Increases in muscle activity produced by vibration of the thigh muscles during locomotion in chronic human spinal cord injury

Development and deployment of cyclical focal muscle vibration system to improve walking performance in multiple sclerosis

Vibration, a potent mechanical stimulus for activating muscle spindle primary afferents, may improve gait performance in persons with multiple sclerosis (MS), but has yet to be developed and deployed for multiple leg muscles with application during walking training. This study explored the development of a cyclic focal muscle vibration (FMV) system, and the deployment feasibility to correct MS walking swing phase deficits in order to determine whether this intervention warrants comprehensive study. The system was deployed during twelve, two-hour sessions of walking with cyclic FMV over six weeks. Participants served as their own control. Blood pressure, heart rate, walking speed, kinematics (peak hip, knee and ankle angles during swing), toe clearance, and step length were measured before and after deployment with blood pressure and heart rate monitored during deployment. During system deployment, there were no untoward sensations and physiological changes in blood pressure and heart rate, and volitional improvements were found in walking speed, improved swing phase kinematics, toe clearance and step length. This FMV training system was developed and deployed to improve joint flexion during walking in those with MS, and it demonstrated feasibility and benefits. Further study will determine the most effective vibration frequency and dose, carryover effects, and those most likely to benefit from this intervention.

The use of surface EMG in neurorehabilitation following traumatic spinal cord injury: A scoping review

OBJECTIVE

Surface electromyography (sEMG) is a common electrophysiological assessment used in clinical trials in individuals with spinal cord injury (SCI). This scoping review summarizes the most common sEMG techniques used to address clinically relevant neurorehabilitation questions. We focused on the role of sEMG assessments in the clinical practice and research studies on neurorehabilitation after SCI, and how sEMG reflects the changes observed with rehabilitation. Additionally, this review emphasizes the limitations and pitfalls of the sEMG assessments in the field of neurorehabilitation after SCI.

METHODS

A comprehensive search of Medline (Ovid), Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Embase, Emcare, Cumulative Index to Nursing & Allied Health Literature, and PubMed was conducted to find peer-reviewed journal articles that included individuals post-SCI that participated in neurorehabilitation interventions using sEMG assessments. This is a scoping review using a systematic search (hybrid review).

RESULTS

Of 4522 references captured in the primary database searches, 100 references were selected and included in the scoping review. The main focus of the studies was on neurorehabilitation using sEMG biofeedback, brain stimulation, locomotor training, neuromuscular electrical stimulation (NMES), paired-pulse stimulation, pharmacology, posture and balance training, spinal cord stimulation, upper limb training, vibration, and photobiomodulation.

CONCLUSIONS

Most studies employed sEMG amplitude to understand the effects of neurorehabilitation on muscle activation during volitional efforts or reduction of spontaneous muscle activity (e.g., spasms, spasticity, and hypertonia). Further studies are needed to understand the long-term reliability of sEMG amplitude, to circumvent normalization issues, and to provide a deeper physiological background to the different sEMG analyses.

SIGNIFICANCE

This scoping review reveals the potential of sEMG in exploring promising neurorehabilitation strategies following SCI and discusses the barriers limiting its widespread use in the clinic.

Properties of the surface electromyogram following traumatic spinal cord injury: a scoping review

Traumatic spinal cord injury (SCI) disrupts spinal and supraspinal pathways, and this process is reflected in changes in surface electromyography (sEMG). sEMG is an informative complement to current clinical testing and can capture the residual motor command in great detail-including in muscles below the level of injury with seemingly absent motor activities. In this comprehensive review, we sought to describe how the sEMG properties are changed after SCI. We conducted a systematic literature search followed by a narrative review focusing on sEMG analysis techniques and signal properties post-SCI. We found that early reports were mostly focused on the qualitative analysis of sEMG patterns and evolved to semi-quantitative scores and a more detailed amplitude-based quantification. Nonetheless, recent studies are still constrained to an amplitude-based analysis of the sEMG, and there are opportunities to more broadly characterize the time- and frequency-domain properties of the signal as well as to take fuller advantage of high-density EMG techniques. We recommend the incorporation of a broader range of signal properties into the neurophysiological assessment post-SCI and the development of a greater understanding of the relation between these sEMG properties and underlying physiology. Enhanced sEMG analysis could contribute to a more complete description of the effects of SCI on upper and lower motor neuron function and their interactions, and also assist in understanding the mechanisms of change following neuromodulation or exercise therapy.

