Immediate effects of 2 different whole-body vibration frequencies on muscle peak torque and stiffness

Acute neuromuscular responses to whole-body vibration in healthy individuals: A systematic review

Whole-body vibration (WBV) training has been employed alongside conventional exercise like resistance training to enhance skeletal muscle strength and performance. This systematic review examines the evidence regarding the effect of WBV on muscle activity, strength, and performance in healthy individuals. The Academic Search Ultimate, CINAHL, Cochrane CENTRAL, PubMed, ProQuest One Academic and SCOPUS databases were searched from 1990 to April 2023 to retrieve relevant studies. Methodological quality was assessed using the Modified Downs and Black checklist, while the level of evidence was evaluated through the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) tool. Even though the quality of the included studies was moderate to high, the level of evidence was very low owing to serious concerns with three or more GRADE domains (risk of bias, inconsistency, indirectness, imprecision, and publication bias) for each outcome of interest across studies. The review suggests that in WBV training, using moderate to high vibration frequencies (25-40 Hz) and high magnitudes (3-6 mm) can enhance muscle activation and strength in pelvis and lower limb muscles. However, findings regarding WBV effect on muscle performance measures were inconsistent. Future research with robust methodology is necessary in this area to validate and support these findings.

Effect of Whole-body Vibration frequency on muscle tensile state during graded plantar flexor isometric contractions

Background

Acute physiological and biomechanical alterations have been reported following whole-body vibration (WBV). Stiffening of muscles has only been anecdotally reported in response to WBV. Accordingly, this study investigated active plantar flexor muscle stiffness in response to a single WBV bout at four mechanical vibration frequencies.

Methods

Thirteen healthy adults (37.1 ± 14.4 years old) randomly received WBV in 4 different frequencies (6, 12, 24, and 0 Hz control) for 5 min. Shear wave speed (SWS) in longitudinal and transverse projections, architecture, and electric muscle activity were recorded in the medial gastrocnemius (MG) and soleus (SOL) muscle during graded plantar flexor contraction. Subjective rating of perceived muscle stiffness was assessed via Likert-scale.

Results

SWS of the MG at rest was enhanced in response to 5 min of 24 Hz WBV (p = 0.025), while a small reduction in SOL SWS was found during contraction (p = 0.005) in the longitudinal view. Subjective stiffness rating was increased following 12 Hz intervention. After 24 Hz WBV, pennation angle for MG was decreased (p = 0.011) during contraction. As a secondary finding, plantar flexor strength was significantly increased with each visit, which, however, did not affect the study's main outcome because of balanced sequence allocation.

Conclusion

SWS effects were solely limited to 24 Hz mechanical vibration and in the longitudinal projection. The observed effects are compatible with an interpretation by post-activation potentiation, warm-up, and force-distribution within the triceps surae muscles following 5 min WBV. The outcome may suggest SWS as a useful tool for assessing acute changes in muscle stiffness.

The Effects of Vibration Exposure on Lower-Limb Extensor Muscles' Stiffness, Elasticity, and Strength Responses in Untrained Young Individuals: A Randomized Controlled Trial

OBJECTIVES

The whole-body vibration (WBV) effects on muscle strength show inconsistent results. Moreover, there is no study about the WBV effect on stiffness, elasticity, and muscle strength. Therefore, the study aimed to examine the effect of WBV exposure with static squat posture on the stiffness, elasticity, and strength of the lower-limb extensor muscles.

MATERIAL AND METHODS

Forty healthy untrained young adults were divided into WBV and control groups. The experimental group received WBV exposure on 2 nonconsecutive days of the week, for 6 weeks. The MyotonPRO device was used for the assessment of the knee extensor and the ankle dorsiflexors' stiffness and elasticity. Isometric muscle strength was evaluated with a hand-held dynamometer. All measurements were done by the same assessor at baseline, and the following 6 weeks.

RESULTS

Significant group-by-time interactions were found for the elasticity scores of the right (d = 0.84, P = .01) and left (d = 0.77, P = .02) ankle dorsiflexors. Similar to the elasticity measurements, significant group-by-time interactions were observed in the muscle strength scores of the right (d = 0.45, P = .046) and left (d = 1.25, P < .001) ankle dorsiflexors. No significant effects were observed in any of the evaluated muscle stiffness measurements (P > .05), and there was no significant group-by-time interaction in knee-extensor muscle strength and elasticity scores (P > .05).

CONCLUSIONS

The study results indicate that if the ankle dorsiflexor strength and elasticity are desired to be increased, the 6-week WBV exposure in a static squat posture can be used in healthy individuals.

