Elsevier

Gait & Posture

Volume 56, July 2017, Pages 24-30
Gait & Posture

Full length article
Interlimb transfer of motor skill learning during walking: No evidence for asymmetric transfer

https://doi.org/10.1016/j.gaitpost.2017.04.032Get rights and content

Highlights

  • Interlimb transfer of motor skills can be therapeutic for individuals with stroke.

  • We tested the amount of interlimb transfer during walking in college-aged adults.

  • We also examined whether this interlimb transfer was asymmetric between legs.

  • Participants showed significant transfer of motor skills between legs.

  • In contrast to upper-limb literature, there was no evidence for asymmetric transfer.

Abstract

Several studies have shown that learning a motor skill in one limb can transfer to the opposite limb—a phenomenon called as interlimb transfer. The transfer of motor skills between limbs, however, has shown to be asymmetric, where one side benefits to a greater extent than the other. While this phenomenon has been well-documented in the upper-extremity, evidence for interlimb transfer in the lower-extremity is limited and mixed. This study investigated the extent of interlimb transfer during walking, and tested whether this transfer was asymmetric using a foot trajectory-tracking paradigm that has been specifically used for gait rehabilitation. The paradigm involved learning a new gait pattern which required greater hip and knee flexion during the swing phase of the gait while walking on a treadmill. Twenty young adults were randomized into two equal groups, where one group (right-to-left: RL) practiced the task initially with the dominant right leg and the other group (left-to-right: LR) practiced the task initially with their non-dominant left leg. After training, both groups practiced the task with their opposite leg to test the transfer effects. The changes in tracking error on each leg were computed to quantify learning and transfer effects. The results indicated that practice with one leg improved the motor performance of the other leg; however, the amount of transfer was similar across groups, indicating that there was no asymmetry in transfer. This finding is contradictory to most upper-extremity studies (where asymmetric transfer has been reported) and points out that both differences in neural processes and types of tasks may mediate interlimb transfer.

Introduction

The issue of “motor transfer” − i.e., the ability to learn a new motor skill and transfer it to another task or situation − is fundamental to learning and development, and is considered to be a key factor for motor recovery after neurologic or orthopedic injuries [1], [2]. One specific type of transfer is interlimb transfer where the neuromotor system retrieves information relevant to learning from the trained limb, and transfers it to the opposite, untrained limb [3], [4], [5], [6], [7]. This phenomenon of interlimb transfer is not only interesting from a theoretical standpoint of how movements are represented, but also to rehabilitation specialists, as it has therapeutic implications for individuals with unilateral deficits like stroke.

The concept of interlimb transfer has been studied extensively in the upper-limb, and various factors (e.g., type of task, conception of the task, spatial reference frame, duration of training, motor variability during training, ageing, sleep) have been identified to affect the extent and stability of transfer [8], [9], [10], [11], [12], [13], [14]. One specific finding is that the amount of interlimb transfer of motor learning appears to be asymmetric or side-specific, with one limb showing greater ability to learn from practice on the other limb [3], [5], [15], [16], [17]. Whether it is the dominant or non-dominant limb that shows greater transfer seems to be a function of the task, and this asymmetry has been linked to the idea of hand/hemispheric dominance [16], [18], [19], [20]. However, while there is strong evidence for this asymmetry in the upper limb, the evidence for inter-limb transfer in the lower-limb has been mixed. van Hedel et al. used a novel obstacle avoidance task to study the extent and asymmetry of transfer of motor skill learning from one leg to the other [21]. They observed a significant transfer of motor skills between limbs, but reported no asymmetry in the amount of transfer between limbs. In contrast, Houldin et al. evaluated the extent of interlimb transfer using a unipedal walking task and reported limited transfer of locomotor adaptations from the right leg to the left leg [22]. Finally, a recent study by Stockel and Wang [11] showed that the asymmetry in the lower limb was mediated by the task context, depending on whether the feedback was spatial (kinematic) or dynamic (force).

Given the paradigms used to investigate interlimb transfer in the lower limb have been varied, we investigated the amount of interlimb transfer in a paradigm that we have specifically used for gait rehabilitation [23], [24]. The paradigm involves a foot trajectory-tracking task that necessitates participants to produce greater hip and knee flexion by coordinating their muscle activation patterns during the swing phase of the gait, and has been used to promote motor recovery after stroke [23], [24], [25], [26], [27], [28]. Here, we used this functional paradigm to study the extent of interlimb transfer and test whether there is an asymmetry in the amount of transfer between the dominant and the non-dominant legs. We hypothesized that significant improvement in performance would be observed in the transfer leg after training with the other leg, and that this transfer would be asymmetric between the dominant and the nondominant leg.

Section snippets

Participants

Twenty right-legged (as determined by their preferred leg to kick a ball) healthy adults (Age: 22.8 ± 5.8 years, Height: 1.7 ± 0.1 m, Weight: 66 ± 15.9 kg) participated in this study. All participants signed an informed consent document that was approved by the University of Michigan Institutional Review Board.

