title: Non-MTC gait cycles: An adaptive toe trajectory control strategy in older adults.
abstract: Minimum-toe-clearance (MTC) above the walking surface is a critical representation of toe-trajectory control due to its association with tripping risk. Not all gait cycles exhibit a clearly defined MTC within the swing phase but there have been few previous accounts of the biomechanical characteristics of non-MTC gait cycles. The present report investigated the within-subject non-MTC gait cycle characteristics of 15 older adults (mean 73.1 years) and 15 young controls (mean 26.1 years). Participants performed the following tasks on a motorized treadmill: preferred speed walking, dual task walking (carrying a glass of water) and a dual-task speed-matched control. Toe position-time coordinates were acquired using a 3 dimensional motion capture system. When MTC was present, toe height at MTC (MTCheight) was extracted. The proportion of non-MTC gait cycles was computed for the age groups and individuals. For non-MTC gait cycles an 'indicative' toe height at the individual's average swing phase time (MTCtime) for observed MTC cycles was averaged across multiple non-MTC gait cycles. In preferred-speed walking Young demonstrated 2.9% non-MTC gait cycles and Older 18.7%. In constrained walking conditions both groups increased non-MTC gait cycles and some older adults revealed over 90%, confirming non-MTC gait cycles as an ageing-related phenomenon in lower limb trajectory control. For all participants median indicative toe-height on non-MTC gait cycles was greater than median MTCheight. This result suggests that eliminating the biomechanically hazardous MTC event by adopting more of the higher-clearance non-MTC gait cycles, is adaptive in reducing the likelihood of toe-ground contact.
authors.affiliation: Institute of Sport, Exercise and Active Living, Victoria University, Melbourne, Victoria 8001, Australia; College of Sport & Exercise Science, Victoria University, Melbourne, Victoria 8001, Australia. Electronic address: braveena.santhiranayagam@live.vu.edu.au.
authors.forename: Braveena K
authors.initials: BK
authors.lastname: Santhiranayagam
authors.affiliation: Institute of Sport, Exercise and Active Living, Victoria University, Melbourne, Victoria 8001, Australia; College of Sport & Exercise Science, Victoria University, Melbourne, Victoria 8001, Australia. Electronic address: tony.sparrow@vu.edu.au.
authors.forename: W A
authors.initials: WA
authors.lastname: Sparrow
authors.affiliation: Institute of Sport, Exercise and Active Living, Victoria University, Melbourne, Victoria 8001, Australia; College of Engineering & Science, Victoria University, Melbourne, Victoria 8001, Australia. Electronic address: daniel.lai@vu.edu.au.
authors.forename: Daniel T H
authors.initials: DTH
authors.lastname: Lai
authors.affiliation: Institute of Sport, Exercise and Active Living, Victoria University, Melbourne, Victoria 8001, Australia; College of Sport & Exercise Science, Victoria University, Melbourne, Victoria 8001, Australia. Electronic address: rezaul.begg@vu.edu.au.
authors.forename: Rezaul K
authors.initials: RK
authors.lastname: Begg
mesh_terms: D000058:Accidental Falls / Q000517:prevention & control*; D000328:Adult; D000368:Aged; D000375:Aging; D001696:Biomechanical Phenomena; D005080:Exercise Test; D005260:Female; D005684:Gait; D006801:Humans; D008297:Male; D011795:Surveys and Questionnaires; D014034:Toes / Q000502:physiology*; D016138:Walking
keywords: Ageing; Dual task walking; Gait adaptation; Minimum-toe-clearance (MTC); Non-MTC gait cycles; Toe-trajectory control