Reaching exercise for chronic paretic upper extremity after stroke using a novel rehabilitation robot with arm-weight support and concomitant electrical stimulation and vibration: before-and-after feasibility trial

Background

Our group developed a rehabilitation robot to assist with repetitive, active reaching movement of a paretic upper extremity. The robot is equipped with a servo motor-controlled arm-weight support and works in conjunction with neuromuscular electrical stimulation and vibratory stimulation to facilitate agonist-muscle contraction. In this before-and-after pilot study, we assessed the feasibility of applying the robot to improve motor control and function of the hemiparetic upper extremity in patients who suffered chronic stroke.

Methods

We enrolled 6 patients with chronic stroke and hemiparesis who, while sitting and without assistance, could reach 10 cm both sagitally and vertically (from a starting position located 10 cm forward from the patient’s navel level) with the affected upper extremity. The patients were assigned to receive reaching exercise intervention with the robot (Yaskawa Electric Co., Ltd. Fukuoka, Japan) for 2 weeks at 15 min/day in addition to regular occupational therapy for 40 min/day. Outcomes assessed before and after 2 weeks of intervention included the upper extremity component of the Fugl-Meyer Assessment (UE-FMA), the Action Research Arm Test (ARAT), and, during reaching movement, kinematic analysis.

Results

None of the patients experienced adverse events. The mean score of UE-FMA increased from 44.8 [SD 14.4] to 48.0 [SD 14.4] (p = 0.026, r = 0.91), and both the shoulder–elbow and wrist–hand scores increased after 2-week intervention. An increase was also observed in ARAT score, from mean 29.8 [SD 16.3] to 36.2 [SD 18.1] (p = 0.042, r = 0.83). Kinematic analysis during the reaching movement revealed a significant increase in active range of motion (AROM) at the elbow, and movement time tended to decrease. Furthermore, trajectory length for the wrist (“hand path”) and the acromion (“trunk compensatory movement”) showed a decreasing trend.

Conclusions

This robot-assisted modality is feasible and our preliminary findings suggest it improved motor control and motor function of the hemiparetic upper extremity in patients with chronic stroke. Training with this robot might induce greater AROM for the elbow and decrease compensatory trunk movement, thus contributing to movement efficacy and efficiency.

Trial registration UMIN Clinical Trial Registry, as UMIN000018132, on June 30, 2015. https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000020398

Electrophysiological Outcome Measures in Spinal Cord Injury Clinical Trials: A Systematic Review

Background: Electrophysiological measures are being increasingly utilized due to their ability to provide objective measurements with minimal bias and to detect subtle changes with quantitative data on neural function. Heterogeneous reporting of trial outcomes limits effective interstudy comparison and optimization of treatment. Objective: The objective of this systematic review is to describe the reporting of electrophysiological outcome measures in spinal cord injury (SCI) clinical trials in order to inform a subsequent consensus study. Methods: A systematic search of PubMed and EMBASE databases was conducted according to PRISMA guidelines. Adult human SCI clinical trials published in English between January 1, 2008 and September 15, 2018 with at least one electrophysiological outcome measure were eligible. Findings were reviewed by all authors to create a synthesis narrative describing each outcome measure. Results: Sixty-four SCI clinical trials were included in this review. Identified electrophysiological outcomes included electromyography activity (44%), motor evoked potentials (33%), somatosensory evoked potentials (33%), H-reflex (20%), reflex electromyography activity (11%), nerve conduction studies (9%), silent period (3%), contact heat evoked potentials (2%), and sympathetic skin response (2%). Heterogeneity was present in regard to both methods of measurement and reporting of electrophysiological outcome measures. Conclusion: This review demonstrates need for the development of a standardized reporting set for electrophysiological outcome measures. Limitations of this review include exclusion of non-English publications, studies more than 10 years old, and an inability to assess methodological quality of primary studies due to a lack of guidelines on reporting of systematic reviews of outcome measures.