Triphasic 3D In Vitro Model of Bone-Tendon-Muscle Interfaces to Study Their Regeneration

The transition areas between different tissues, known as tissue interfaces, have limited ability to regenerate after damage, which can lead to incomplete healing. Previous studies focussed on single interfaces, most commonly bone-tendon and bone-cartilage interfaces. Herein, we develop a 3D in vitro model to study the regeneration of the bone-tendon-muscle interface. The 3D model was prepared from collagen and agarose, with different concentrations of hydroxyapatite to graduate the tissues from bones to muscles, resulting in a stiffness gradient. This graduated structure was fabricated using indirect 3D printing to provide biologically relevant surface topographies. MG-63, human dermal fibroblasts, and Sket.4U cells were found suitable cell models for bones, tendons, and muscles, respectively. The biphasic and triphasic hydrogels composing the 3D model were shown to be suitable for cell growth. Cells were co-cultured on the 3D model for over 21 days before assessing cell proliferation, metabolic activity, viability, cytotoxicity, tissue-specific markers, and matrix deposition to determine interface formations. The studies were conducted in a newly developed growth chamber that allowed cell communication while the cell culture media was compartmentalised. The 3D model promoted cell viability, tissue-specific marker expression, and new matrix deposition over 21 days, thereby showing promise for the development of new interfaces.

Effects of vibration training on motor and non-motor symptoms for patients with multiple sclerosis: A systematic review and meta-analysis

Background

Vibration therapy is one of the rehabilitation programs that may be effective in treating both motor and non-motor symptoms in Multiple Sclerosis patients. We conducted a comprehensive systematic review and meta-analysis to assess the effects of vibration therapy on motor and non-motor symptoms (functional mobility, balance, walking endurance, gait speed, fatigue, and quality of life) of this population.

Methods

A systematic search of PubMed, Embase, the Cochrane Library, Web of Science, Physiotherapy Evidence Database, Scopus, Google Search Engine, and the China National Knowledge Infrastructure (CNKI). Two reviewers independently assessed the study quality.

Results

Fourteen studies with 393 participants were finally included in the meta-analysis. The pooled results showed that vibration therapy had a significant advantage over the control intervention in improving balance function [mean difference (MD) = 2.04, 95% confidence interval (CI): 0.24-3.84, P = 0.03], and walking endurance (SMD = 0.34, 95% CI: 0.07-0.61, P = 0.01). Meanwhile, the degree of disability subgroup analysis revealed that the Expanded Disability Status Scale (EDSS) score (3.5-6) significantly improved functional mobility (MD: -1.18, 95% CI: -2.09 to 0.28, P = 0.01) and balance function (MD: 3.04, 95% CI: 0.49-5.59, P = 0.02) compared with the control group, and the EDSS (0-3.5) were more beneficial in walking endurance. The duration subgroup analysis indicated a significant difference in the effect of the duration (<4 weeks) on enhancing walking endurance (SMD: 0.46, 95% CI: 0.04-0.87, P = 0.03). However, no significant improvement was found in functional mobility, gait speed, fatigue, and quality of life.

Conclusion

Vibration therapy may improve balance function and walking endurance, and the degree of disability and duration of intervention may affect outcomes. The evidence for the effects of vibration therapy on functional mobility, gait speed, fatigue, and quality of life remains unclear. More trials with rigorous study designs and a larger sample size are necessary to provide this evidence.

Systematic Review Registration

PROSPERO, https://www.crd.york.ac.uk/prospero/#recordDetails, identifier: CRD42022326852.

Immediate Effects of Plantar Vibration on Fall Risk and Postural Stability in Stroke Patients: A Randomized Controlled Trial

BACKGROUND

Local vibration can improve balance problems of individuals with stroke when applied to the plantar region.

AIMS

This study aimed to determine the immediate effect of local vibration applied to the plantar region on fall risk and postural stability in patients with stroke.

STUDY DESIGN

Randomized controlled study.

METHODS

30 patients (23 male,7 female) with stroke were randomized to either vibration (n = 15; 58.47 ± 8.23 years) or control (n = 15; 58.27 ± 9.50 years) groups. Before and after the intervention, the patients were evaluated using a Biodex Balance System. Local vibration was applied to the plantar region of two feet in the supine position using a vibration device for a total of 15 min to the individuals in the vibration group. While the patients in the placebo group were in the supine position, the device was brought into contact and no vibration was applied to the plantar region of two feet for 15 min.

RESULTS

While significant improvements were observed in the postural stability and fall risk of the vibration group (p < 0.05), no significant change was observed in the placebo group (p > 0.05). Furthermore, significant improvements occurred in the SD values of the postural stability expressing postural oscillation in the vibration group (p < 0.05).

CONCLUSION

As a result of local vibration applied to the plantar region, immediate (within 5 min) significant improvements in postural stability and fall risk values were detected.

