Elsevier

Journal of Biomechanics

Volume 83, 23 January 2019, Pages 104-109
Journal of Biomechanics

Walking through the looking glass: Adapting gait patterns with mirror feedback

https://doi.org/10.1016/j.jbiomech.2018.11.029Get rights and content

Abstract

Clinical locomotor research seeks to facilitate adaptation or retention of new walking patterns by providing feedback. Within a split-belt treadmill paradigm, sagittal plane feedback improves adaptation but does not affect retention. Representation of error in this manner is cognitively demanding. However, it is unknown in this paradigm how frontal plane feedback, which may utilize a unique learning process, impacts locomotor adaptation. Frontal plane movement feedback has been shown to impact retention of novel running mechanics but has yet to be evaluated in gait conditions widely applicable within neurorehabilitation, such as walking. The purpose of this study was to investigate the effects of frontal plane mirror feedback on gait adaptation and retention during split-belt treadmill walking. Forty healthy young adults were divided into two groups: one group received mirror feedback during the first split-belt exposure and the other received no mirror feedback. Individuals in the mirror feedback group were asked to look at their legs in the mirror, but no further instructions were given. Individuals with mirror feedback displayed more symmetric stance time during the first strides of adaptation and maintained this pattern into the second split-belt exposure when no feedback was provided. Individuals with mirror feedback also demonstrated more symmetric double support time upon returning to normal walking. Lastly, the mirror feedback also allowed individuals to walk with smaller gait variability during the final steps of both split-belt exposures. Overall, mirror feedback allowed individuals to reduce their stance time asymmetry and led to a more consistent adapted pattern, suggesting this type of feedback may have utility in gait training that targets symmetry and consistency in movement.

Introduction

The ability to adopt and learn new walking patterns is critical for safe and efficient mobility in complex and dynamic environments; still, optimal methods for promoting skill acquisition in walking are not resolved. Learning novel gait mechanics is crucial for gait rehabilitation in patient populations, such as those with hemiplegic gait after a stroke, who need to relearn normal walking. As a result, efforts in locomotor rehabilitation research have focused on understanding factors that facilitate gait adaptation and learning (Balasubramanian et al., 2014, Eng and Tang, 2007, Hollands et al., 2013, Timmermans et al., 2016). Providing feedback is one such factor with the potential to improve the gait rehabilitation process (Eng and Tang, 2007, Hollands et al., 2013, Timmermans et al., 2016).

Models of motor adaptation and learning suggest providing additional feedback of behavior could influence adaptation and retention of a movement (Malone and Bastian, 2010, Newell et al., 2003, Roemmich et al., 2016, Sharma et al., 2016, Willy et al., 2012). For instance, individuals with patellofemoral pain were able to improve their running mechanics when provided a frontal plane mirror image of their body and given verbal cues about their running (Willy et al., 2012). Examining gait adaptability, the split-belt treadmill is an ideal tool for testing the effects of feedback on gait adaptation as it elicits the adjustment of an already learned walking pattern to accommodate novel demands and has demonstrated efficacy in improving walking symmetry after stroke (Reisman et al., 2013, Reisman et al., 2010b, Reisman et al., 2009, Reisman et al., 2007). Previous split-belt treadmill walking studies that manipulated corrective feedback have shown visual feedback (e.g. video projection of the sagittal view of a participant’s lower limbs or visual representation of step lengths) results in faster step length adaptation (Malone and Bastian, 2010, Roemmich et al., 2016), but has no impact on retention (Roemmich et al., 2016). Visual feedback of the sagittal plane provides an indication that an error has occurred (e.g. step lengths are different between legs), but may influence only certain aspects of gait adaptation.

Corrective/instructive feedback is a critical component of motor learning paradigms with the nature of feedback lying within the continuum between explicit and implicit motor learning. Explicit motor learning generates verbal knowledge of movement performance, involves cognitive processes and is dependent on working memory, whereas implicit learning progresses with no or minimal increase in verbal knowledge of movement performance and without awareness (Kleynen et al., 2015). Explicit cueing (Won and Jiang, 2015) with direct representation of error likely engages cognitive processes in a way that fails to promote motor learning (Fitts and Posner, 1967), whereas motor skills learned under more implicit conditions (i.e. without declarative knowledge gained from corrective performance feedback) are more stable and resilient to perturbation, such as stress (Hardy et al., 1996, Masters, 1992) and fatigue (Masters et al., 2008, Poolton et al., 2007). Indeed, motor learning protocols that do not rely on cognitive functions may facilitate rehabilitative benefits in populations with gait and cognitive comorbidity, such as individuals post-stroke (Hochstenbach et al., 1998, Lee et al., 1994). Thus, feedback that indirectly provides information about the walking pattern without providing corrective feedback or verbal instruction may facilitate both adaptation and retention of gait patterns.

