Muscle activity and vibration transmissibility during whole‐body vibration in chronic stroke

Effects of transcranial electrical stimulation of the right posterior parietal cortex on physical control responses

The posterior parietal cortex plays an important role in postural stability by adapting to changes in input from the visual, vestibular, and proprioceptive systems. However, little is known regarding whether transcranial electrical stimulation of the posterior parietal cortex affects reactive postural responses. This study aimed to investigate changes in physical control responses to anodal and cathodal transcranial direct current stimulation and transcranial random noise stimulation of the right posterior parietal cortex using a simultaneous inertial measurement unit. The joint movements of the lower limb of 33 healthy volunteers were measured while standing on a soft-foam surface with eyes closed during various stimulation modalities. These modalities included anodal, cathodal transcranial direct current stimulation, and sham stimulation in Experiment 1, and transcranial random noise and sham stimulations in Experiment 2. The results showed that cathodal stimulation significantly decreased the joint angular velocity in the hip rotation, ankle inversion-eversion, and abduction-adduction directions compared to anodal or sham stimulation in Experiment 1. In contrast, there were no significant differences in physical control responses with transcranial random noise stimulation coeducation in Experiment 2. These findings suggest that transcranial electrical stimulation of the right posterior parietal cortex may modulate physical control responses; however, the effect depends on the stimulus modality.

Effectiveness of Proprioceptive Body Vibration Rehabilitation on Motor Function and Activities of Daily Living in Stroke Patients with Impaired Sensory Function

Stroke patients experience impaired sensory and motor functions, which impact their activities of daily living (ADL). The current study was designed to determine the best neurorehabilitation method to improve clinical outcomes, including the trunk-impairment scale (TIS), Berg balance scale (BBS), Fugl-Meyer assessment (FMA), and modified Barthel index (MBI), in stroke patients with impaired sensory function. Forty-four stroke survivors consistently underwent proprioceptive body vibration rehabilitation training (PBVT) or conventional physical therapy (CPT) for 30 min/session, 5 days a week for 8 weeks. Four clinical outcome variables-the FMA, TIS, BBS, and MBI-were examined pre- and post-intervention. We observed significant differences in the FMA, BBS, and MBI scores between the PBVT and CPT groups. PBVT and CPT showed significant improvements in FMA, BBS, TIS, and MBI scores. However, PVBT elicited more favorable results than CPT in patients with stroke and impaired sensory function. Collectively, this study provides the first clinical evidence of optimal neurorehabilitation in stroke patients with impaired sensory function.

Effects of whole-body vibration training in static and dynamic semi-squat patterns on the lower limb muscle activity

