Steven C. Cramer was supported by grants from the American Heart Association and the National Institute of Child Health and Human Development. Sally Waddle and Julie A. Bodwell were supported by fellowships from the American Heart Association.
Age and Features of Movement Influence Motor Overflow
Version of Record online: 20 NOV 2003
Journal of the American Geriatrics Society
Volume 51, Issue 12, pages 1735–1739, December 2003
How to Cite
Bodwell, J. A., Mahurin, R. K., Waddle, S., Price, R. and Cramer, S. C. (2003), Age and Features of Movement Influence Motor Overflow. Journal of the American Geriatrics Society, 51: 1735–1739. doi: 10.1046/j.1532-5415.2003.51557.x
- Issue online: 20 NOV 2003
- Version of Record online: 20 NOV 2003
- motor overflow;
- mirror movements;
- aging; healthy;
Objectives: To measure the magnitude and prevalence of motor overflow to the arm at rest during attempted unilateral arm movements.
Design: Cross-sectional assessment.
Setting: Motor physiology laboratory.
Participants: Healthy young (n=20) and elderly (n=20) adult subjects.
Measurements: Surface electromyography (EMG) was obtained from bilateral forearm muscles during performance of 12 different unilateral finger-tapping tasks.
Results: For all subjects, faster movement rate (F=2.56–3.30, P<.05), cognitive distraction (F=4.09, P<.05), and fatigue (F=15.15, P<.001) were each associated with a significant increase in the magnitude of EMG in the arm intended to be at rest. In elderly subjects, tapping at maximum rate and fatigue were each associated with a further increase in motor overflow across the midline. In addition, better left hand dexterity correlated with greater motor overflow to the right hand during rapid left hand tapping (r=0.63, P<.005). Prevalence of motor overflow was also higher in older subjects for some tasks, for example during 1 Hz tapping by the right index finger (motor overflow present in 45%, vs 15% young subjects, P<.05).
Conclusion: Several behavioral variables increase motor overflow across the midline in young and elderly adults. Motor overflow was even greater in elderly subjects with the most demanding tasks and was greater in those with better motor status, suggesting that this form of motor system change is a compensatory event of normal aging rather than age-related dysfunction. The results support the hypotheses that healthy aging is associated with an increase in the degree to which brain function is bilaterally organized.