Effect of whole body vibration frequency on neuromuscular activity in ACL-deficient and healthy males

Does the Addition of Whole-Body Vibration Training Improve Postural Stability and Lower Limb Strength During Rehabilitation Following Anterior Cruciate Ligament Reconstruction: A Systematic Review With Meta-analysis

OBJECTIVES

To investigate whether the addition of whole-body vibration therapy to standard rehabilitation improves postural stability and lower limb strength following anterior cruciate ligament (ACL) reconstruction.

DATA SOURCES

A computer-based literature search of MEDLINE, AMED, SPORTDiscus, Embase, CINAHL, CENTRAL, and Physiotherapy Evidence Database (PEDro) included studies up to October 2019.

MAIN RESULTS

Seven randomised controlled trials of moderate-to-high methodological quality involving 244 participants were included. Meta-analysis found statistically significant improvements in medial-lateral stability [standardized mean difference (SMD) = 0.50; 95% confidence interval (CI), 0.12-0.88] and overall stability (SMD = 0.60; 95% CI, 0.14-1.06) favoring whole-body vibration therapy, but effects were not significant for quadriceps strength (SMD = 0.24; 95% CI, -0.65 to 1.13), hamstring strength (SMD = 0.84; 95% CI, -0.05 to 1.72), lower limb strength (SMD = 0.76; 95% CI, -0.16 to 1.67), or anterior-posterior stability (SMD = 0.19; 95% CI, -0.39 to 0.76).

CONCLUSIONS

The addition of whole-body vibration therapy to standard postoperative rehabilitation following ACL reconstruction does not appear to significantly improve lower limb strength and anterior-posterior stability but may improve medial-lateral and overall postural stability. We found small sample sizes in all included trials, statistical heterogeneity, and methodological quality concerns, including publication bias, suggesting that larger high-quality trials are likely to be influential in this field. Registration: PROSPERO 155531.

Effects of Whole-Body Vibration Therapy on Quadriceps Function in Patients With Anterior Cruciate Ligament Reconstruction: A Systematic Review

CONTEXT

Quadriceps dysfunction is common for patients after anterior cruciate ligament reconstruction (ACLR). Whole-body vibration (WBV) could effectively treat quadriceps dysfunction.

OBJECTIVE

To summarize WBV protocols for patients with ACLR and to evaluate the effects of WBV on quadriceps function.

DATA SOURCES

PubMed, CINAHL, SportDiscus, Web of Science, Medline, and Embase were searched from inception to January 2020.

STUDY SELECTION

Randomized controlled trials recruiting patients with ACLR, using WBV as intervention, and reporting at least 1 of the following outcomes, strength, rate of torque development (RTD), and voluntary activation ratio of quadriceps, were included.

STUDY DESIGN

Systematic review.

EVIDENCE LEVEL

Level 3.

METHODS

This systematic review was reported according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Quality of evidence was determined by PEDro criteria and GRADE system. Participant characteristics, interventions, and the relevant results of the included studies were extracted and synthesized in a narrative way.

RESULTS

In total, 8 studies were included. Of these, 2 studies had serious risk of bias. Five of 8 studies implemented a series of WBV program ranging from 2 to 10 weeks in duration, while the other 3 studies implemented a single session of WBV. Eight WBV protocols were reported. The reported outcomes consisted of quadriceps strength, RTD, and central activation ratio. WBV protocols were heterogeneous. Low quality of evidence supported that exclusive conventional rehabilitation was more effective than exclusive WBV therapy in increasing quadriceps strength. Low quality of evidence supported that WBV combined with conventional rehabilitation was more beneficial in increasing quadriceps strength when compared with conventional rehabilitation alone. Very low quality of evidence supported the efficacy of a single session of WBV on quadriceps function.

CONCLUSIONS

There is no standardized WBV protocol for patients with ACLR, and the effectiveness of WBV in rehabilitation on quadriceps function remains inconclusive.