The decline in physical function and the deterioration of the neuromusculoskeletal system in older people can easily lead to reduced muscle strength and slower mobility in the joints of the lower limbs, increasing the incidence of chronic diseases such as muscle wasting disorders, osteoporosis, debilitation and fall and fracture. It may also affect the quality of life and functional independence of older people, and in serious cases, even directly threaten their health. This study was conducted to determine the differences in lower limb muscle activation characteristics between static semi-squat (SSS) and dynamic semi-squat (DSS) training in middle-aged and old women at different frequencies and amplitudes and to explore a personalized whole-body vibration (WBV) training instruction program suitable for them. Fifteen healthy middle-aged and old women (60.8 ± 4.18 years old) were recruited for SSS and DSS WBV training. Their muscle activity of the rectus femoris (RF), vastus medialis (VM), vastus lateralis (VL), biceps femoris (BF) and gastrocnemius (GS) were calculated using the BTS FreeEMG300 wireless surface electromyography (EMG), which participants were completed that the two different contraction patterns of squats on WBV training. The knee flexion was maintained at 45° while the subjects were performing the SSS training, while during the DSS training, the knee flexion fluctuates between 10° and 45°. The SSS exercise requires the subject to remain stationary in the squatting position and the DSS to be performed at a rhythm of 4 s/repetition, with 2 s of squatting, 1 s of standing up, and 1 s intervals. The vibration frequencies and amplitudes were changed to the WBV training intensity, and the vibration frequencies were set to 0 Hz, 30 Hz and 40 Hz, and the amplitudes were set to 0 mm, 2 mm and 4 mm. Each subject is randomised to participate in WBV training with 5 combinations of frequency and amplitude in both static and dynamic semi-squat patterns. These were 0 Hz 0 mm, 30 Hz 2 mm, 30 Hz 4 mm, 40 Hz 2 mm, 40 Hz 4 mm for the static and dynamic demi-squat patterns of WBV training. A two-way repeated measures ANOVA was applied to compare the changes in surface EMG of the lower limb muscles in different modes of SSS and DSS with WBV training. (1) Our results showed significantly interaction effects in the frequency × amplitude of root mean square (EMGrms) in GS (P < 0.05), while no significant differences were observed in the interaction effects of SSS/DSS patterns, frequencies and amplitude of RF, VM, VL and BF (P > 0.05). (2) Comparisons between groups showed that the EMGrms of the RF were significantly higher for the DSS than the SSS (P < 0.05). Additionally, the EMGrms of VL and BF at 30 Hz and 40 Hz were greater than 0 Hz (P < 0.05). Also, The EMGrms at 4 mm for the VM, VL and BF were significantly higher than 0 mm, the EMGrms at 4 mm for the VM and VL were significantly higher than 2 mm (P < 0.05), and the EMGrms at 2 mm of VL and BF were significantly higher than 0 mm (P < 0.05). (3) The results showed that WBV stimulation significantly increased the EMGrms of the GS in the SSS compared with the vibration free semi-squat alone (P < 0.05). However, there were no significant differences between WBV training protocols for SSS patterns with different frequencies and amplitudes (frequencies and amplitudes not were 0 Hz and 0 mm) (P > 0.05). Comparison of EMGrms for WBV training of the GS in DSS patterns showed that 40 Hz/4 mm was significantly higher than 0 Hz/0 mm (P < 0.05), but there was no significant difference between the remaining vibration conditions (P > 0.05). WBV training for DSS can significantly improve the activation of the RF compared to SSS pattern. Compared with no vibration, WBV could significantly improv the activity of the lower limb muscles. Additionally, an increase in amplitude from 2 to 4 mm could significantly improve VM and VL activation, while no significant improvement on lower limb muscle activation was observed for increasing vibration frequency from 30 to 40 Hz.

Effects of whole body vibration on functional capacity and respiratory functions in individuals with stroke: A randomized controlled study

BACKGROUND

Management of respiratory-related functional problems using sensory rehabilitation strategies has been poorly researched in patients with stroke.

OBJECTIVE

This study aimed to investigate whether whole body vibration (WBV) training has an effect on functional capacity and respiratory functions in patients with stroke.

METHODS

In the randomized-controlled study, 28 participants were randomized into two groups: one receiving neurodevelopmental treatment (NDT; n = 13) and one receiving both NDT and WBV (NDT + WBV; n = 15). The primary outcome measures were 6-minute walking test (6MWT) and pulmonary function test which evaluate functional and respiratory capacity. Secondary outcome included the chest circumference measurement to evaluate the thoracic expansion ability.

RESULTS

Both groups showed positive significant changes in walking distance and maximum oxygen consumption volume (VO2max), inspiratory capacity, vital capacity and chest circumference measurement scores (p <  0.05). While the NDT +WBV group showed a significantly greater increase in walking distance and VO2max levels than the NDT group (p <  0.05), there were no significant group differences in respiratory function flow and volume parameters, and chest circumference measurement.

CONCLUSION

The addition of WBV training to the treatment program has some incremental benefits on increasing functional capacity and thoracic expansion, and rehabilitating respiratory dysfunction.

Effects of passive interpersonal light touch during walking on postural control responses: An exploratory study

The effects of passive interpersonal light touch (PILT) on postural stability can be observed through improved postural coordination through haptic feedback from the contact provider to the contact receiver while walking. It is unclear, however, whether PILT affects the contact receiver's detailed physical responses, such as muscle activity, body sway, and joint movements. In this study, surface electromyography and an inertial measurement unit were used simultaneously to explore changes in walking speed and control responses induced by PILT. We evaluated fourteen healthy participants for their walking speed and physical responses under two walking conditions: no-touch (NT) and PILT. As a physical response during walking, we measured muscle activity (rectus femoris, semitendinosus, tibialis anterior, and soleus muscles), body sway (pelvis and neck), and joint angles (direction of hip, knee, and ankle joint movements). In PILT condition, fingertip contact force was measured while the contact provider touched the third level of the recipient's lumbar spine. In comparison with the NT condition, PILT condition increased walking speed and decreased body sway on neck position. There were significant correlations between walking speed and neck sway regarding NT and PILT change values. Passive haptic information to the contact receiver may assist in the smooth shift of the center of gravity position during gait through interpersonal postural coordination. These findings suggest that PILT may provide an efficient and stable gait.

Analysis of Vibration Frequency and Direction for Facilitating Upper-Limb Muscle Activity

We aimed to determine the effect of vibration frequency and direction on upper-limb muscle activation using a handheld vibrator. We recruited 19 healthy participants who were instructed to hold a handheld vibrator in their dominant hand and maintain the elbow at 90° flexion, while vertical and horizontal vibrations were applied with frequencies of 15, 30, 45, and 60 Hz for 60 s each. Surface electromyography (EMG) measured the activities of the flexor digitorum superficialis (FDS), flexor carpi radialis (FCR), extensor carpi ulnaris (ECU), extensor carpi radialis (ECR), biceps, triceps, and deltoid anterior muscles. EMG changes were evaluated as the difference in muscle activity between vibration and no-vibration (0 Hz) conditions. Muscle activity was induced under vibration conditions in both vertical and horizontal (p < 0.05) directions. At 45 Hz, FDS and FCR activities increased during horizontal vibrations, compared with those during vertical vibrations. ECU activity significantly increased under 15-Hz vertical vibrations compared with that during horizontal vibrations. Vibrations from the handheld vibrator significantly induced upper-limb muscle activity. The maximum muscle activations for FDS, ECR, ECU, biceps, and triceps were induced by 45-Hz horizontal vibration. The 60-Hz vertical and 30-Hz horizontal vibrations facilitated maximum muscle activations for the FCR and deltoid anterior, respectively.

Effects of Noisy Galvanic Vestibular Stimulation on the Muscle Activity and Joint Movements in Different Standing Postures Conditions

Objective

Noisy galvanic vestibular stimulation (nGVS) is an effective method for stabilizing posture; however, little is known regarding the detailed muscle activity and joint movement in the standing posture. This study aimed to clarify the changes in the lower limb muscle activity and joint angular velocity by nGVS intervention using the simultaneous assessment method of inertial measurement units and surface electromyography (EMG).

Methods

Seventeen healthy participants were assessed for their physical responses under four conditions (standing on a firm surface with eyes-open/eyes-closed, and a foam surface with eyes-open/eyes-closed) without stimulation (baseline) and with stimulation (sham or nGVS). Noise stimuli were applied for 30 s at a level below the perceptual threshold. The body control response was evaluated using EMG activity and angular velocity of the lower limbs.

Result

Regarding the change from baseline for each parameter, there was a significant interactive effect of EMG activity in the muscle type × intervention and EMG activity and angular velocity in the condition × intervention. Post hoc analysis revealed that the angular velocity was significantly decreased in the abduction-adduction direction in the standing on a foam surface with eyes-closed condition compared to that with eyes-open in the nGVS intervention.

Conclusion

Our results suggest that nGVS altered physical responses in different standing postural conditions. The present study is exploratory and therefore the evidence should be investigated in future studies specifically target those muscle activities and joint motion parameters.

Local vibration therapy promotes the recovery of nerve function in rats with sciatic nerve injury

OBJECTIVE

It has been reported that local vibration therapy can benefit recovery after peripheral nerve injury, but the optimized parameters and effective mechanism were unclear. In the present study, we investigated the effect of local vibration therapy of different amplitudes on the recovery of nerve function in rats with sciatic nerve injury (SNI).

METHODS

Adult male Sprague-Dawley rats were subjected to SNI and then randomly divided into 5 groups: sham group, SNI group, SNI + A-1 mm group, SNI + A-2 mm group, and SNI + A-4 mm group (A refers to the amplitude; n = 10 per group). Starting on the 7th day after model initiation, local vibration therapy was given for 21 consecutive days with a frequency of 10 Hz and an amplitude of 1, 2 or 4 mm for 5 min. The sciatic function index (SFI) was assessed before surgery and on the 7th, 14th, 21st and 28th days after surgery. Tissues were harvested on the 28th day after surgery for morphological, immunofluorescence and Western blot analysis.

RESULTS

Compared with the SNI group, on the 28th day after surgery, the SFIs of the treatment groups were increased; the difference in the SNI + A-2 mm group was the most obvious (95% confidence interval [CI]: [5.86, 27.09], P < 0.001), and the cross-sectional areas of myocytes in all of the treatment groups were improved. The G-ratios in the SNI + A-1 mm group and SNI + A-2 mm group were reduced significantly (95% CI: [-0.12, -0.02], P = 0.007; 95% CI: [-0.15, -0.06], P < 0.001). In addition, the expressions of S100 and nerve growth factor proteins in the treatment groups were increased; the phosphorylation expressions of ERK1/2 protein in the SNI + A-2 mm group and SNI + A-4 mm group were upregulated (95% CI: [0.03, 0.96], P = 0.038; 95% CI: [0.01, 0.94], P = 0.047, respectively), and the phosphorylation expression of Akt in the SNI + A-1 mm group was upregulated (95% CI: [0.11, 2.07], P = 0.031).

CONCLUSION

Local vibration therapy, especially with medium amplitude, was able to promote the recovery of nerve function in rats with SNI; this result was linked to the proliferation of Schwann cells and the activation of the ERK1/2 and Akt signaling pathways.

Characterisation of the transient mechanical response and the electromyographical activation of lower leg muscles in whole body vibration training

The aim of this study is to characterise the transient mechanical response and the neuromuscular activation of lower limb muscles in subjects undergoing Whole Body Vibration (WBV) at different frequencies while holding two static postures, with focus on muscles involved in shaping postural responses. Twenty-five participants underwent WBV at 15, 20, 25 and 30 Hz while in hack squat or on fore feet. Surface electromyography and soft tissue accelerations were collected from Gastrocnemius Lateralis (GL), Soleus (SOL) and Tibialis Anterior (TA) muscles. Estimated displacement at muscle bellies revealed a pattern never highlighted before that differed across frequencies and postures (p < 0.001). After stimulation starts, muscle oscillation peaks, drops and further stabilises, suggesting the occurrence of a neuromuscular activation to reduce the vibration-induced oscillation. The oscillation attenuation at the SOL muscle correlated with its increased activation (rho = 0.29, p < 0.001). Furthermore, only specific WBV settings led to a significant increase in muscle contraction: WBV-induced activation of SOL and GL was maximal in fore-feet (p < 0.05) and in response to higher frequencies (30 Hz vs 15 Hz, p < 0.001). The analysis of the mechanical dynamics of lower leg muscles highlights a resonant response to WBVs, that for the SOL correlates to the increased muscle activation. Despite differing across frequencies and postures, this resonant behaviour seems to discourage the use of dynamic exercises on vibrating platforms. As for the most efficient WBV combination, calf muscle response to WBVs is maximised if those muscles are already pre-contracted and the stimulation frequencies are in the 25–30 Hz range.

The Effect of Whole-Body Vibration on Proprioception and Motor Function for Individuals with Moderate Parkinson Disease: A Single-Blind Randomized Controlled Trial

Introduction

Previous studies have shown that whole-body vibration (WBV) may have a potential impact on gait and balance in individuals with Parkinson's disease (PD). However, this body of work has proven inconclusive due to the diverse disease progression and broad age range associated with PD. The effects of WBV on proprioception, a sense frequently affected by PD, has rarely been studied.

Objective

To investigate the short-term effect of WBV on proprioception and motor function for individual with moderate PD.

