Therapists' cues influence lower limb muscle activation and kinematics during gait training in subacute stroke

A Comparison of the Immediate Effects of Verbal and Virtual Reality Feedback on Gait in Children with Cerebral Palsy

Different types of feedback are used during gait training in children with cerebral palsy (CP), including verbal (VB) and virtual reality (VR) feedback. Previous studies on VR feedback showed positive effects on the targeted gait parameter. However, both positive and negative side effects on other parameters were seen as well. The literature on the effect of VB feedback is lacking and, to our knowledge, both feedback methods have not yet been compared. In this monocentric study with a single-session intervention protocol, children with CP completed a training session on the Gait Real-Time Analysis Interactive Lab (GRAIL) and received both VB and VR feedback on hip extension, in randomized order. Outcome parameters were continuous gait curves of sagittal kinematics and hip kinetics, specific features of hip angle and moment, sagittal gait variable scores and gait profile scores. Improvement of the targeted gait parameter was seen both after VB and VR feedback, with a small advantage for VR over VB feedback. Furthermore, positive side effects on knee and ankle sagittal kinematics were seen. However, the overall gait profile score did not improve, most likely due to negative compensatory strategies. In conclusion, children with CP can adapt gait in response to both VB and VR feedback, with VR feedback producing a slightly better effect. Due to secondary effects on parameters other than the targeted parameter, the overall gait did not improve.

Effects of Verbal and Tactile Cues on Gluteal Force Production and Broad Jump Distance

Background

Verbal and tactile cues can increase muscle activity, force production, and kinematics. Several studies demonstrate the effects of verbal and tactile cues on upper extremity muscles, while relatively few examined lower extremity muscles, specifically the gluteals. Studies that observed changes in gluteal function from verbal and tactile cues examined muscle activity via electromyography rather than force production or functional activities such as jumping.

Purpose

The purpose of this study was to measure the effects of verbal and tactile cues on gluteal force production and broad jump distance.

Study Design

Cross-Sectional cohort.

Methods

Gluteus maximus force production and broad jump distance were tested in forty-two healthy male and female university students at baseline and after verbal and tactile cues given in random order. Gluteus maximus force was measured using handheld dynamometry and reported in kilograms. Verbal cues included "push, push, push" before both tests. The examiner provided tactile cues to the gluteus maximus before force production testing, and the participant provided tactile cues to both gluteus maximus muscles before performing the broad jump. Performance on the broad jump was measured in centimeters. Descriptive statistics and test-retest reliability via Pearson correlation coefficients were calculated, differences in performance between sexes were analyzed with an independent t-test, and changes in force production and jump distance from baseline were analyzed using a one-way ANOVA.

Results

Mean gluteus maximus force production following verbal cues significantly increased (p = 0.000) by 13.48% (3.83 kg) compared to the control condition, while gluteal force production following the tactile cues was not significantly different. Broad jump distance following the verbal cues significantly increased (p = 0.000) 3.99% (7.71 cm) compared to the control condition and significantly increased (p = 0.000) by 2.95% (5.71 cm) following the tactile cues. There were no significant differences in performances between males and females. The test-retest reliability of all measurements was 0.97-0.99.

Conclusion

Verbal cues significantly increased gluteus maximus force production and broad jump distance. Tactile cues significantly increased broad jump distance but had no significant effect on gluteus maximus force. These results have implications for clinical testing and athletic performance when gluteus maximus force and jump distance are concerned.

Level of Evidence

3.

Optimal Blood Flow Restriction Occlusion Pressure for Shoulder Muscle Recruitment With Upper Extremity Exercise

BACKGROUND

As blood flow restriction (BFR) utilization continues to rise, it is crucial to define optimal parameters for use. Currently unknown are the effects of occlusion level during BFR on muscle activity in the proximal shoulder.

PURPOSE/HYPOTHESIS

The purpose of this study was to compare electromyographic amplitude (EMGa) of shoulder musculature during exercise using limb occlusion percentages (LOPs). The authors hypothesized that EMGa would increase concurrently with occlusion.

STUDY DESIGN

Controlled laboratory study.

METHODS

α Fifteen healthy adults were recruited and underwent 4 experimental sessions, performing 3 common rotator cuff exercises at low intensity (20% maximal strength) to failure in the following order: cable external rotation (ER), cable internal rotation (IR), and dumbbell scaption. Exercises were completed at a different occlusion pressure (0%, 25%, 50%, and 75% LOP- order randomized) applied at the proximal arm. EMGa was recorded from shoulder musculature proximal to the occlusion site and averaged across 5-repetition intervals and overall for the first 30 repetitions. An analysis of variance repeated on occlusion pressure followed by a Bonferroni post hoc test was used to compare EMGa, repetitions to fatigue, and ratings of discomfort (visual analog scale [VAS], 0-10) between occlusion pressures. The type 1 error was set at α = .05 for all analyses.