Application of acute whole-body vibration and lower-body exercise: effects on concentric torque in lower-limb muscles

Study aim: With contrary evidence regarding the effectiveness of acute whole-body vibration training (WBVT) on sporting performance, the current study examined WBVT’s effect on concentric torque of the quadriceps (Q) and hamstrings (H).

Material and methods: Following ethical approval, 11 male team sport players (age: 22.9 ± 3.3 yrs, height: 1.80 ± 0.07 m, mass: 82.5 ± 12.6 kg) completed three separate weekly WBVT sessions. Baseline and post – WBVT intervention measurements of Q and H concentric torque were recorded, using an isokinetic dynamometer, at each session. Isokinetic knee extension and flexion was performed at 180os−1 through 90o range of motion. For the training intervention, vibration amplitude remained at 2 mm, while frequency was set at 0Hz, 30Hz or 50 Hz; randomised so participants experienced one frequency per session. Torque data (Nm) and H and Q ratio (H: Q) were analysed using 3-way and 2-way ANOVA with repeated measures respectively, with three within subjects’ factors: frequency, muscle group and intervention.

Results: Main interaction effect (frequency x muscle group x intervention) was insignificant (P = 0.327). Significant muscle group x frequency (P = 0.029) and muscle group x intervention (P = 0.001) interactions were found. Intervention, regardless of WBVT, significantly increased concentric torque of H (P = 0.003) and significantly reduced concentric torque of Q (P = 0.031). While H: Q x frequency interaction was insignificant (P = 0.262), the intervention significantly improved H: Q (P = 0.001).

Conclusions: Team sport athletes experience a muscle-specific response in peak concentric torque to lower-body exercise. Acute WBVT does not provide additional positive or negative effects on Q or H strength.

Acute Effects of Whole-Body Vibration on the Postural Organization of Gait Initiation in Young Adults and Elderly: A Randomized Sham Intervention Study

Whole-body vibration (WBV) is a training method that exposes the entire body to mechanical oscillations while standing erect or seated on a vibrating platform. This method is nowadays commonly used by clinicians to improve specific motor outcomes in various sub-populations such as elderly and young healthy adults, either sedentary or well-trained. The present study investigated the effects of acute WBV application on the balance control mechanisms during gait initiation (GI) in young healthy adults and elderly. It was hypothesized that the balance control mechanisms at play during gait initiation may compensate each other in case one or several components are perturbed following acute WBV application, so that postural stability and/or motor performance can be maintained or even improved. It is further hypothesized that this capacity of adaptation is altered with aging. Main results showed that the effects of acute WBV application on the GI postural organization depended on the age of participants. Specifically, a positive effect was observed on dynamic stability in the young adults, while no effect was observed in the elderly. An increased stance leg stiffness was also observed in the young adults only. The positive effect of WBV on dynamic stability was ascribed to an increase in the mediolateral amplitude of "anticipatory postural adjustments" following WBV application, which did overcompensate the potentially destabilizing effect of the increased stance leg stiffness. In elderly, no such anticipatory (nor corrective) postural adaptation was required since acute WBV application did not elicit any change in the stance leg stiffness. These results suggest that WBV application may be effective in improving dynamic stability but at the condition that participants are able to develop adaptive changes in balance control mechanisms, as did the young adults. Globally, these findings are thus in agreement with the hypothesis that balance control mechanisms are interdependent within the postural system, i.e., they may compensate each other in case one component (here the leg stiffness) is perturbed.

Combined effects of whole body vibration and unstable shoes on balance measures in older adults: A randomized clinical trial

OBJECTIVE

The purpose of this study was to compare the efficacy of 4 weeks of whole body vibration training on balance in older adults who word two different types of shoes: unstable (unstable group) versus standard shoes (stable group).

DESIGN

Randomized, single-blind clinical trial.

PARTICIPANTS

Seventy eight eligible older adults were initially enrolled; 59 participants (mean age 69.7±5.3 years) completed the program.

INTERVENTION

Participants were randomized 1:1 to an intervention group that received whole body vibration with unstable shoes, and a control group that received whole body vibration with standard shoes.

OUTCOME MEASURES

The Fullerton Advanced Balance scale, preferred gait speed, maximum gait speed, and Fall Efficacy Scale were recorded at baseline, after the 4-week intervention, and 1 month after the end of the training program.

RESULTS

Both groups showed improvement in all outcome measures at 4 weeks (p < 0.01) with no significant between-group differences. In the unstable group, the gains were maintained at follow-up (p < 0.01) whereas the scores returned to baseline values in the stable group. At follow-up, significant between-group differences were found for Fullerton Advanced Balance scale (p < 0.001), preferred gait speed (p = 0.007) and maximum gait speed (p = 0.007), and all were in favor of the unstable group.

CONCLUSION

Combining whole body vibration with unstable shoes can be proposed as a beneficial method with relatively long-term effects to improve balance measures in older people.