Effect of Whole-Body Vibration Training on Muscle Activation for Individuals with Knee Osteoarthritis

Whole-body vibration (WBV) training may improve the strength of lower extremity muscles in patients with knee osteoarthritis (KOA), but the inconsistency in vibration parameters leads to differences in findings. This cross-sectional study is aimed at observing the effects of different vibration frequencies and knee flexion angles on the activation of lower extremity muscles in patients with KOA. Enrolled participants received WBV training at 0, 30, and 60° knee flexion angles with vibration frequencies of 0, 5, 10, and 20 Hz. Activation rates for vastus medialis, vastus lateralis, rectus femoris, biceps femoris, and semitendinosus in different combinations were collected through surface electromyography. The effects of frequency and angle on muscle activation rate were quantified by repeated measures ANOVA. Individual and synergistic effects of frequency and angle were also analysed. Twenty-six participants with KOA were included. Muscle activation increased with the vibration frequency in 0–20 Hz range and with knee flexion angle in 0–60° range. WBV training at 20 Hz was the most effective for knee muscle activation, and static squatting at 60° was the most suitable for WBV training. Therefore, WBV training can increase the activation rate of knee flexor and extensor muscles in patients with KOA, and the most efficient combination was 20 Hz vibration frequency and 60° knee flexion. When applying WBV to patients with KOA, individual differences and rehabilitation purposes should be considered in selecting vibration parameters and knee angle to effectively increase neuromuscular activity.

Development and Preliminary Validation of a Pneumatic Focal Vibration System to the Mitigation of Post-Stroke Spasticity

Some evidence has demonstrated that focal vibration (FV) plays an important role in the mitigation of spasticity. However, the research on developing the FV system to mitigate the spasticity effectively has been seldom reported. To relieve post-stroke spasticity, a new pneumatic FV system has been proposed in this paper. An image processing approach, in which the edge of vibration actuator was identified by the Canny edge detector, was utilized to quantify this system's parameters: the frequency ranging from 44 Hz to 128 Hz and the corresponding amplitude. Taking one FV protocol with the frequency of 87 Hz and the amplitude 0.28 mm of this system as an example, a clinical experiment was carried out. In the clinical experiment, FV was applied over the muscle belly of the antagonist of spastic muscle for twelve chronic spastic stroke patients. Spasticity was quantified by the muscle compliance and area under the curve for muscle (AUC_muscle). The result has demonstrated that, in the state of flexion of spastic muscle, the AUC_muscle and muscle compliance of the spastic muscle significantly increased immediately after FV compared with before-FV, illustrating the mitigation of the spasticity. This study will not only provide a potential tool to relieve post-stroke spasticity, but also contribute to improving the sensory and motor function of patients with other neurological diseases, e.g. spinal cord injury, multiple sclerosis, Parkinson and dystonia, etc.

Time course of the effects of vibration on quadriceps function in individuals with anterior cruciate ligament reconstruction

Quadriceps dysfunction is a common, chronic complication following anterior cruciate ligament reconstruction (ACLR) that contributes to aberrant gait biomechanics and poor joint health. Vibration enhances quadriceps function in individuals with ACLR, but the duration of these effects is unknown. This study evaluated the time course of the effects of whole body vibration (WBV) and local muscle vibration (LMV) on quadriceps function. Twenty-four volunteers with ACLR completed 3 testing sessions during which quadriceps isometric peak torque, rate of torque development, and EMG amplitude were assessed prior to and immediately, 10, 20, 30, 45, and 60 min following a WBV, LMV, or control intervention. WBV and LMV (30 Hz, 2g) were applied during six one-minute bouts. WBV increased peak torque 5-11% relative to baseline and control at all post-intervention time points. LMV increased peak torque 6% relative to baseline at 10 min post-intervention and 4-6% relative to control immediately, 10 min, and 20 min post-intervention. The interventions did not influence EMG amplitudes or rate of torque development. The sustained improvements in quadriceps following vibration, especially WBV, suggest that it could be applied at the beginning of rehabilitation sessions to "prime" the central nervous system, potentially improving the efficacy of ACLR rehabilitative exercise.

Effect of whole body vibration on HIF-2α expression in SD rats with early knee osteoarthritis

INTRODUCTION

To investigate the effect of different frequencies of whole body vibration (WBV) on articular cartilage of early knee osteoarthritis (OA) rats and determine whether WBV would influence the pathway of hypoxia-inducible factor-2α (HIF-2α) regulation-related genes after 8 weeks of treatment.

MATERIALS AND METHODS

Forty 8-week-old OA rats were divided into five groups: sham control (SC); high frequency 60 Hz (HV₁); high frequency 40 Hz (HV₂); middle frequency 20 Hz (MV) and low frequency 10 Hz (LV). WBV (0.3 g) treatment was given 40 min/day and 5 days/week. After 8 weeks, rats were killed and knees were harvested. OA grading score: Osteoarthritis Research Society International (OARSI), and the expression of related genes: interleukin-1β (IL-1β), HIF-2α, matrix metalloproteinases-13 (MMP-13), and collagen type II alpha 1 (COL2A1), at both mRNA and protein levels were analyzed.

