as well as maximum COP forward displacement, COP peak velocity, and COP trajectory smoothness during reaching and returning. Fallers and non-fallers were also assessed using the Balance Evaluation Systems Test (BESTest). Linear Mixed Model was used to analyze postural parameters, with group as between subject factor, trial as within subject factor, and Tukey’s LSD for post-hoc comparisons. Independent t-test compared demographics and scores of the BESTest between fallers and non-fallers. Significance level was p<0.05.
Results:
The effect of trial was not significant in all COP variables. APA amplitudes and durations were significantly larger in fallers than young adults and non-fallers (p<0.01). Fallers had significantly smaller COP forward displacement than non-fallers (p<0.05) and young adults (p<0.01). In contrast, COP peak velocities during reaching and returning phases were comparable between groups. During reaching and returning, COP trajectory smoothness was significantly reduced in fallers compared to non-fallers and young adults (p<0.01). Scores of the BESTest were comparable between fallers and non-fallers.
Conclusions:
Older adults retain the ability to modulate APA according to the weight of reaching targets. However, fallers achieved this by altering APA amplitudes and durations. The control of COP trajectories during movement execution is compromised with aging and a history of falls.
Clinical Relevance:
Current findings suggest that COP variables may be more sensitive and precise in identifying older adults with fall risks compared to clinical balance tests.
Citation:
Huang, Min Hui , PT, PhD, NCS; Newman, Kelly , BS; Shilling, Tracy , PT, DPT; Righter, Austin , BS; Miller, Kara , PT, DPT. Postural parameters associated with anticipatory postural adjustments and during movement execution are altered in older adults with a history of falls.. Poster Presentation. IV STEP Conference, American Physical Therapy Association, Columbus, OH, July 17, 2016. Online. https://u.osu.edu/ivstep/poster/abstracts/104_huang-et-al/