Immediate effects of whole body vibration on patellar tendon properties and knee extension torque

PURPOSE

Reports about the immediate effects of whole body vibration (WBV) exposure upon torque production capacity are inconsistent. However, the changes in the torque-angle relationship observed by some authors after WBV may hinder the measurement of torque changes at a given angle. Acute changes in tendon mechanical properties do occur after certain types of exercise but this hypothesis has never been tested after a bout of WBV. The purpose of the present study was to investigate whether tendon compliance is altered immediately after WBV, effectively shifting the optimal angle of peak torque towards longer muscle length.

METHODS

Twenty-eight subjects were randomly assigned to either a WBV (n = 14) or a squatting control group (n = 14). Patellar tendon CSA, stiffness and Young's modulus and knee extension torque-angle relationship were measured using ultrasonography and dynamometry 1 day before and directly after the intervention. Tendon CSA was additionally measured 24 h after the intervention to check for possible delayed onset of swelling.

RESULTS

The vibration intervention had no effects on patellar tendon CSA, stiffness and Young's modulus or the torque-angle relationship. Peak torque was produced at ~70° knee angle in both groups at pre- and post-test. Additionally, the knee extension torque globally remained unaffected with the exception of a small (-6%) reduction in isometric torque at a joint angle of 60°.

CONCLUSION

The present results indicate that a single bout of vibration exposure does not substantially alter patellar tendon properties or the torque-angle relationship of knee extensors.

Comparison between whole-body vibration, light-emitting diode, and cycling warm-up on high-intensity physical performance during sprint bicycle exercise

The purpose of this study was to compare the effects of light-emitting diode (LED) irradiation and whole-body vibration (WBV) delivered either in isolation or combination (LED + WBV), warm-up (WU), and a control (C) treatment on performance during a sprint bicycle exercise. Ten cyclists performed a 30-second sprint cycle test under these conditions. The LED light was applied at 4 points bilaterally. Whole-body vibration consisted of 5 minutes of squats associated with WBV. LED + WBV consisted of WBV followed by LED therapy. Warm-up consisted of 17 minutes of moderate-intensity bicycle exercise. Control consisted of 10 minutes at rest. Blood lactate (BL) and ammonia (BA) levels and skin temperature (ST) were determined. Peak power (842 ± 117 vs. 800 ± 106 vs. 809 ± 128 W [p = 0.02 and p = 0.01]), relative power (12.1 ± 1.0 vs. 11.5 ± 0.9 vs. 11.6 ± 1.0 W·kg [p = 0.02 and p = 0.02]), and relative work (277 ± 23 vs. 263 ± 24 vs. 260 ± 23 J·kg [p = 0.02 and p = 0.003]) were higher in the WU group compared with the control and LED groups. In the LED + WBV group, peak (833 ± 115 vs. 800 ± 106 W [p = 0.02]) and relative (11.9 ± 0.9 vs. 11.5 ± 0.9 W·kg [p = 0.02]) power were higher than those in the control group, and relative work (272 ± 22 vs. 260 ± 23 J·kg [p = 0.02]) were improved compared with the LED group. There were no differences for BL, BA, and ST. The findings of this study confirmed the effectiveness of a warm-up as a preparatory activity and demonstrated that LED + WBV and WBV were as effective as WU in improving cyclist performance during a sprint bicycle exercise.

Whole body vibration training--improving balance control and muscle endurance

Exercise combined with whole body vibration (WBV) is becoming increasingly popular, although additional effects of WBV in comparison to conventional exercises are still discussed controversially in literature. Heterogeneous findings are attributed to large differences in the training designs between WBV and "control" groups in regard to training volume, load and type. In order to separate the additional effects of WBV from the overall adaptations due to the intervention, in this study, a four-week WBV training setup was compared to a matched intervention program with identical training parameters in both training settings except for the exposure to WBV. In a repeated-measures matched-subject design, 38 participants were assigned to either the WBV group (VIB) or the equivalent training group (CON). Training duration, number of sets, rest periods and task-specific instructions were matched between the groups. Balance, jump height and local static muscle endurance were assessed before and after the training period. The statistical analysis revealed significant interaction effects of group×time for balance and local static muscle endurance (p<0.05). Hence, WBV caused an additional effect on balance control (pre vs. post VIB +13%, p<0.05 and CON +6%, p = 0.33) and local static muscle endurance (pre vs. post VIB +36%, p<0.05 and CON +11%, p = 0.49). The effect on jump height remained insignificant (pre vs. post VIB +3%, p = 0.25 and CON ±0%, p = 0.82). This study provides evidence for the additional effects of WBV above conventional exercise alone. As far as balance and muscle endurance of the lower leg are concerned, a training program that includes WBV can provide supplementary benefits in young and well-trained adults compared to an equivalent program that does not include WBV.