Design

A single-blind randomized controlled trial. Setting. A hospital and a laboratory. Participants. 32 participants with moderate PD were recruited and randomly assigned into either the WBV or conventional therapy groups. Interventions. For the WBV group, each treatment session included five, one-minute bouts of whole-body vibration paired with one-minute rest (frequency: 6 Hz; amplitude: 3 mm). Each conventional therapy participant received balance and mobility training for 10 minutes. Main Outcome Measures. Outcome measures included proprioceptive sensitivity of the upper limb, position sense of the knee joint, Unified Parkinson's disease rating scale : motor section (UPDRS-motor), functional reach test (FRT), and the timed up and go test (TUG).

Results

No statistically significant difference was found between groups. However, both groups showed a significant improvement in motor function after treatment, including UPDRS-motor (P = 0.04), less affected side of FRT (P = 0.019), and TUG (P = 0.006).

Conclusions

Although the effect of WBV was not superior to the conventional therapy, it provided a passive and safe clinical intervention as an alternative treatment, especially for individuals with motor impairment or poor balance function.

Reporting Guidelines for Whole-Body Vibration Studies in Humans, Animals and Cell Cultures: A Consensus Statement from an International Group of Experts

Simple Summary

Whole-body vibration (WBV) is an exercise or treatment method used in sports, physiotherapy, and rehabilitation. During WBV, people sit, stand, or exercise on a platform that generates vibrations. These vibrations generally occur between 20 and 60 times per second and have a magnitude of one or several millimeters. Research is focused on the effects of WBV on, for instance, physical and cognitive functions as well as the underlying mechanisms that may explain the effects. Research is not only done in humans but in animals and cell cultures as well. It is important to report the studies correctly, completely, and consistently. This way, researchers can interpret and compare each other’s studies, and data of different studies can be combined and analyzed together. To serve this goal, we developed new guidelines on how to report on WBV studies. The guidelines include checklists for human and animal/cell culture research, explanations, and examples of how to report. We included information about devices, vibrations, administration, general protocol, and subjects. The guidelines are WBV-specific and can be used by researchers alongside general guidelines for specific research designs.

Abstract

Whole-body vibration (WBV) is an exercise modality or treatment/prophylaxis method in which subjects (humans, animals, or cells) are exposed to mechanical vibrations through a vibrating platform or device. The vibrations are defined by their direction, frequency, magnitude, duration, and the number of daily bouts. Subjects can be exposed while performing exercises, hold postures, sitting, or lying down. Worldwide, WBV has attracted significant attention, and the number of studies is rising. To interpret, compare, and aggregate studies, the correct, complete, and consistent reporting of WBV-specific data (WBV parameters) is critical. Specific reporting guidelines aid in accomplishing this goal. There was a need to expand existing guidelines because of continuous developments in the field of WBV research, including but not limited to new outcome measures regarding brain function and cognition, modified designs of WBV platforms and attachments (e.g., mounting a chair on a platform), and comparisons of animal and cell culture studies with human studies. Based on Delphi studies among experts and using EQUATOR recommendations, we have developed extended reporting guidelines with checklists for human and animal/cell culture research, including information on devices, vibrations, administration, general protocol, and subjects. In addition, we provide explanations and examples of how to report. These new reporting guidelines are specific to WBV variables and do not target research designs in general. Researchers are encouraged to use the new WBV guidelines in addition to general design-specific guidelines.

Ischemic stroke-induced polyaxonal innervation at the neuromuscular junction is attenuated by robot-assisted mechanical therapy