The effects of muscle vibration on gait control: a review

Background: The purpose of the review is to summarize the literature surrounding the use of muscle vibration as it relates to modifying human gait. Methods: After a brief introduction concerning historical uses and early research identifying the effect of vibration on muscle activation, we reviewed 32 articles that used muscle vibration during walking. The review is structured to address the literature within four broad categories: the effect of vibration to 'trigger' gait-like lower limb motions, the effect of vibration on gait control of healthy individuals and individuals with clinical conditions in which gait disorders are a prominent feature, and the effect of vibration training protocols on gait. Results: The acute effects of vibration during gait involving healthy participants is varied. Some authors reported differences in segmental kinematic and spatiotemporal measures while other authors reported no differences in these outcome measures. The literature involving participants with clinical conditions revealed that vibration consistently had a significant impact on gait, suggesting vibration may be an effective rehabilitation tool. All of the studies that used vibration therapy over time reported significant improvement in gait performance. Conclusions: This review highlights the difficulties in drawing definitive conclusions as to the impact of vibration on gait control, partly because of differences in walking protocols, site of vibration application, and outcome measures used across different investigative teams. It is suggested that the development of common investigative methodologies and outcome measures would accelerate the identification of techniques that may provide optimal rehabilitation protocols for individuals experiencing disordered gait control.

Focal Vibration Stretches Muscle Fibers by Producing Muscle Waves

Focal vibration is an effective intervention for the management of spasticity. However, its neuromechanical effects, particularly how tonic vibration reflex is induced explicitly, remain implicit. In this paper, we utilize a high-speed camera and a method of image processing to quantify the muscle vibration rigorously and disclose the neuromechanical mechanism of focal vibration. The vibration of 75 Hz is applied on the muscle belly of the biceps brachii and muscle responses are captured by a high-speed camera in profile. The muscle silhouettes are identified by the Canny edge detector to represent the stretch of muscle fibers, and the consistency between the muscle stretch and profile deformation has been confirmed by the magnetic resonance imaging in advance. Oscillations of muscle points discretized by pixels are identified by the fast Fourier transformation, respectively, and results demonstrate that focal vibration stretches muscle by producing muscle waves. Specifically, each point vibrates harmonically, and, given the linear phase modulation with transverse position, the muscle vibration propagates as traveling waves. The propagation of muscle waves is associated with muscle stretch, whose frequency is the same with the vibrator due to the curved baseline, and thus induces the tonic vibration reflex via spinal circuits.

Effect of tendon vibration during wide-pulse neuromuscular electrical stimulation (NMES) on muscle force production in people with spinal cord injury (SCI)

Background

Neuromuscular electrical stimulation (NMES) is commonly used in skeletal muscles in people with spinal cord injury (SCI) with the aim of increasing muscle recruitment and thus muscle force production. NMES has been conventionally used in clinical practice as functional electrical stimulation (FES), using low levels of evoked force that cannot optimally stimulate muscular strength and mass improvements, and thus trigger musculoskeletal changes in paralysed muscles. The use of high intensity intermittent NMES training using wide-pulse width and moderate-intensity as a strength training tool could be a promising method to increase muscle force production in people with SCI. However, this type of protocol has not been clinically adopted because it may generate rapid muscle fatigue and thus prevent the performance of repeated high-intensity muscular contractions in paralysed muscles. Moreover, superimposing patellar tendon vibration onto the wide-pulse width NMES has been shown to elicit further increases in impulse or, at least, reduce the rate of fatigue in repeated contractions in able-bodied populations, but there is a lack of evidence to support this argument in people with SCI.

