Impaired depth perception and restricted pitch head movement increase obstacle contacts when dual-tasking in older people

Abstract

Background.Trips are the largest contributor to falls in older people, yet little is known about the underlying physiological mechanisms for safe obstacle negotiation. The aims of the study were to determine (i) the effect of a secondary visual task on obstacle contacts when older people negotiated an obstacle course and (ii) physiological factors associated with obstacle contacts.Methods.Thirty community-living adults aged 65 years and older walked along a 14.5-m walkway containing 21 obstacles with and without a secondary task. The secondary task required participants to call out a series of letters presented in front of them at head height and the suit of a playing card framed on the sidewall. Obstacle contacts, secondary task errors, eye peak-to-peak pitch amplitude and head peak-to-peak pitch amplitude (PA-H), and head angle in pitch were measured. Participants also completed assessments of sensorimotor function and balance.Results.Compared with the obstacle-only trials, participants performed the dual-task trials more slowly (p