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The campus community is invited to the dissertation defense of Elham (Elli) Alijanpour. See the details below regarding the defense location, date, and time. 

Dissertation title:  Step by step: understanding age-related differences in gait coordination and efficiency

Location and time: Monday, June 29th, 10am - 12pm in HS2 1001.

Zoom meeting option:

Meeting ID: 946 7337 5812

Abstract

Aging is accompanied by slower walking speed and higher energetic cost, yet the mechanisms linking coordination and efficiency across the adult lifespan remain poorly understood. This dissertation examined how lower extremity coordination and sequencing of leg forces during the step to step transition (STST) relate to the energetic cost of walking in healthy young, middle aged, and older adults. Grounded in a dynamical systems framework, I treated aging not as failure of a “young” template, but as a shift in organismic constraints that gives rise to new, adaptive coordination patterns. In Study 1, we used a novel gait phase normalization method and continuous relative phase analysis to compare intra and interlimb coordination at participants’ preferred walking speed. Age-related differences were not uniform across the gait cycle.  They were concentrated around the STST, where older adults exhibited altered coordination timing compared to younger adults. In Study 2, we evaluated the Sequence (S) index, a measure of overlap between push off and collision forces during walking gait, as a marker of STST mechanical efficiency across speeds scaled to preferred walking speed. Older adults showed consistently higher S index values compared to young adults, driven by both altered timing and reduced single support impulses, indicating greater cancellation of positive and negative work during STST among older adults. In Study 3, we measured S index and the metabolic energetic cost of walking in young, middle aged, and older adults at 80%, 100%, and 120% of preferred speed. Lower S index was associated with lower energetic cost across all groups, with the strongest relationship at and below preferred speed. Older adults demonstrated the highest energetic costs despite sharing a similar S index–cost slope with younger groups. Together, these studies identify STST and leg force sequencing as key gait components influenced by aging, establish the S index as a mechanistically meaningful marker of walking efficiency, and provide a lifespan framework for designing interventions that consider the dynamics of the aging body.

The committee consists of:

Dr. Heather Hamilton (chair), Dr. Hunter Bennett, and Dr. Patrick Wilson