title: Age-related differences in pre-movement antagonist muscle co-activation and reaction-time performance.
abstract: Multiple causes contribute to the prolonged reaction-times (RT) observed in elderly persons. The involvement of antagonist muscle co-activation remains unclear. Here the Mm. Biceps and Triceps Brachii activation in 64 apparently healthy elderly (80 ± 6 years) and 60 young (26 ± 3 years) subjects were studied during a simple RT-test (moving a finger using standardized elbow-extension from one pushbutton to another following a visual stimulus). RT was divided in pre-movement-time (PMT, time for stimulus processing) and movement-time (MT, time for motor response completion). RT-performance was significantly worse in elderly compared to young; the slowing was more pronounced for MT than PMT (respectively 101 ± 10 ms and 41 ± 6 ms slower, p<0.01). Elderly subjects showed significantly higher (p<0.01) antagonist muscle co-activation during the PMT-phase, which was significantly related to worse MT and RT (p<0.01). During the MT-phase, antagonist muscle co-activation was similar for both groups. It can be concluded that increased antagonist muscle co-activation in elderly persons occurs in an early phase, already before the start of the movement. These findings provide further understanding of the underlying mechanisms of age-related slowing of human motor performance.
authors.affiliation: Frailty in Ageing research Unit, Vrije Universiteit Brussel, Laarbeeklaan 103, B-1090 Brussels, Belgium. ivan.bautmans@vub.ac.be
authors.forename: Ivan
authors.initials: I
authors.lastname: Bautmans
authors.forename: Stijn
authors.initials: S
authors.lastname: Vantieghem
authors.forename: Ellen
authors.initials: E
authors.lastname: Gorus
authors.forename: Yuri-Reva
authors.initials: YR
authors.lastname: Grazzini
authors.forename: Yves
authors.initials: Y
authors.lastname: Fierens
authors.forename: Annelies
authors.initials: A
authors.lastname: Pool-Goudzwaard
authors.forename: Tony
authors.initials: T
authors.lastname: Mets
mesh_terms: D000328:Adult; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology* / Q000503:physiopathology; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology*