Age-related differences in pre-movement antagonist muscle co-activation and reaction-time performance

• Published in: Experimental gerontology 2011-08, Vol.46 (8), p.637-642
• Main Authors: Bautmans, Ivan, Vantieghem, Stijn, Gorus, Ellen, Grazzini, Yuri-Reva, Fierens, Yves, Pool-Goudzwaard, Annelies, Mets, Tony
• Format: Article
• Language: English
• Subjects: Adult; Aged, 80 and over; Ageing; Aging - physiology; Antagonist co-contraction; Electromyography; Female; Geriatry and gerontology; Human health and pathology; Humans; Life Sciences; Male; Movement - physiology; Muscle Contraction - physiology; Muscle, Skeletal - physiology; Muscle, Skeletal - physiopathology; Psychomotor Performance - physiology; Reaction time; Reaction Time - physiology; Skeletal muscle
• ISSN: 0531-5565; 1873-6815
• DOI: 10.1016/j.exger.2011.03.002

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. ► We studied antagonist muscle co-activation during a reaction time test. ► Elderly show higher antagonist co-activation, already before the start of movement. ► This is significantly related to worse reaction time performance. ► We provide further understanding of age-related slowing of human motor performance.