TIMING AND COORDINATION OF GAIT: IMPACT OF AGING, GAIT SPEED AND RHYTHMIC AUDITORY CUEING

Purpose: The aims of this dissertation were to: 1) compare the test-retest reliability and determine minimal detectable change (MDC) of spatial and temporal gait variability in younger and older adults 2) examine the impact of challenging walking conditions (slower and faster speeds) on gait variability in younger and older adults and 3) examine the impact of rhythmic auditory cueing (metronome) on the walk ratio as an indicator of the spatial and temporal coordination of gait at different walking speeds in healthy adults. \ud Subjects: Forty younger (mean age = 26.6 ± 6.0 years) and 120 older adults (mean age = 78.1 ± 6.2 years) independent in ambulation were studied. \ud Methods: Gait characteristics were collected using a computerized walkway (GaitMat II™). Step length, step width, step time, swing time, stance time and double support time variability were derived as the standard deviation of all steps across the 4 passes. Cadence and walk ratio were also calculated.\ud Analyses: Test-retest reliability was calculated using Intra-class correlation coefficients (ICCs(2,1) ), relative limits of agreement (LoA%) and standard error of measurement (SEM). The MDC at 90% and 95% level were also calculated. Mixed linear models were used to determine differences in gait variability between younger and older by walking conditions and with metronome cues.\ud Results and Clinical Relevance: Younger adults had greater test-retest reliability and smaller MDC of spatial and temporal gait variability compared to older adults. In older adults, walking slowly is more challenging to the motor control of gait and may be more sensitive to age-related declines in gait than usual and faster speed walks. Finally, a metronome-cue, commonly used in gait rehabilitation, may have been detrimental to the walking pattern. It is possible that the metronome-cue disrupts gait timing by increasing the attentional demand of walking at non-ideal speeds such as slower and faster speeds. Future research should further investigate inconsistency of gait variability as a potential early indicator of a decline in mobility. Also, future longitudinal studies are needed to determine if changes in gait variability on challenging gait conditions predict future mobility disability in older adults with near normal gait