Methods

Nine people with SCI received two NMES protocols with and without superimposing patellar tendon vibration on different days (i.e. STIM and STIM+vib), which consisted of repeated 30 Hz trains of 58 wide-pulse width (1000 μs) symmetric biphasic pulses (0.033-s inter-pulse interval; 2 s stimulation train; 2-s inter-train interval) being delivered to the dominant quadriceps femoris. Starting torque was 20% of maximal doublet-twitch torque and stimulations continued until torque declined to 50% of the starting torque. Total knee extensor impulse was calculated as the primary outcome variable.

Results

Total knee extensor impulse increased in four subjects when patellar tendon vibration was imposed (59.2 ± 15.8%) but decreased in five subjects (− 31.3 ± 25.7%). However, there were no statistically significant differences between these sub-groups or between conditions when the data were pooled.

Conclusions

Based on the present results there is insufficient evidence to conclude that patellar tendon vibration provides a clear benefit to muscle force production or delays muscle fatigue during wide-pulse width, moderate-intensity NMES in people with SCI.

Trial registration

ACTRN12618000022268. Date: 11/01/2018. Retrospectively registered.

RCVibro System: full description of a custom-made vibratory system and its reliability

BACKGROUND

The use of local muscle vibration is a promising technique to improve motor performance in people with movement impairments. Majority of studies have failed to properly describe the used system and its reliability, making it difficult to transfer this promising technique to clinical practice.

OBJECTIVE

To describe technical details of a custom-made vibratory system (RCVibro System), as well as to determine its reliability and functionality.

METHODS

The vibration frequency and the electric potential difference/vibration frequency curve of six devices were assessed (at the same day and at different days), allowing us to determine the system reliability. In addition, the RCVibro System functionality was analyzed by the center-of-pressure behavior assessment during the tibialis anterior bilateral stimulation in fifteen young people.

RESULTS

The RCVibro System showed a very-high reliability between assessments within the same day (ICC_(2,6) ranging from 0.95 to 0.99; p<0.01) and between different days (ICC_(2,6) ranging from 0.81 to 0.98; p<0.01). We also observed a forward center-of-pressure displacement (p<0.01) and an increase in the center-of-pressure velocity (p<0.01).

CONCLUSION

We conclude that RCVibro System is a highly reliable system. The results demonstrate the potential usage of RCVibro System in clinical and research settings. Further investigation is needed in people with motor and neurological disorders.

Effect of tendon vibration during wide-pulse neuromuscular electrical stimulation (NMES) on the decline and recovery of muscle force

BACKGROUND

Neuromuscular electrical stimulation (NMES) is commonly used to activate skeletal muscles and reverse muscle atrophy in clinical populations. Clinical recommendations for NMES suggest the use of short pulse widths (100-200 μs) and low-to-moderate pulse frequencies (30-50 Hz). However, this type of NMES causes rapid muscle fatigue due to the (non-physiological) high stimulation intensities and non-orderly recruitment of motor units. The use of both wide pulse widths (1000 μs) and tendon vibration might optimize motor unit activation through spinal reflex pathways and thus delay the onset of muscle fatigue, increasing muscle force and mass. Thus, the objective of this study was to examine the acute effects of patellar tendon vibration superimposed onto wide-pulse width (1000 μs) knee extensor electrical stimulation (NMES, 30 Hz) on peak muscle force, total impulse before "muscle fatigue", and the post-exercise recovery of muscle function.

METHODS

Tendon vibration (Vib), NMES (STIM) or NMES superimposed onto vibration (STIM + Vib) were applied in separate sessions to 16 healthy adults. Total torque-time integral (TTI), maximal voluntary contraction torque (MVIC) and indirect measures of muscle damage were tested before, immediately after, 1 h and 48 h after each stimulus.

RESULTS

TTI increased (145.0 ± 127.7%) in STIM only for "positive responders" to the tendon vibration (8/16 subjects), but decreased in "negative responders" (-43.5 ± 25.7%). MVIC (-8.7%) and rectus femoris electromyography (RF EMG) (-16.7%) decreased after STIM (group effect) for at least 1 h, but not after STIM + Vib. No changes were detected in indirect markers of muscle damage in any condition.