RESULTS

After 8 weeks of WBV, our data showed that lower frequency (10 Hz) was more effective than the higher ones, yet they all suggested that WBV alleviates the erosion of knee articular cartilage in early OA. The expression of IL-1β, HIF-2α and MMP-13 decreased with frequency and reached the lowest level at 10 Hz, the expression of COL2A1 increased with frequency and reached the highest level at 10 Hz.

CONCLUSIONS

This study demonstrates that WBV could alleviate the degeneration of knee joints in an early OA rat model. WBV regulates related gene expression at both mRNA and protein levels. HIF-2α could be a therapeutic target. The effect of WBV is frequency dependent; the lower frequency shows better effects.

Effects of vibratory stimulation on balance and gait in Parkinson's disease: a systematic review and meta-analysis

INTRODUCTION

Among the different rehabilitative approaches to Parkinson's disease, there is conflicting evidence about the effects of vibratory stimulation and its capability to modulate the central elaboration of proprioceptive stimuli. The hypothesis is that the vibration-induced sensorial perturbation (through whole body vibration [WBV] or localized vibration) can influence the motor response in complex tasks such as postural control and gait. Thus, the objective of this review was to evaluate the effect of different modalities of vibratory stimulation treatment on balance, gait signs and symptoms, and quality of life, in patients with Parkinson's disease.

EVIDENCE ACQUISITION

From the initial 1249 records, 10 of them which compared Whole Body Vibration (WBV) or localized vibration to conventional physiotherapy were included (i.e. randomized controlled trials, crossover trials, and quasi-experimental trials). Finally, five papers on WBV were included in quantitative synthesis (meta-analysis), while for three studies on localized vibrations a qualitative synthesis was performed. Two independent reviewers selected potentially relevant studies based on the inclusion criteria, extracted data, and evaluated the methodological quality.

EVIDENCE SYNTHESIS

Meta-analysis was performed among five studies on WBV treatment, whose effect was found to be significantly better than standard treatment for improving gait (measured by Timed Up and Go test and Stand-walk-sit test: standardized mean difference = -0.51; 95% CI=-1.00 to -0.01). Conversely, WBV was not significantly better than standard treatment for all the other outcomes. Due to high heterogeneity it was not possible to conduct a quantitative meta-analysis on studies of localized vibration.

CONCLUSIONS

Results of the review show that WBV can improve gait performance in patients with Parkinson's disease.

Whole body vibration of different frequencies inhibits H-reflex but does not affect voluntary activation

This study aimed to investigate the effects of whole-body vibration (WBV) at a frequency spectrum from 20 to 50 Hz on the Hoffmann (H) reflex and the voluntary motor output of ankle plantar-flexor muscles. A single-group (n: 8), repeated measures design was adopted with four conditions: standing (no vibration), 20, 35 and 50 Hz, each lasting one minute. H-reflex of the soleus muscle, maximal voluntary contraction (MVC) and central activation ratio (CAR) of the plantar-flexors were evaluated before, 1 and 5 min after each frequency condition. H-reflex decreased by 36.7% at 20 Hz, by 28% at 35 Hz, and by 34.8% at 50 Hz after one minute from WBV compared to baseline. Neither MVC nor CAR changed after WBV at all frequency conditions. The short-term, acute inhibition of the H-reflex after WBV at 20, 35 and 50 Hz suggested that decreased excitability of spinal motoneurons is not frequency dependent. On the other hand, the lack of vibration induced effects on MVC and CAR indicated that a 1-min WBV stimulus is not sufficient to affect the voluntary motor output.

