It has long been known that practice of motor tasks with one limb improves not only the performance of the trained but also of the opposite untrained limb (e.g. Carrol et al. 2008). However, learning-related improvements in performance may also be hindered if we are engaged in subsequent learning of a different, interfering motor task. Specifically, the motor performance of a recently learned task A can be reduced if a second task B is learned shortly afterwards (Brashers-Krug et al. 1996, Lundbye-Jensen et al. 2010). So far, the interference effect was only demonstrated for the limb actively involved in the training and not for the contralateral untrained limb. Therefore, the aim of the present study was to test learning-related interference in the limb contralateral to the trained one. Methods: In the present study, 46 subjects practiced ballistic isometric contractions with their index finger (task A). Subsequently, subjects were split into 4 groups practicing a visuomotor tracking (interference) task (task B) for either 6min (group A), 12min (group B), rested for 6min (group C) or 12min (group D), respectively. Results: Ballistic training caused an improvement in performance of the trained hand of 41.5 ± 4.5% (p = <0.001) and in the untrained contralateral hand of 23.8 ± 3.8% (p = <0.001) in all subjects. Interference training of 6min (group A) caused a significant reduction of performance only for the trained hand (-22.7 ± 4.3%; p = <0.001) but not the untrained contralateral hand. The 12min visuomotor tracking (group B), however, showed a significantly reduced performance of the trained (-22.72 ± 4.1%; p = <0.001) and untrained contralateral hand (-19.1 ± 4.8%; p = <0.001). Groups C and D did not show significant interference effects. Discussion: The results of the present study show for the first time that subsequent learning of an interfering motor task can not only cause reduced performance in the trained limb but also in the untrained contralateral limb. This interference effect was shown to depend on the training duration of the interference task. These findings might have important clinical implications for movement rehabilitation programs in patients suffering from hemiparesis, e.g. after stroke.
© Copyright 2012 17th Annual Congress of the European College of Sport Science (ECSS), Bruges, 4. -7. July 2012. Veröffentlicht von Vrije Universiteit Brussel. Alle Rechte vorbehalten.