RESULTS

Significant effects of the occlusion level on shoulder muscle EMGa were observed for all exercises (P < .05) with diminishing returns above 50% LOP (overall). For ER, elevations in EMGa were observed at ≥50% LOP for the anterior deltoid, middle deltoid, infraspinatus, and trapezius compared with 0% LOP (P < .05). For IR, elevations in EMGa were observed at ≥25% LOP for the anterior deltoid and trapezius compared with 0% LOP (P < .05). For the teres minor, a significant elevation in EMGa occurred at 75% LOP compared with 0%, 25%, and 50% LOP (P < .05). A decrease in EMGa was observed at ≥50% LOP compared with 0% LOP for the posterior deltoid (P < .05). For scaption, an increase in EMGa was observed at ≥25% LOP for the infraspinatus and teres minor muscles, at 75% LOP for the posterior deltoid, and at ≥50% LOP for the trapezius compared with 0% LOP (P < .05). Decreases in repetitions to failure relative to 0% LOP were observed at 75% LOP for ER (0%: 47 ± 5; 75%: 40 ± 2; P = .034), IR (0%: 82 ± 10; 75%: 64 ± 5; P = .017), and scaption (0%: 85 ± 9; 75%: 64 ± 6; P < .001). A significant linear increase in discomfort was observed for all exercises with increasing occlusion pressures (VAS: 0-10, 0% → 75% LOP; ER: 2.2 ± 0.4 → 7.2 ± 0.3; IR: 1.3 ± 0.2 → 6.1 ± 0.6; scaption: 1.3 ± 0.4 → 6.1 ± 0.4; P < .01).

CONCLUSION

There are several differences in muscle activation about the shoulder based on exercise and occlusion when utilizing BFR. Increasing the percentage of limb occlusion leads to heightened EMGa with diminished returns past 50% LOP when considering muscle activation, discomfort, and achievable exercise volume.

CLINICAL RELEVANCE

These findings may be used to refine upper extremity BFR guidelines.

Adjunct Non-Elastic Hip Taping Improves Gait Stability in Cane-Assisted Individuals with Chronic Stroke: A Randomized Controlled Trial

Cane-assisted individuals with chronic stroke may perform with an abnormal gait pattern. One of the important factors of gait training for cane-assisted individuals is inducing improvement in lower limb muscle activity of the paretic side. Non-elastic taping on the hip may be used as an adjunct therapy for improving gait. The objective of this study was to investigate effects of non-elastic hip taping combined with exercise on gait in cane-assisted individuals with chronic stroke. This study is a single-blinded, randomized controlled trial. A total of 21 cane-assisted ambulators with chronic stroke were enrolled. Participants in both groups received a therapeutic exercise program, with the experimental and control groups having adjunct non-elastic taping and sham taping on the hip, respectively. The gait, Berg Balance Scale, 6-min walk test, and Fall Efficacy Scale–International were measured at pre-intervention, post-intervention, and 1-month follow-up. The experimental group resulted in significantly better performance in double-support time compared with the control group. Furthermore, the experimental group showed a significant improvement in double-support time and spatial symmetry at post-intervention and 1-month follow-up compared with pre-intervention. This study demonstrated that non-elastic hip taping combined with exercise could improve gait stability in cane-assisted ambulators. Non-elastic hip taping would be a useful adjunct to rehabilitation strategies for individuals with chronic stroke.

Blood Flow Restriction Enhances Rehabilitation and Return to Sport: The Paradox of Proximal Performance

The use of blood flow restriction (BFR) within rehabilitation is rapidly increasing as further research is performed elucidating purported benefits such as improved muscular strength and size, neuromuscular control, decreased pain, and increased bone mineral density. Interestingly, these benefits are not isolated to structures distal to the occlusive stimulus. Proximal gains are of high interest to rehabilitation professionals, especially those working with patients who are limited due to pain or postsurgical precautions. The review to follow will focus on current evidence and ongoing hypotheses regarding physiologic responses to BFR, current clinical applications, proximal responses to BFR training, potential practical applications for rehabilitation and injury prevention, and directions for future research. Interestingly, benefits have been found in musculature proximal to the occlusive stimulus, which may lend promise to a greater variety of patient populations and conditions. Furthermore, an increasing demand for BFR use in the sports world warrants further research for performance research and recovery.