Mirror feedback in the absence of explicit verbal instruction represents a more implicit motor learning design, capable of providing real-time visual information about locomotor kinematics. Yet there is a gap in evidence regarding the effect of frontal plane mirror feedback on adaptation and retention of outcomes related to gait symmetry and variability. Therefore in this study, we sought to investigate the effects of a real-time clinically feasible form of feedback that gives less direct perception of error during split-belt treadmill walking, but still provides relevant information about gait mechanics (e.g. general coordination) during a primarily sagittal plane perturbation. To accomplish this, we used mirror-based frontal plane visual feedback to provide participants a view of their body mechanics during adaptation to the novel walking paradigm. We hypothesized mirror feedback would reduce the number of steps needed to adapt and mitigate the magnitude of initial asymmetry in response to the perturbation. Additionally, because this visual plane provides less overt representation of error while still enhancing sensory information, we hypothesized feedback would also enhance retention and reduce the variability of the adapted pattern on the split-belt treadmill.

Section snippets

Subjects

Forty healthy young adults [18 males, 22 females, age (mean ± SD) 21 ± 3 years, height 1.7 ± 0.1 m, mass 67.3 ± 11.6 kg, 5 ± 2 h/week physical activity] naïve to the split-belt treadmill volunteered to participate. At the time of recruitment, all subjects were physically active as defined by participation in a minimum of 30 min of physical activity at least two times per week. Participants were excluded if they were currently injured or suffered an injury within the last six months that limited

Results

Demographic data (age, mass, height, and physical activity level) were not statistically different between groups (P > 0.60).

Discussion

Corrective feedback can vary in degree of implicit or explicit information provided to the individual (i.e. overtness of the indication that an error exists). The impact of this distinction has been investigated in many domains, such as dynamic balance (Orrell et al., 2006, Shea et al., 2001) and visuomotor adaptation (McDougle et al., 2015, Taylor et al., 2014). Within the realm of split-belt treadmill walking, feedback that directly represents error has been shown to accelerate adaptation (

Acknowledgements

The authors would like to thank all laboratory students, particularly Devan Ludden, for their help with data collection and processing and all volunteers for their participation in this study. The authors would also like to thank Dr. Michael Marsiske for his expertise and assistance with statistical analysis. The authors declare no funding sources.

Conflict of interest statement

The authors declare no conflicts of interest.

References (40)

  • J. Cohen

    Statistical Power Analysis for the Behavioral Sciences

    (1977)
  • J.J. Eng et al.

    Gait training strategies to optimize walking ability in people with stroke: a synthesis of the evidence

    Expert Rev. Neurother.

    (2007)
  • F. Faul et al.

    G*Power 3: a flexible statistical power analysis program for the social, behavioral, and biomedical sciences

    Behav. Res. Methods

    (2007)
  • P.M. Fitts et al.

    Human Performance

    (1967)
  • L. Hardy et al.

    Knowledge and conscious control of motor actions under stress

    Br. J. Psychol. Lond. Engl.

    (1996)
  • J. Hochstenbach et al.

    Cognitive decline following stroke: a comprehensive study of cognitive decline following stroke

    J. Clin. Exp. Neuropsychol.

    (1998)
  • K.L. Hollands et al.

    Visual cue training to improve walking and turning after stroke: a study protocol for a multi-centre, single blind randomised pilot trial

    Trials

    (2013)
  • W. Hoogkamer et al.

    Gait asymmetry during early split-belt walking is related to perception of belt speed difference

    J. Neurophysiol.

    (2015)
  • M. Kleynen et al.

    Multidisciplinary views on applying explicit and implicit motor learning in practice: an international survey

    PLoS ONE

    (2015)
  • T. Lee et al.

    Cognitive effort and motor learning

    Quest

    (1994)
  • Cited by (7)

    • Persons with Parkinson's disease show impaired interlimb coordination during backward walking

      2022, Parkinsonism and Related Disorders
      Citation Excerpt :

      For each combination of limbs (MA/MA, LA/LA, MA/LA, LA/MA), PERP and ROM were evaluated in two separate 2 × 2 (Group × Condition) repeated measures MANOVAs. We used the most stringent level of Median Absolute Deviation method to detect outlying values, as 95% of data should lie within ∼2 deviations of the median if normal [16–18]. In both walking conditions, we identified and replaced outlying PERP values for all combinations of limbs and hip and shoulder ROM values on both sides with two deviations from the median [19].

    • Understanding Human Neural Control of Short-term Gait Adaptation to the Split-belt Treadmill

      2020, Neuroscience
      Citation Excerpt :

      For instance, accurate visual feedback of the gait pattern during split-belt walking reduced asymmetry in late adaptation (Leech et al., 2018). In addition, a mirror placed in frontal plane reduced stance time asymmetry and variability during the later stages of adaptation (Stone et al., 2019). There was, however, no effect of visual feedback on the magnitude of asymmetry during adaptation (Eikema et al., 2016; Leech et al., 2018), even when distorted from proprioceptive information (Chunduru et al., 2019).

    • Unveiling Patterns and Abnormalities of Human Gait: A Comprehensive Study

      2024, Indian Journal of Information Sources and Services
    View all citing articles on Scopus
    View full text