The Effect of Rhythm Abilities on Metronome-Cued Walking with an Induced Temporal Gait Asymmetry in Neurotypical Adults.

ABSRACT. Human gait is inherently rhythmical, thus walking to rhythmic auditory stimulation is a promising intervention to improve temporal gait asymmetry (TGA) following neurologic injury such as stroke. However, the degree of benefit may relate to an individual's underlying rhythmic ability. We conducted an initial investigation into the relationship between rhythm abilities and responsiveness of TGA when walking to a metronome. TGA was induced in neurotypical young adults with ankle and thigh cuff weights. Participants were grouped by strong or weak rhythm ability based on beat perception and production tests. TGA was induced using a unilateral load affixed to the non-dominant leg. Participants walked under three conditions: uncued baseline, metronome set to 100% of baseline cadence, and metronome set to 90% of baseline cadence. Repeated measures analysis using generalized estimating equations was conducted to determine how rhythm ability affected TGA response in each walking condition. Most participants improved TGA when walking to a metronome at either tempo compared to baseline; however, this improvement did not differ between strong and weak rhythm ability groups. Those who scored worse on the rhythm perception test also were poorer at synchronizing their steps to the beat. The induced TGA is smaller than what is commonly experienced after stroke. A larger induced TGA may be necessary to reveal subtle differences in responsiveness to rhythmical auditory stimulation between those with strong and weak rhythm abilities.

Study Paradigms and Principles Investigated in Motor Learning Research After Stroke: A Scoping Review.

OBJECTIVES: To (1) characterize study paradigms used to investigate motor learning (ML) poststroke and (2) summarize the effects of different ML principles in promoting skill acquisition and retention. Our secondary objective is to evaluate the clinical utility of ML principles on stroke rehabilitation. DATA SOURCES: Medline, Excerpta Medica Database, Allied and Complementary Medicine, Cumulative Index to Nursing and Allied Health Literature, and Cochrane Central Register of Controlled Trials were searched from inception on October 24, 2018 and repeated on June 23, 2020. Scopus was searched on January 24, 2019 and July 22, 2020 to identify additional studies. STUDY SELECTION: Our search included keywords and concepts to represent stroke and "motor learning. An iterative process was used to generate study selection criteria. Three authors independently completed title, abstract, and full-text screening. DATA EXTRACTION: Three reviewers independently completed data extraction. DATA SYNTHESIS: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension guidelines for scoping reviews were used to guide our synthesis. Thirty-nine studies were included. Study designs were heterogeneous, including variability in tasks practiced, acquisition parameters, and retention intervals. ML principles investigated included practice complexity, feedback, motor imagery, mental practice, action observation, implicit and explicit information, aerobic exercise, and neurostimulation. An additional 2 patient-related factors that influence ML were included: stroke characteristics and sleep. Practice complexity, feedback, and mental practice/action observation most consistently promoted ML, while provision of explicit information and more severe strokes were detrimental to ML. Other factors (ie, sleep, practice structure, aerobic exercise, neurostimulation) had a less clear influence on learning. CONCLUSIONS: Improved consistency of reporting in ML studies is needed to improve study comparability and facilitate meta-analyses to better understand the influence of ML principles on learning poststroke. Knowledge of ML principles and patient-related factors that influence ML, with clinical judgment can guide neurologic rehabilitation delivery to improve patient motor outcomes.

Perceptions of an over-ground induced temporal gait asymmetry by healthy young adults.

Nearly 60% of individuals with stroke walk with temporal gait asymmetry (TGA; a phase inequality between the legs during gait). About half of individuals with TGA are unable to correctly identify the presence or direction of their asymmetry. If patients are unable to perceive their gait errors, it will be harder to correct them to improve their gait pattern. Perception of gait pattern error may be affected by the stroke itself; therefore, the objectives of this study were to determine how the gait of neurotypical individuals changes with an induced temporal asymmetry, and how perception of that TGA compares to actual asymmetry both before and after 15-min of exposure to the induced asymmetry. After baseline symmetry (measured as symmetry index (SI)) was assessed with a pressure sensitive mat, participants (n = 29) walked for 15 min over-ground with cuff weights (7.5% of body weight) on their non-dominant leg to induce TGA. Presence, direction, and magnitude of TGA was measured at five time points: 1) baseline, 2) immediately after unilateral loading (early adaptation (EA)), 3) at the end of 15 min of walking (late adaptation (LA)), 4) immediately after load removal (early deadaptation (EDA)), and 5) after the participant indicated that their gait had returned to baseline symmetry (late deadaptation (LDA). Presence, direction, and magnitude of perceived TGA was measured by self-report. Measured and perceived TGA changes over time were assessed with separate one-way repeated measures analyses of variance. Agreement between measured and perceived TGA was assessed. During EA, all participants walked asymmetrically, spending more time on the non-loaded limb compared to baseline (-12.67 [95%CI -14.56, -10.78], p < 0.0001). All but one participant perceived this TGA, however only fifteen (52%) correctly perceived both TGA presence and direction. At LA, the group remained asymmetric (-9.22 [95%CI -11.32, -7.12], p < 0.0001), but only 9 participants (31%) correctly perceived both the presence and direction of their TGA. Visual inspection of the data at each time point revealed most participants perceived TGA magnitude as greater than actual TGA. Overall, we find that TGA can be induced and maintained in neurotypical young adults. Perception of TGA direction is inaccurate and perception of TGA magnitude is grossly overestimated. Perceptions of TGA do not improve after a period of exposure to the new walking pattern. These preliminary findings indicate that accurately perceiving an altered gait pattern is a difficult task even for healthy young adults.

