Vibration as an exercise modality: how it may work, and what its potential might be. Eur J Appl Physiol. 2010;108:877-904. [PMID: 20012646 DOI: 10.1007/s00421-009-1303-3]

The effect of early whole-body vibration therapy on neuromuscular control after anterior cruciate ligament reconstruction: a randomized controlled trial

BACKGROUND

Despite rehabilitation training, deficiency in knee joint position sense, muscular performance, postural control, and functional ability is common after anterior cruciate ligament reconstruction (ACLR). Whole-body vibration therapy (WBVT), which is initiated from 3 months postoperatively, has proven benefits. However, the effect of earlier WBVT is unknown.

PURPOSE

To investigate the effect of early WBVT on neuromuscular control after ACLR.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

A total of 48 patients with unilateral complete isolated ACL tears were recruited. Single-bundle hamstring ACLR was performed in all patients. After surgery, they were randomly assigned to either the reference or treatment group. Reference group patients received conventional ACL rehabilitation, while treatment group patients received 8 weeks of WBVT in addition to conventional rehabilitation, starting from 1 month postoperatively. Joint position sense, postural control, and knee isokinetic performance were assessed before surgery and at 1, 3, and 6 months postoperatively using the Biodex dynamometer, Biodex Stability System, and Cybex NORM, respectively. Knee range of motion (ROM), stability (manual testing and KT-1000 arthrometer), and functional ability (single-legged hop test, triple hop test, shuttle run test, and carioca test) were also examined. Two-way repeated-measures analysis of variance and the Mann-Whitney U test were used for statistical analysis.

RESULTS

There was no complication throughout the rehabilitation. All patients achieved full knee ROM and stable knee joints at 6 months after surgery. The WBVT group demonstrated significantly better postural control, muscle performance, single-legged hop, and shuttle run (P < .05) than the reference group, but there was no significant difference in knee joint position sense, triple hop, carioca, ROM, and stability (P > .05).

CONCLUSION

Early WBVT started from 1 month postoperatively was an effective training method without compromising knee ROM and stability. It improved postural control, isokinetic performance, single-legged hop, and shuttle run but not knee joint position sense, triple hop, and carioca.

Plantar flexion force induced by amplitude-modulated tendon vibration and associated soleus V/F-waves as an evidence of a centrally-mediated mechanism contributing to extra torque generation in humans

Background

High-frequency trains of electrical stimulation applied over the human muscles can generate forces higher than would be expected by direct activation of motor axons, as evidenced by an unexpected relation between the stimuli and the evoked contractions, originating what has been called “extra forces”. This phenomenon has been thought to reflect nonlinear input/output neural properties such as plateau potential activation in motoneurons. However, more recent evidence has indicated that extra forces generated during electrical stimulation are mediated primarily, if not exclusively, by an intrinsic muscle property, and not from a central mechanism as previously thought. Given the inherent differences between electrical and vibratory stimuli, this study aimed to investigate: (a) whether the generation of vibration-induced muscle forces results in an unexpected relation between the stimuli and the evoked contractions (i.e. extra forces generation) and (b) whether these extra forces are accompanied by signs of a centrally-mediated mechanism or whether intrinsic muscle properties are the predominant mechanisms.

Methods

Six subjects had their Achilles tendon stimulated by 100 Hz vibratory stimuli that linearly increased in amplitude (with a peak-to-peak displacement varying from 0 to 5 mm) for 10 seconds and then linearly decreased to zero for the next 10 seconds. As a measure of motoneuron excitability taken at different times during the vibratory stimulation, short-latency compound muscle action potentials (V/F-waves) were recorded in the soleus muscle in response to supramaximal nerve stimulation.

Results

Plantar flexion torque and soleus V/F-wave amplitudes were increased in the second half of the stimulation in comparison with the first half.

Conclusion

The present findings provide evidence that vibratory stimuli may trigger a centrally-mediated mechanism that contributes to the generation of extra torques. The vibration-induced increased motoneuron excitability (leading to increased torque generation) presumably activates spinal motoneurons following the size principle, which is a desirable feature for stimulation paradigms involved in rehabilitation programs and exercise training.

Local metabolic rate during whole body vibration

Whole body vibration (WBV) platforms are currently used for muscle training and rehabilitation. However, the effectiveness of WBV training remains elusive, since scientific studies vary largely in the vibration parameters used. The origin of this issue may be related to a lack in understanding of the training intensity that is imposed on individual muscles by WBV. Therefore, this study evaluates the training intensity in terms of metabolic rate of two lower-extremity muscles during WBV under different vibration parameters. Fourteen healthy male subjects were randomly exposed to 0 (control)-, 10-, 17-, and 28-Hz vibrations while standing upright on a vibration platform. A near-infrared spectrometer was used to determine the gastrocnemius medialis (GM) and vastus lateralis (VL) muscles' metabolic rates during arterial occlusion. The metabolic rates during each vibration condition were significantly higher compared with control for both muscles (P < 0.05). Each increase in vibration frequency translated into a significantly higher metabolic rate than the previous lower frequency (P < 0.05) for both muscles. The current study showed that the local metabolic rate during WBV at 28 Hz was on average 5.4 times (GM) and 3.7 times (VL) of the control metabolic rate. The substantial changes in local metabolic rate indicate that WBV may represent a significant local training stimulus for particular leg muscles.