Chenopodium ambrosioides associated with whole body vibration exercises alters the feed intake in Wistar rats

The consequences of treatment involving the use of a natural product and whole body vibration (WBV) exercise have been investigated. The aim of the present study was to evaluate the effects of the joint treatment with an aqueous extract of Chenopodium ambrosioides and WBV on physiological parameters in rats. Wistar rats (n=20) were divided equally into four groups: control group (CG), treated with C. ambrosioides (CHE) group, exposed to 50 Hz of mechanial vibration (VBR), and treated with C. ambrosioides and exposed to 50 Hz of mechanical vibration (VBR + CHE) daily for 6 weeks. The body mass of the animals was determined weekly, the feed intake and the stool consistency were measured daily. One day after the 6 weeks of treatment, samples of blood were collected and used for biochemical analysis. Along 6 weeks, there was an increase (P<0.001) in the feed intake in VBR group and a decrease in the CHE group in comparison with other groups. The levels of the enzyme aspartate aminotransferase (AST) in VBR + CHE group decreased (P<0.05) in comparison with other groups. No differences were found in body mass and stool consistency. WBV altered the feed intake without directly affecting the body mass. Moreover, WBV in association with C. ambrosioides caused alteration in the enzymatic activity of AST.

The Isokinetic and Electromyographic Assessment of Knee Muscles Strength in the Short- and Long-Term Type 2 Diabetes

BACKGROUND

Type 2 diabetes (T2DM) patients are subject to muscle weakness.

OBJECTIVES

The aim of the study was an assessment of electromyographic (EMG) activity of knee muscles during isometric maximal voluntary contraction in the different disease durations of T2DM.

METHODS

Eighteen patients with less than 10 years and twelve patients with more than 10 years of T2DM were compared with nineteen matched healthy control subjects. EMG of flexor and extensor muscles of knee concurrently with isometric maximal peak torque of knee flexion and extension at 75 degrees of knee flexion were recorded in three groups.

RESULTS

Isometric maximal peak torque of extension and root mean squared (RMS) of vastus lateralis and medial hamstring in the healthy control was significantly higher than both patient groups. Whenever the maximal isometric peak flexion torque was not significantly different between groups, the mean power frequency (MPF) of flexor muscles especially medial hamstrings were higher in the short-term T2DM than healthy control groups. The two factors, gender and age, had significant effect on maximal peak torque and RMS of knee muscles.

CONCLUSIONS

EMG could show the effect of T2DM, gender and age on knee muscles activity. It seems that the medial hamstring was the most sensitive muscle of knee compartment to show the effect of T2DM and difference of short and long-term T2DM in EMG study.

Whole-Body and Local Muscle Vibration Immediately Improve Quadriceps Function in Individuals With Anterior Cruciate Ligament Reconstruction

OBJECTIVE

To determine the immediate effects of a single session of whole-body vibration (WBV) and local muscle vibration (LMV) on quadriceps function in individuals with anterior cruciate ligament reconstruction (ACLR).

DESIGN

Singe-blind, randomized crossover trial.

SETTING

Research laboratory.

PARTICIPANTS

Population-based sample of individuals with ACLR (N=20; mean age ± SD, 21.1±1.2y; mean mass ± SD, 68.3±14.9kg; mean time ± SD since ACLR, 50.7±21.3mo; 14 women; 16 patellar tendon autografts, 3 hamstring autografts, 1 allograft).

INTERVENTIONS

Participants performed isometric squats while being exposed to WBV, LMV, or no vibration (control). Interventions were delivered in a randomized order during separate visits separated by 1 week.

MAIN OUTCOME MEASURES

Quadriceps active motor threshold (AMT), motor-evoked potential (MEP) amplitude, Hoffmann reflex (H-reflex) amplitude, peak torque (PT), rate of torque development (RTD), electromyographic amplitude, and central activation ratio (CAR) were assessed before and immediately after a WBV, LMV, or control intervention.

RESULTS

There was an increase in CAR (+4.9%, P=.001) and electromyographic amplitude (+16.2%, P=.002), and a reduction in AMT (-3.1%, P<.001) after WBV, and an increase in CAR (+2.7%, P=.001) and a reduction in AMT (-2.9%, P<.001) after LMV. No effect was observed after WBV or LMV in H-reflex, RTD, or MEP amplitude. AMT (-3.7%, P<.001), CAR (+5.7%, P=.005), PT (+.31Nm/kg, P=.004), and electromyographic amplitude (P=.002) in the WBV condition differed from the control condition postapplication. AMT (-3.0% P=.002), CAR (+3.6%, P=.005), and PT (+.30Nm/kg, P=.002) in the LMV condition differed from the control condition postapplication. No differences were observed between WBV and LMV postapplication in any measurement.

CONCLUSIONS

WBV and LMV acutely improved quadriceps function and could be useful modalities for restoring quadriceps strength in individuals with knee pathologies.