title: Effects of aging on the relationship between cognitive demand and step variability during dual-task walking.
abstract: A U-shaped relationship between cognitive demand and gait control may exist in dual-task situations, reflecting opposing effects of external focus of attention and attentional resource competition. The purpose of the study was twofold: to examine whether gait control, as evaluated from step-to-step variability, is related to cognitive task difficulty in a U-shaped manner and to determine whether age modifies this relationship. Young and older adults walked on a treadmill without attentional requirement and while performing a dichotic listening task under three attention conditions: non-forced (NF), forced-right (FR), and forced-left (FL). The conditions increased in their attentional demand and requirement for inhibitory control. Gait control was evaluated by the variability of step parameters related to balance control (step width) and rhythmic stepping pattern (step length and step time). A U-shaped relationship was found for step width variability in both young and older adults and for step time variability in older adults only. Cognitive performance during dual tasking was maintained in both young and older adults. The U-shaped relationship, which presumably results from a trade-off between an external focus of attention and competition for attentional resources, implies that higher-level cognitive processes are involved in walking in young and older adults. Specifically, while these processes are initially involved only in the control of (lateral) balance during gait, they become necessary for the control of (fore-aft) rhythmic stepping pattern in older adults, suggesting that attentional resources turn out to be needed in all facets of walking with aging. Finally, despite the cognitive resources required by walking, both young and older adults spontaneously adopted a "posture second" strategy, prioritizing the cognitive task over the gait task.
authors.affiliation: UMR-S 1075 COMETE (Mobilités: Attention, Orientation, Chronobiologie) INSERM and Université de Caen Normandie, Pôle des Formations et de Recherche en Santé, 2 rue des Rochambelles, 14032, Caen Cedex 5, France. leslie.decker@unicaen.fr.|University of Nebraska at Omaha, Biomechanics Research Building, 6160 University Drive, Omaha, NE, 68182-0860, USA. leslie.decker@unicaen.fr.
authors.forename: Leslie M
authors.initials: LM
authors.lastname: Decker
authors.affiliation: UMR 7291 CNRS and Aix-Marseille Université, 3 place Victor-Hugo, 13331, Marseille Cedex 3, France.
authors.forename: Fabien
authors.initials: F
authors.lastname: Cignetti
authors.affiliation: Department of Integrative Biology, University of California, Berkeley, 3040 Valley Life Sciences Building #3140, Berkeley, CA, 94720-3140, USA.
authors.forename: Nathaniel
authors.initials: N
authors.lastname: Hunt
authors.affiliation: Division of Geriatrics and Gerontology, University of Nebraska Medical Center, 986155 Nebraska Medical Center, Omaha, NE, 68198-6155, USA.
authors.forename: Jane F
authors.initials: JF
authors.lastname: Potter
authors.affiliation: University of Nebraska at Omaha, Biomechanics Research Building, 6160 University Drive, Omaha, NE, 68182-0860, USA.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Stergiou
authors.affiliation: Translational Gerontology Branch, Longitudinal Studies Section, National Institute on Aging, 251 Bayview Blvd., Suite 100, Rm 04B316, Baltimore, MD, 21224, USA.
authors.forename: Stephanie A
authors.initials: SA
authors.lastname: Studenski
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology* / Q000523:psychology*; D003071:Cognition; D005684:Gait; D006801:Humans; D000070857:Walk Test; D055815:Young Adult
keywords: Aging; Cognitive control; Gait; Resource competition; Step variability