CONCLUSIONS

Tendon vibration superimposed onto wide-pulse width NMES increased TTI only in 8 of 16 subjects, but reduced voluntary force loss (fatigue) ubiquitously. Negative responders to tendon vibration may derive greater benefit from wide-pulse width NMES alone.

Gait-like vibration training improves gait abilities: a case report of a 62-year-old person with a chronic incomplete spinal cord injury

The purpose of this single-subject case study was to quantify the effect of gait-like vibration training on gait abilities after an incomplete spinal cord injury (SCI). A 62-year-old male with a chronic American Spinal Injury Association Impairment Scale D SCI at T11 completed nine sessions of gait-like vibration training in a standing position. Self-selected gait speed and distance covered within 6 min were determined before and after training to evaluate the impact of training on gait performance. Associated changes in gait kinematics were assessed with a three-dimensional motion analysis system. Results showed an improvement of gait speed (0.26 vs 0.35 m s^-1) and distance (23 vs 37 m) after nine gait-like vibration training sessions (+34.6%; +60.9%). In addition, more bilateral hip extension and larger left hip range of motion improved hip-knee cyclograms. Gait-like vibration training improved gait abilities in a person with chronic incomplete SCI.

Vibration-induced motor responses of infants with and without myelomeningocele

BACKGROUND

The severity of myelomeningocele (MMC) stems both from a loss of neurons due to neural tube defect and a loss of function in viable neurons due to reduced movement experience during the first year after birth. In young infants with MMC, the challenge is to reinforce excitability and voluntary control of all available neurons. Muscle vibration paired with voluntary movement may increase motoneuron excitability and contribute to improvements in neural organization, responsiveness, and control.

OBJECTIVES

This study examined whether infants with or without MMC respond to vibration by altering their step or stance behavior when supported upright on a treadmill.

DESIGN

This was a cross-sectional study.

METHODS

Twenty-four 2- to 10-month-old infants, 12 with typical development (TD) and 12 with MMC (lumbar and sacral lesions), were tested. Infants were supported upright with their feet in contact with a stationary or moving treadmill during 30-second trials. Rhythmic alternating vibrations were applied to the right and left rectus femoris muscles, the lateral gastrocnemius muscle, or the sole of the foot. Two cameras and behavior coding were used to determine step count, step type, and motor response to vibration onset.

RESULTS

Step count decreased and swing duration increased in infants with TD during vibration of the sole of the foot on a moving treadmill (FT-M trials). Across all groups the percentage of single steps increased during vibration of the lateral gastrocnemius muscle on a moving treadmill. Infants with MMC and younger infants with TD responded to onset of vibration with leg straightening during rectus femoris muscle stimulation and by stepping during FT-M trials more often than older infants with TD.

CONCLUSIONS

Vibration seems a viable option for increasing motor responsiveness in infants with MMC. Follow-up studies are needed to identify optimal methods of administering vibration to maximize step and stance behavior in infants.

Gravitational force modulates muscle activity during mechanical oscillation of the tibia in humans

Mechanical oscillation (vibration) is an osteogenic stimulus for bone in animal models and may hold promise as an anti-osteoporosis measure in humans with spinal cord injury (SCI). However, the level of reflex induced muscle contractions associated with various loads (g force) during limb segment oscillation is uncertain. The purpose of this study was to determine whether certain gravitational loads (g forces) at a fixed oscillation frequency (30 Hz) increases muscle reflex activity in individuals with and without SCI. Nine healthy subjects and two individuals with SCI sat with their hip and knee joints at 90° and the foot secured on an oscillation platform. Vertical mechanical oscillations were introduced at 0.3, 0.6, 1.2, 3 and 5 g force for 20 s at 30 Hz. Non-SCI subjects received the oscillation with and without a 5% MVC background contraction. Peak soleus and tibialis anterior (TA) EMG were normalized to M-max. Soleus and TA EMG were <2.5% of M-max in both SCI and non-SCI subjects. The greatest EMG occurred at the highest acceleration (5 g). Low magnitude mechanical oscillation, shown to enhance bone anabolism in animal models, did not elicit high levels of reflex muscle activity in individuals with and without SCI. These findings support the g force modulated background muscle activity during fixed frequency vibration. The magnitude of muscle activity was low and likely does not influence the load during fixed frequency oscillation of the tibia.