An Initial Investigation of the Responsiveness of Temporal Gait Asymmetry to Rhythmic Auditory Stimulation and the Relationship to Rhythm Ability Following Stroke.

Temporal gait asymmetry (TGA) is a persistent post-stroke gait deficit. Compared to conventional gait training techniques, rhythmic auditory stimulation (RAS; i.e., walking to a metronome) has demonstrated positive effects on post-stroke TGA. Responsiveness of TGA to RAS may be related to several factors including motor impairment, time post-stroke, and individual rhythm abilities. The purpose of this study was to investigate the relationship between rhythm abilities and responsiveness of TGA when walking to RAS. Assessed using behavioral tests of beat perception and production, participants with post-stroke TGA (measured as single limb support time ratio) were categorized according to rhythm ability (as strong or weak beat perceivers/producers). We assessed change in TGA between walking without cues (baseline) and walking while synchronizing footsteps with metronome cues. Most individuals with stroke were able to maintain or improve TGA with a single session of RAS. Within-group analyses revealed a difference between strong and weak rhythm ability groups. Strong beat perceivers and producers showed significant reduction (improvement) in TGA with the metronome. Those with weak ability did not and exhibited high variability in the TGA response to metronome. Moreover, individuals who worsened in TGA when walking to metronome had poorer beat production scores than those who did not change in TGA. However, no interaction between TGA improvement when walking to metronome and rhythm perception or production ability was found. While responsiveness of TGA to RAS did not significantly differ based on strength of rhythm abilities, these preliminary findings highlight rhythm ability as a potential consideration when treating post-stroke individuals with rhythm-based treatments.

Lower limb muscle activity underlying temporal gait asymmetry post-stroke.

OBJECTIVE: Asymmetric walking after stroke is common, detrimental, and difficult to treat, but current knowledge of underlying physiological mechanisms is limited. This study investigated electromyographic (EMG) features of temporal gait asymmetry (TGA). METHODS: Participants post-stroke with or without TGA and control adults (n = 27, 8, and 9, respectively) performed self-paced overground gait trials. EMG, force plate, and motion capture data were collected. Lower limb muscle activity was compared across groups and sides (more/less affected). RESULTS: Significant group by side interaction effects were found: more affected plantarflexor stance activity ended early (p = .0006) and less affected dorsiflexor on/off time was delayed (p < .01) in persons with asymmetry compared to symmetric and normative controls. The TGA group exhibited fewer dorsiflexor bursts during swing (p = .0009). CONCLUSIONS: Temporal patterns of muscular activation, particularly about the ankle around the stance-to-swing transition period, are associated with TGA. The results may reflect specific impairments or compensations that affect locomotor coordination. SIGNIFICANCE: Neuromuscular underpinnings of spatiotemporal asymmetry have not been previously characterized. These novel findings may inform targeted therapeutic strategies to improve gait quality after stroke.

A novel bilateral lower extremity mirror therapy intervention for individuals with stroke.

Despite improvements made in stroke rehabilitation, motor impairment and gait deficits persist at discharge. New interventions are needed. Mirror therapy has promise as one element of a rehabilitation program. The primary objectives were to 1) describe a bilateral, lower extremity mirror therapy (LE-MT) device and training protocol and 2) investigate the feasibility of LE-MT. A LE-MT device was constructed to train bilateral LE movements for 30 min, 3 times/week for 4 weeks, as an adjunct to physiotherapy in three individuals post-stroke. Sessions were digitally recorded and reviewed to extract feasibility measures; repetitions, rests and session duration. Pre and post measures of gait and motor impairment were taken. Two participants completed 100% of the sessions and a third completed 83% due to a recurrence of pre-existing back pain. Repetitions increased and session duration was maintained. Number of rests decreased for two participants and increased for one participant. Participants reported fatigue and mild muscle soreness but also that the intervention was tolerable. Positive gait changes included increased velocity and decreased variability. LE motor impairment also improved. A bilateral LE-MT adjunct intervention for stroke is feasible and may have positive effects. A history of low back pain should be a precaution.

Knee loading patterns of the non-paretic and paretic legs during post-stroke gait.

BACKGROUND: Post-stoke gait disorders could cause secondary musculoskeletal complications associated with excessive repetitive loading. The study objectives were to 1) determine the feasibility of measuring common proxies for dynamic medial knee joint loading during gait post-stroke with external knee adduction (KAM) and flexion moments (KFM) and 2) characterize knee loading and typical load-reducing compensations post-stroke. METHODS: Participants with stroke (n=9) and healthy individuals (n=17) underwent 3D gait analysis. The stroke and healthy groups were compared with unpaired t-tests on peak KAM and peak KFM and on typical medial knee joint load-reducing compensations; toe out and trunk lean. The relationship between KAM and load-reducing compensations in the stroke group were investigated with Spearman correlations. RESULTS: Mean (SD) values for KAM and KFM in the healthy group[KAM=2.20 (0.88)%BW*ht; KFM=0.64 (0.60)%BW*ht] were not significantly different from the values for the paretic [KAM=2.64 (0.98)%BW*ht; KFM=1.26 (1.13)%BW*ht] or non-paretic leg of the stroke group[KAM=2.23(0.62)%BW*ht; KFM=1.10 (1.20)%BW*ht]. Post hoc one sample t-tests revealed greater loading in stroke participants on the paretic (n=3), non-paretic (n=1) and both legs (n=2) compared to the healthy group. The angle of trunk lean and the angle of toe out were not related to KAM in the stroke group. DISCUSSION: Measurement of limb loading during a gait post-stroke is feasible and revealed excessive loading in individuals with mild to moderate stroke compared to healthy adults. Further investigation of potential joint degeneration and pain due to repetitive excessive loading associated with post-stroke gait is warranted.