Ischemic stroke is a leading cause of disability world-wide. Mounting evidence supports neuromuscular pathology following stroke, yet mechanisms of dysfunction and therapeutic action remain undefined. The objectives of our study were to investigate neuromuscular pathophysiology following ischemic stroke and to evaluate the therapeutic effect of Robot-Assisted Mechanical massage Therapy (RAMT) on neuromuscular junction (NMJ) morphology. Using an ischemic stroke model in male rats, we demonstrated longitudinal losses of muscle contractility and electrophysiological estimates of motor unit number in paretic hindlimb muscles within 21 days of stroke. Histological characterization demonstrated striking pre- and postsynaptic alterations at the NMJ. Stroke prompted enlargement of motor axon terminals, acetylcholine receptor (AChR) area, and motor endplate size. Paretic muscle AChRs were also more homogenously distributed across motor endplates, exhibiting fewer clusters and less fragmentation. Most interestingly, NMJs in paretic muscle exhibited increased frequency of polyaxonal innervation. This finding of increased polyaxonal innervation in stroke-affected skeletal muscle suggests that reduction of motor unit number following stroke may be a spurious artifact due to overlapping of motor units rather than losses. Furthermore, we tested the effects of RAMT - which we recently showed to improve motor function and protect against subacute myokine disturbance - and found significant attenuation of stroke-induced NMJ alterations. RAMT not only normalized the post-stroke presentation of polyaxonal innervation but also mitigated postsynaptic expansion. These findings confirm complex neuromuscular pathophysiology after stroke, provide mechanistic direction for ongoing research, and inform development of future therapeutic strategies. SIGNIFICANCE: Ischemic stroke is a leading contributor to chronic disability, and there is growing evidence that neuromuscular pathology may contribute to the impact of stroke on physical function. Following ischemic stroke in a rat model, there are progressive declines of motor unit number estimates and muscle contractility. These changes are paralleled by striking pre- and postsynaptic maladaptive changes at the neuromuscular junction, including polyaxonal innervation. When administered to paretic hindlimb muscle, Robot-Assisted Mechanical massage Therapy - previously shown to improve motor function and protect against subacute myokine disturbance - prevents stroke-induced neuromuscular junction alterations. These novel observations provide insight into the neuromuscular response to cerebral ischemia, identify peripheral mechanisms of functional disability, and present a therapeutic rehabilitation strategy with clinical relevance.

The effect of support surface and footwear condition on postural sway and lower limb muscle action of the older women

BACKGROUND

Diminished somatosensory function is a critical age-related change which is related to postural instability in the older population. Footwear is a cost-effective way to modulate the postural stability by altering sensorimotor inputs via mechanoreceptors on the plantar surface of the feet. Compared to insoles with indentions in the entire surface, we innovatively developed a textured insole with site-specific nodulous protrudous. This study thus aimed to investigate the immediate effect of the nodulous insole and supporting surface condition on static postural stability and lower limb muscle activation for healthy older women.

METHODS

This is a single-session study with repeated measurements. Twenty-three healthy older women stood on the firm (i.e., concrete floor) and foam surfaces with their eyes open in the three footwear conditions, namely barefoot, plain shoes and shoes with an innovative textured insole, for 30 seconds. Static postural sway and muscle activation of biceps femoris (BF), vastus lateralis (VL), tibialis anterior (TA), and lateral gastrocnemius (LG) of the dominant leg were measured during each testing condition.

RESULTS

Compared to a firm surface, standing on the foam could significantly increase the body sway and lower limb muscle activation (p<0.05). When standing on the foam, compared to barefoot, wearing footwear significantly decreased the VL and TA muscle activation and minimize the postural sway in medial-lateral and anterior-posterior direction, while the influence is larger for the shoes with nodulous insloe compared to the plain shoes. No significant differences between the footwear conditions for static stability and muscle activation were observed on firm surface condition.

CONCLUSIONS

For older women, footwear could improve the postural stability in the unstable surface, particularly the footwear with nodulous insole, with the underlying mechanism as enhancing the mechanoreceptors on the plantar surface of the feet.