LEVEL OF EVIDENCE

Level V, expert opinion.

Blood Flow Restriction Training for the Shoulder: A Case for Proximal Benefit

BACKGROUND

Although blood flow restriction (BFR) is becoming increasingly popular in physical therapy and athletic training settings, little is known about the effects of BFR combined with low-intensity exercise (LIX) on muscles proximal to the site of occlusion.

HYPOTHESIS/PURPOSE

Determine whether LIX combined with BFR applied distally to the shoulder on the brachial region of the arm (BFR-LIX) promotes greater increases in shoulder lean mass, rotator cuff strength, endurance, and acute increases in shoulder muscle activation compared with LIX alone. We hypothesized that BFR-LIX would elicit greater increases in rotator cuff strength, endurance, and muscle mass. We also hypothesized that the application of BFR would increase EMG amplitude in the shoulder muscles during acute exercise.

STUDY DESIGN

Controlled laboratory study.

METHODS

32 healthy adults were randomized into 2 groups (BFR group, 13 men, 3 women; No-BFR group, 10 men, 6 women) who performed 8 weeks of shoulder LIX (2 times per week; 4 sets [30/15/15/fatigue]; 20% maximum) using common rotator cuff exercises (cable external rotation [ER], cable internal rotation [IR], dumbbell scaption, and side-lying dumbbell ER). The BFR group also trained with an automated tourniquet placed at the proximal arm (50% occlusion). Regional lean mass (dual-energy x-ray absorptiometry), isometric strength, and muscular endurance (repetitions to fatigue [RTF]; 20% maximum; with and without 50% occlusion) were measured before and after training. Electromyographic amplitude (EMGa) was recorded from target shoulder muscles during endurance testing. A mixed-model analysis of covariance (covaried on baseline measures) was used to detect within-group and between-group differences in primary outcome measures (α = .05).

RESULTS

The BFR group had greater increases in lean mass in the arm (mean ± 95% CI: BFR, 175 ± 54 g; No BFR, -17 ± 77 g; P < .01) and shoulder (mean ± 95% CI: BFR, 278 ± 90 g; No BFR, 96 ± 61 g; P < .01), isometric IR strength (mean ± 95% CI: BFR, 2.9 ± 1.3 kg; No BFR, 0.1 ± 1.3 kg; P < .01), single-set RTF volume (repetitions × resistance) for IR (~1.7- to 2.1-fold higher; P < .01), and weekly training volume (weeks 4, 6-8, ~5%-22%; P < .05). Acute occlusion (independent of group or timepoint) yielded increases in EMGa during RTF (~10%-20%; P < .05).

CONCLUSION

Combined BFR-LIX may yield greater increases in shoulder and arm lean mass, strength, and muscular endurance compared with fatiguing LIX alone during rotator cuff exercises. These findings may be due, in part, to a greater activation of shoulder muscles while using BFR.

CLINICAL RELEVANCE

The present study demonstrates that BFR-LIX may be a suitable candidate for augmenting preventive training or rehabilitation outcomes for the shoulder.

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.

Targeted verbal cues can immediately alter gait following stroke

Background: Physical therapists use verbal cueing extensively during gait rehabilitation. Nevertheless, little is known about the ability of individuals post-stroke to make immediate changes to targeted spatiotemporal gait parameters from verbal commands. Additionally, adequate muscle strength may be necessary to promote positive alterations in gait.Objectives: To determine the influence of targeted verbal cues on spatiotemporal gait parameters for individuals with chronic stroke. Further, we assessed the potential of a relationship between cue-induced gait modifications and paretic lower limb strength.Methods: Using a within-subjects design, twenty-seven adults with chronic stroke walked over a pressure mat with verbal cues to walk at (1) comfortable and (2) fast speeds, with increased (3) arm swing, (4) foot height, (5) step length, (6) push off, and (7) cadence. We also assessed lower extremity strength using a hand-held dynamometer. We measured gait speed, step length, stance time, and cadence for comparisons between conditions and performed correlational analyses to assess the influence of strength on gait alterations.Results: Specific cues elicited increased walking speed, cadence, step lengths and paretic limb stance time. Only greater paretic hip and knee flexion strength was related to the ability to increase cadence when cued to do so (r > 0.41).Conclusion: With targeted verbal cueing, clinicians can improve step length, gait speed, stance time and cadence for individuals with chronic stroke. Lower extremity strength does not appear to be related to the ability to alter gait with verbal cueing in individuals with chronic stroke.