Experimental protocol

The schematic of the experimental protocol is shown in Fig. 1. Prior to the experiment, participants were randomized into two experimental groups: (1) right-to-left (RL) and (2) left-to-right (LR)

Baseline performance

Exemplar data showing tracking performance of a subject in the RL group during key time points of the experiment are shown in Fig. 3. There were no significant differences in baseline performance (i.e., tracking error) between the training and the transfer leg for both the target-matching with visual feedback (F [1], [18] = 0.047, p = 0.831) and no visual feedback conditions (F [1], [18] = 0.5, p = 0.489). There were also no significant group (TM: F [1], [18] = 1.098, p = 0.308; NVF: F [1], [18] = 0.387, p = 

Discussion

In this study, we tested the amount of interlimb transfer during walking and evaluated whether this transfer was asymmetric—i.e., transfer occurred to a greater extent from one leg to the other than vice versa. Two participant groups (RL and LR) practiced a motor learning task that has been previously used for gait rehabilitation. The RL group trained with their right leg and tested for transfer in their left leg, whereas the LR group trained with their left leg and tested for transfer in their

Conflict of interest

The authors declare no conflicts of interest.

Acknowledgements

This work was supported in part by Grants R03-HD069806 and R01-EB019834 from the National Institutes of Health and grants from the University of Michigan Office of Research and Undergraduate Research Opportunities Program. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Reference (43)

  • R.L. Sainburg et al.

    Interlimb transfer of visuomotor rotations: independence of direction and final position information

    Exp. Brain Res.

    (2002)
  • M.L. Latash

    Mirror writing: learning, transfer, and implications for internal inverse models

    J. Mot. Behav.

    (1999)
  • J.I. Laszlo et al.

    Bilateral transfer in tapping skill in the absence of peripheral information

    J. Mot. Behav.

    (1970)
  • T. Bhatt et al.

    Immediate and latent interlimb transfer of gait stability adaptation following repeated exposure to slips

    J. Mot. Behav.

    (2008)
  • T.J. Carroll et al.

    Enhanced crosslimb transfer of force-field learning for dynamics that are identical in extrinsic and joint-based coordinates for both limbs

    J. Neurophysiol.

    (2016)
  • H.Z. Lefumat et al.

    To transfer or not to transfer? Kinematics and laterality quotient predict interlimb transfer of motor learning

    J. Neurophysiol.

    (2015)
  • W.M. Joiner et al.

    The training schedule affects the stability, not the magnitude, of the interlimb transfer of learned dynamics

    J. Neurophysiol.

    (2013)
  • J. Wang et al.

    Aging reduces asymmetries in interlimb transfer of visuomotor adaptation

    Exp. Brain Res.

    (2011)
  • E.A. Pereira et al.

    Effect of training on interlimb transfer of dexterity skills in healthy adults

    Am. J. Phys. Med. Rehabil.

    (2011)
  • T. Bhatt et al.

    Role of cognition and priming in interlimb generalization of adaptive control of gait stability

    J. Mot. Behav.

    (2009)
  • R.E. Hicks

    Asymmetry of bilateral transfer

    Am. J. Psychol.

    (1974)
  • Cited by (19)

    • Learning and interlimb transfer of new gait patterns are facilitated by distributed practice across days

      2019, Gait and Posture
      Citation Excerpt :

      Motor performance during the target-matching task was evaluated by computing the tracking error (i.e., the error between the actual trajectory and the target trajectory) during each training block. Tracking error was computed for each stride in the training block by calculating the difference in area (computed in pixels) between the actual and target trajectory and normalizing it to the area of the target-template trajectory (also computed in pixels) (Fig. 2C) [7,10,15]. The error for each stride was then averaged across all strides in a block to determine the average tracking-error during each training block.

    • Learning new gait patterns: Age-related differences in skill acquisition and interlimb transfer

      2018, Experimental Gerontology
      Citation Excerpt :

      The age criterion for the older adults was 60–75 years, while young adults were eligible if aged between 18 and 35 years. All participants were right leg dominant as determined by their preferred leg for kicking a ball (Krishnan et al., 2017). Participants with a major lower extremity injury or surgery (e.g., joint replacement), history of neurological disorder, or significant cardiac conditions were excluded from the study.

    • Contralateral limb foot rotation during unilateral toe-in or toe-out walking in people with knee osteoarthritis

      2018, Gait and Posture
      Citation Excerpt :

      These modifications are typically applied to a single limb [4,5]. Some transfer of modified motor patterning to the untrained (i.e. contralateral) limb has been found following unilateral training during tasks such as obstacle avoidance or slip testing [6–8]. However, little is known regarding the movement patterns of the contralateral limb during the actual training of the target limb.

    View all citing articles on Scopus
    View full text