Modulating Effects of Whole-body Vibration on Cortical Activity and Gait Function in Chronic Stroke Patients

Whole-body vibration exercise (WBVe) can provide proper somatosensory stimulation and improve muscle strength in stroke patients. This study investigated the effects of WBVe on gait function and cortical activity in patients with chronic stroke. Thirty stroke patients were randomly assigned to either the WBVe or the control group. The WBVe group received the vibration in a half-squat position for 5 minutes at an intensity of 20 Hz. The control group kept the same posture but did not receive the vibration. Cortical activity was investigated using functional near-infrared spectroscopy (fNIRS). Gait function was assessed by a 10-m walk test (10MWT), a timed up and go (TUG) test, a Fugl-Meyer Assessment, and a Tinetti Performance-Oriented Mobility Assessment (TPOMA). In group analysis of the fNIRS data, oxygenated hemoglobin concentration was significantly increased in the ipsilesional supplementary motor area, bilateral sensorimotor cortex, and contralesional prefrontal cortex in the WBVe group compared to the control group (p < 0.05). Functional assessment demonstrated a significant interaction between time and group for the 10MWT and TUG test, suggesting that the WBVe group demonstrated meaningful improvement after intervention (p < 0.05). These results suggested that WBVe modulated the cerebral cortical activities and resulted in improvement of gait function in chronic stroke patients.

Trial Registration

ClinicalTrials.gov Identifier: NCT03375346.

Efficacy of Controlled Whole-Body Vibration Training on Improving Fall Risk Factors in Stroke Survivors: A Meta-analysis

Background. Controlled whole-body vibration (CWBV) training has been applied to people with stroke. However, it remains inconclusive if CWBV reduces fall risk in this population. Objective. To (1) assess the immediate and retention effects of CWBV training on fall risk factors in people at postacute and chronic stages of stroke and (2) examine if CWBV dosage is correlated with the effect size (ES) for 3 fall risk factors: body balance, functional mobility, and knee strength. Methods. Twelve randomized controlled trials were included. ES was calculated as the standardized mean difference, and meta-analyses were completed using a random-effects model. Results. CWBV training may lead to improved balance and mobility immediately after training (ES = 0.27, P = .03 for balance; ES = 0.34, P = .02 for mobility) but not at the 3-month follow-up test (ES = 0.02, P = .89 for balance; ES = 0.70, P = .11 for mobility). CWBV affects knee strength capacity with mild ES (ES = 0.08 and 0.11, respectively, for immediate and retention effect; P ≥ .68 for both). Metaregression indicated that the immediate ES is strongly correlated with training dosage for balance (r = 0.649; P = .029) and mobility (r = 0.785; P = .036). Conclusions. CWBV training may benefit balance and mobility immediately, but the training effect may not persist among people with stroke. Additionally, the CWBV dosage correlates with the ES for body balance and mobility. More high-quality studies are needed to determine the retention effects of CWBV training.

Whole-body vibration modulates leg muscle reflex and blood perfusion among people with chronic stroke: a randomized controlled crossover trial

This study aimed to investigate the acute effect of whole-body vibration (WBV) on the reflex and non-reflex components of spastic hypertonia and intramuscular blood perfusion among individuals with chronic stroke. Thirty-six people with chronic stroke (age: 61.4 ± 6.9 years) participated in this randomized controlled cross-over study. Each participant underwent two testing conditions: static standing for 5 minutes with WBV (30 Hz, 1.5 mm) or no-vibration. We assessed the soleus H-reflex, shear modulus (ultrasound elastography) and vascular index (color power Doppler ultrasound) of the medial gastrocnemius (MG) muscle on either paretic or non-paretic side at baseline and every 1-min post-intervention up to 5 minutes. The results revealed a significant inhibition of the H/M ratio bilaterally for the WBV condition (absolute change on paretic side: 0.61 ± 0.35, p = 0.001; non-paretic side: 0.34 ± 0.23, p = 0.001), but not the control condition. The inhibition of H-reflex was sustained up to 4 minutes and 3 minutes on the paretic and non-paretic side, respectively. The vascular index of MG muscle was significantly increased only for the WBV condition [paretic: from 0.55 ± 0.07 to 1.08 ± 0.18 (p = 0.001); non-paretic: from 0.82 ± 0.09 to 1.01 ± 0.13 (p < 0.001)], which lasted for 3 minutes and 5 minutes, respectively. No significant change of the shear modulus in the MG muscle was observed, regardless of the testing condition. Based on our results, WBV had an acute effect on modulating spastic hypertonia dominated by hyperreflexia in people with chronic stroke and facilitating greater intramuscular blood perfusion. No acute effect on passive muscle stiffness was observed.