Effects of ageing on responses to stepping-target displacements during walking
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ORIGINAL ARTICLE
Effects of ageing on responses to stepping‑target displacements during walking Yajie Zhang1,2 · Jeroen B. J. Smeets2 · Eli Brenner2 · Sabine Verschueren1 · Jacques Duysens3 Received: 16 March 2020 / Accepted: 19 September 2020 © The Author(s) 2020
Abstract Purpose Human sensory and motor systems deteriorate with age. When walking, older adults may therefore find it more difficult to adjust their steps to new visual information, especially considering that such adjustments require control of balance as well as of foot trajectory. Our study investigates the effects of ageing on lower limb responses to unpredictable target shifts. Methods Participants walked on a treadmill with projected stepping targets that occasionally shifted in the medial or lateral direction. The shifts occurred at a random moment during the early half of the swing phase of either leg. Kinematic, kinetic and muscle activity data were collected. Results Older adults responded later and corrected for a smaller proportion of the shift than young adults. The order in which muscle activation changed was similar in both groups, with responses of gluteus medius and semitendinosus from about 120 to 140 ms after the shift. Most muscles responded slightly later to lateral target shifts in the older adults than in the young adults, but this difference was not observed for medial target shifts. Ageing delayed the behavioural responses more than it did the electromyographic (EMG) responses. Conclusions Our study suggests that older adults can adjust their walking to small target shifts during the swing phase, but not as well as young adults. Furthermore, muscle strength probably plays a substantial role in the changes in online adjustments during ageing. Keywords Target jump · Correction · Elderly · Leg adjustments · Force Abbreviations ANOVA Analysis of variance BF Biceps femoris c- Contralateral COP Centre of pressure EMG Electromyography GaL Gastrocnemius lateralis GaM Gastrocnemius medialis Communicated by Lori Ann Vallis. * Yajie Zhang [email protected] 1
Department of Rehabilitation Sciences, FaBer, KU Leuven, Leuven, Belgium
2
Department of Human Movement Sciences, Amsterdam Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
3
Motor Control Laboratory, Movement Control and Neuroplasticity Research Group, FaBer, KU Leuven, Leuven, Belgium
GlM Gluteus medius i- Ipsilateral MVC Maximal voluntary contraction SEM Standard error of the mean ST Semitendinosus TA Tibialis anterior TUG Timed up and go VL Vastus lateralis VM Vastus medialis
Introduction When walking, the movements of one’s feet are continuously controlled based on the latest visual information (Zhang et al. 2020), which makes it possible to adjust one’s steps. Adjusting steps when walking is very common in daily life. Incorrectly adjusting a step during walking can affect balance which can lead to a fall. With ageing, the ability to maintain balance decreases, including maintaining balance during wa
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