TRANSFER OF A TRAINED SEQUENTIAL REACHING SKILL FROM THE UPPER EXTREMITY TO THE IPSILATERAL LOWER EXTREMITY IN YOUNG ADULTS

O. Elion¹, Z. Kozol¹, M. Einat², S. Frenkel-Toledo^1,3

¹Ariel University, Department of Physiotherapy, Ariel, Israel, ²Ariel University, Department of Electrical and Electronic Engineering, Ariel, Israel, ³Loewenstein Hospital, Department of Neurological Rehabilitation, Raanana, Israel

Background: Applying the principles of motor learning is crucial for improving motor skill acquisition in healthy adults and individuals with neurological and orthopedic impairments. Contralateral, inter-hemispheric transfer of strength and skill in the upper extremities has been widely described in healthy and post-stroke individuals. However, data about ipsilateral, intra-hemispheric transfer is rather sparse, specifically, it is not clear whether training of the upper extremity (UE) enhances the performance of the ipsilateral lower extremity (LE).

Purpose: To study the transfer characteristics of a sequential reaching task from the UE to the ipsilateral LE.

Methods: Fourty-five young adults participated in a single-blinded randomized controlled study. They were randomly allocated to one of three groups (N=15), with the following intervention conditions:
a) performing a sequential reaching task of the non-dominant left UE towards a five switch-led apparatus which lit up in a predetermined sequence (training group - TR),
b) Observation of the switch-led apparatus which lit up in the same sequence as the TR group (Observation group – OB), and
c) Watching a nature video (video group – VI).
The performance of the sequence with the non-dominant LE was measured by the time(msec) of reaching, before, right after, and 24 hours after the initial training.

Results: Reaching time in all three groups was similar before the intervention but was significantly faster right after the intervention only in the TR group, compared to the VI group. 24 hours after the training session there was no further decrease in reaching time in the TR and OB groups.

Conclusions: Ipsilateral transfer of a sequential reaching task from the UE to the LE was evident only on right after the training session, but not 24 h after the training. The cognitive component of observing the sequence may have partially contributed to the performance of the reaching task, but by itself, was not as robust compared to combining actual performance and cognitive elements, as was observed in the training group. Finally, it may be inferred that only partial transfer was triggered since the UE training improved the performance of the reaching task in the LE on the same day of training but, seems to have interfered with the consolidation process 24 h after the training.

Implications: Altogether ipsilateral transfer may be an effective method for improving treatment outcomes. The current data suggest that in-order to optimize training gains and ipsilateral transfer special attention must be paid to the contents and to the number of repetitions of the training session. Firstly, the number of repetitions of the task may have a role in triggering or preventing the transfer of the task. Secondly, active performance, and not only observation is essential for triggering a significant ipsilateral transfer process. Thus, our data may suggest that treatment (training) sessions should be carefully planned, adhering to the constraints of motor skill acquisition.

Funding acknowledgements: This study was not funded

Keywords:
ipsilateral transfer
lower extremity
upper extremity

Topics:
Research methodology, knowledge translation & implementation science
Professional practice: other
Musculoskeletal: lower limb

Did this work require ethics approval? Yes

Institution: Ariel University, Israel

Committee: Ethics Committee of Ariel University, Israel

Ethics number: AU-HEA-OE-20210610