Effects of whole-body vibration on blood flow and neuromuscular activity in spinal cord injury

STUDY DESIGN

Crossover trial.

OBJECTIVES

To investigate the effects of whole-body vibration (WBV) on muscular activity and blood flow velocity after different vibration treatments in patients with spinal cord injury (SCI).

SETTING

Research Center on Physical Disability (Spain).

METHODS

Eight individuals with SCI received six 3-min WBV treatments depending on a combination of frequency (10, 20 or 30 Hz) and protocol (constant, that is, three consecutive minutes of WBV, or fragmented, that is, three sets of 1 min of WBV with 1 min of rest between the sets). Femoral artery blood flow velocity was registered at minutes 1, 2 and 3 of WBV, and at minutes 1 and 2 after the end of the stimulus. Electromyography activity (EMG) of vastus lateralis (VL) and vastus medialis (VM) was registered at baseline and during WBV.

RESULTS

Peak blood velocity (PBV) increased after 1, 2 and 3 min of WBV. The 10 Hz frequency did not alter blood flow, whereas the 20 Hz frequency increased PBV after 2 and 3 min of WBV, and the 30 Hz frequency increased PBV after 1, 2 and 3 min of WBV and during the first minute after the end of the stimulus. No protocol effect was observed for blood parameters. EMG activity of VL and VM increased independently of the applied frequency or protocol.

CONCLUSION

WBV is an effective method to increase leg blood flow and to activate muscle mass in SCI patients, and could be considered to be incorporated in their rehabilitation programs.

Nutritional recommendations for the management of sarcopenia

The Society for Sarcopenia, Cachexia, and Wasting Disease convened an expert panel to develop nutritional recommendations for prevention and management of sarcopenia. Exercise (both resistance and aerobic) in combination with adequate protein and energy intake is the key component of the prevention and management of sarcopenia. Adequate protein supplementation alone only slows loss of muscle mass. Adequate protein intake (leucine-enriched balanced amino acids and possibly creatine) may enhance muscle strength. Low 25(OH) vitamin D levels require vitamin D replacement.

Segmental Muscle Vibration Improves Walking in Chronic Stroke Patients With Foot Drop: A Randomized Controlled Trial

Background. Studies have described the effects of segmental muscle vibration (SMV) on brain plasticity and corticomotor excitability. Information on the treatment-induced effects of SMV in stroke patients is, however, still limited. Objectives. To assess whether the application of SMV to ankle dorsiflexor muscles of chronic stroke patients can improve walking. Methods. Forty-four patients were randomly assigned to either an experimental group (EG) or a control group (CG) and underwent 12 sessions over 4 weeks of general physical therapy. Patients in the EG also received SMV at 120 Hz over the peroneus longus and tibialis anterior for 30 minutes at the end of each session. All the participants underwent pretreatment and posttreatment gait analysis assessments. Time—distance, kinematic, and surface electromyography (EMG) data were used as outcome measures. Results. A moderate improvement in mean gait speed, normal-side swing velocity, bilateral stride length, and normal-side toe-off percentage was observed only in the EG. A significant increase in bilateral ankle dorsiflexion angle at heel contact was associated with increased maximum ankle dorsiflexion and plantarflexion degrees during the swing phase on the paretic side after treatment in EG. Surface EMG during the swing phase revealed a significant increase in the activation of the tibialis anterior muscle on the paretic side in the posttreatment assessment in the EG. Conclusions. SMV added to general physical therapy may improve gait performance in patients with foot drop secondary to chronic stroke. The authors hypothesize that this may be due to the mechanical vibration stimulation, probably as a consequence of effective brain reorganization.