AI Therapist Realizing Expert Verbal Cues for Effective Robot-Assisted Gait Training

Repetitive and specific verbal cues by a therapist are essential in aiding a patient's motivation and improving the motor learning process. The verbal cues comprise various expressions, sentences, volumes, and timings, depending on the therapist's proficiency. This paper proposes an AI therapist (AI-T) that implements the verbal cues of professional therapists having extensive experience with robot-assisted gait training using the SUBAR for stroke patients. The AI-T was developed using a neuro-fuzzy system, a machine learning technique leveraging the benefits of fuzzy logic and artificial neural networks. The AI-T was trained with the professional therapist's verbal cue data, as well as clinical and robotic data collected from robot-assisted gait training with real stroke patients. Ten clinical data and 16 robotic data are input variables, and six verbal cues are output variables. Fifty-eight stroke patients wore the SUBAR, a gait training robot, and participated in the robot-assisted gait training. A total of 9059 verbal cue data, 580 clinical data of stroke patients, and 144 944 robotic data were collected from 693 training sessions. Test results show that the trained AI-T can implement six types of verbal cues with 93.7% accuracy for the 1812 verbal cue data of the professional therapist. Currently, the trained AI-T is deployed in the SUBAR and provides six verbal cues to stroke patients in robot-assisted gait training.

EEG Changes in Time and Time-Frequency Domain During Movement Preparation and Execution in Stroke Patients

This study investigated electroencephalogram (EEG) changes during movement preparation and execution in stroke patients. EEG-based event-related potential (ERP) technology was used to measure brain activity changes. Seventeen stroke patients participated in this study and completed ERP tests that were designed to measure EEG changes during unilateral upper limb movements in preparation and execution stages, with Instruction Response Movement (IRM) and Cued Instruction Response Movement (CIRM) paradigms. EEG data were analyzed using motor potential (MP) in the time domain and the mu-rhythm and beta frequency band response mean value (R-means) in the time-frequency domain. In IRM, the MP amplitude at Cz was higher during hemiplegic arm movement than during unaffected arm movement. MP latency was shorter at Cz and the contralesional motor cortex during hemiplegic arm movement in CIRM compared to IRM. No significant differences were found in R-means among locations, between movement sides in both ERP tests. This study presents the brain activity changes in the time and time-frequency domains in stroke patients during movement preparation and execution and supports the contralesional compensation and adjacent-region compensation mechanism of post-stroke brain reconstruction. These findings may contribute to future rehabilitation research about neuroplasticity and technology development such as the brain-computer interface.

Individualized feedback to change multiple gait deficits in chronic stroke

Background

Walking deficits in people post-stroke are often multiple and idiosyncratic in nature. Limited patient and therapist resources necessitate prioritization of deficits such that some may be left unaddressed. More efficient delivery of therapy may alleviate this challenge. Here, we look to determine the utility of a novel principal component-based visual feedback system that targets multiple, patient-specific features of gait in people post-stroke.

Methods

Ten individuals with stroke received two sessions of visual feedback to attain a walking goal. This goal consisted of bilateral knee and hip joint angles of a typical ‘healthy’ walking pattern. The feedback system uses principal component analysis (PCA) to algorithmically weight each of the input features so that participants received one stream of performance feedback. In the first session, participants had to explore different patterns to achieve the goal, and in the second session they were informed of the goal walking pattern. Ten healthy, age-matched individuals received the same paradigm, but with a hemiparetic goal (i.e. to produce the pattern of an exemplar stroke participant). This was to distinguish the extent to which performance limitations in stroke were due neurological injury or the PCA based visual feedback itself.

Results

Principal component-based visual feedback can differentially bias multiple features of walking toward a prescribed goal. On average, individuals with stroke typically improved performance via increased paretic knee and hip flexion, and did not perform better with explicit instruction. In contrast, healthy people performed better (i.e. could produce the desired exemplar stroke pattern) in both sessions, and were best with explicit instruction. Importantly, the feedback for stroke participants accommodated a heterogeneous set of walking deficits by individually weighting each feature based on baseline walking.

Conclusions

People with and without stroke are able to use this novel visual feedback to train multiple, specific features of gait. Important for stroke, the PCA feedback allowed for targeting of patient-specific deficits. This feedback is flexible to any feature of walking in any plane of movement, thus providing a potential tool for therapists to simultaneously target multiple aberrant features of gait.