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The phenomenon of crosslimb transfer, in which unilateral strength training can result in bilateral strength gains, has recently been tested for ballistic movements. Performance gains associated with repetitive motor practice, and the associated transfer, occur within a few minutes. In this study, young and older adults were trained to perform ballistic abductions of their dominant (right) index finger as quickly as possible. Performance was assessed bilaterally before, during, and after this training. Both groups exhibited large performance gains in the right hand as a result of training (P < 0.001; young 84% improvement, older 70% improvement), which were not significantly different between groups (P = 0.40). Transcranial magnetic stimulation revealed that the performance improvements were accompanied by increases in excitability,together with decreases in intracortical inhibition, of the projections to both the trained muscle and the homologous muscle in the contralateral limb (P < 0.05). The young group also exhibited performance improvements as a result of cross-limb transfer in the left (untrained) hand (P < 0.005), equivalent to 75% of the performance increase in the trained hand. In contrast, there were no significant performance gains in the left hand for the older group (P = 0.23). This was surprising given that the older group exhibited a significantly greater degree of mirror activity than the young group (P < 0.01) in the left first dorsal interosseus muscle (FDI) during right hand movements. Our findings suggest that older adults exhibit a reduced capacity for cross-limb transfer, which may have implications for motor rehabilitation programs after stroke.

Item Type:	Refereed Article
Keywords:	aging; motor learning; plasticity; transcranial magnetic stimulation
Research Division:	Psychology and Cognitive Sciences
Research Group:	Psychology
Research Field:	Sensory Processes, Perception and Performance
Objective Division:	Expanding Knowledge
Objective Group:	Expanding Knowledge
Objective Field:	Expanding Knowledge in Psychology and Cognitive Sciences
Author:	Hinder, MR (Dr Mark Hinder)
Author:	Schmidt, MW (Mr Matthew Schmidt)
Author:	Garry, MI (Dr Michael Garry)
Author:	Summers, JJ (Professor Jeffery Summers)
ID Code:	71772
Year Published:	2011
Web of Science® Times Cited:	41
Deposited By:	Psychology
Deposited On:	2011-08-05
Last Modified:	2017-11-05
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