The influence of a 5-wk whole body vibration on electrophysiological properties of rat hindlimb spinal motoneurons

The study aimed at determining the influence of a whole body vibration (WBV) on electrophysiological properties of spinal motoneurons. The WBV training was performed on adult male Wistar rats, 5 days a week, for 5 wk, and each daily session consisted of four 30-s runs of vibration at 50 Hz. Motoneuron properties were investigated intracellularly during experiments on deeply anesthetized animals. The experimental group subjected to the WBV consisted of seven rats, and the control group of nine rats. The WBV treatment induced no significant changes in the passive membrane properties of motoneurons. However, the WBV-evoked adaptations in excitability and firing properties were observed, and they were limited to fast-type motoneurons. A significant decrease in rheobase current and a decrease in the minimum and the maximum currents required to evoke steady-state firing in motoneurons were revealed. These changes resulted in a leftward shift of the frequency-current relationship, combined with an increase in slope of this curve. The functional relevance of the described adaptive changes is the ability of fast motoneurons of rats subjected to the WBV to produce series of action potentials at higher frequencies in a response to the same intensity of activation. Previous studies proved that WBV induces changes in the contractile parameters predominantly of fast motor units (MUs). The data obtained in our experiment shed a new light to possible explanation of these results, suggesting that neuronal factors also play a substantial role in MU adaptation.

Potential beneficial effects of whole-body vibration for muscle recovery after exercise

Whole-body vibration is an emerging strategy used by athletes and exercising individuals to potentially accelerate muscle recovery. The vibration elicits involuntary muscle stretch reflex contractions leading to increased motor unit recruitment and synchronization of synergist muscles, which may lead to greater training adaptations over time. Intense exercise training, especially eccentric muscle contractions, will inevitably lead to muscle damage and delayed onset muscle soreness, which may interfere with the maintenance of a planned training program. Whole-body vibration before and after exercise shows promise for attenuating muscle soreness and may be considered as an adjunct to traditional therapies (i.e., massage, cryotherapy) to accelerate muscle recovery.

Analysis of muscle fatigue induced by isometric vibration exercise at varying frequencies

An increase in neuromuscular activity, measured by electromyography (EMG), is usually observed during vibration exercise. The underlying mechanisms are however unclear, limiting the possibilities to introduce and exploit vibration training in rehabilitation programs. In this study, a new training device is used to perform vibration exercise at varying frequency and force, therefore enabling the analysis of the relationship between vibration frequency and muscle fatigue. Fatigue is estimated by maximum voluntary contraction measurement, as well as by EMG mean-frequency and conduction-velocity analysis. Seven volunteers performed five isometric contractions of the biceps brachii with a load consisting of a baseline of 80% of their maximum voluntary contraction (MVC), with no vibration and with a superimposed 20, 30, 40, and 50 Hz vibrational force of 40 N. Myoelectric and mechanical fatigue were estimated by EMG analysis and by assessment of the MVC decay, respectively. A dedicated motion artifact canceler, making use of accelerometry, is proposed to enable accurate EMG analysis. Use of this canceler leads to better interpolation of myoelectric fatigue trends and to better correlation between mechanical and myoelectric fatigue. In general, our results suggest vibration at 30 Hz to be the most fatiguing exercise. These results contribute to the analysis of vibration exercise and motivate further research aiming at improved training protocols.

Ten-week whole-body vibration training improves body composition and muscle strength in obese women

This work explored the short-term effect of whole body vibration (WBV) training on anthropometry, body composition and muscular strength in obese women. Fifty obese women (age = 46.8 ± 7.81[SD]y; BMI = 35.1 ± 3.55 kg/m(2)) were assigned to a ten-week WBV training period, two times a week (in each session, 14 min vibration training, 5 min rest; vibration amplitude 2.0-5.0mm, frequency 40-60 Hz), with (n = 18) or without (n = 17) radiofrequency, or to a non-exercise control group (n = 15). Subjects were instructed not to change their habitual lifestyle. Before and after the ten-week experimental period, anthropometric measurements, dual-energy X-ray absorptiometry (DXA), and the leg press, leg curl and leg extension strength tests were carried out. All changes in the two groups of WBV training, with or without radiofrequency, were similar and these groups were combined in a single WBV intervention group. As compared to controls, subjects submitted to WBV training had significantly lower BMI, total body and trunk fat, sum of skinfolds and body circumferences. On the other hand, lower limb strength tests were increased in the WBV group. These preliminary results suggest that WBV training may improve body composition and muscular strength in obese women and may be a useful adjuvant to lifestyle prescriptions.

Acute bone marker responses to whole-body vibration and resistance exercise in young women

Whole-body vibration (WBV) augments the musculoskeletal effects of resistance exercise (RE). However, its acute effects on bone turnover markers (BTM) have not been determined. This study examined BTM responses to acute high-intensity RE and high-intensity RE with WBV (WBV+RE) in young women (n=10) taking oral contraceptives in a randomized, crossover repeated measures design. WBV+RE exposed subjects to 5 one-minute bouts of vibration (20 Hz, 3.38 peak-peak displacement, separated by 1 min of rest) before RE. Fasting blood samples were obtained before (Pre), immediately after WBV (PostVib), immediately after RE (IP), and 30-min after RE (P30). Bone alkaline phosphatase did not change at any time point. Tartrate-resistant acid phosphatase 5b significantly increased (p<0.05) from the Pre to PostVib, then decreased from IP to P30 for both conditions. C-terminal telopeptide of type I collagen (CTX) significantly decreased (p<0.05) from Pre to PostVib and from Pre to P30 only for WBV+RE. WBV+RE showed a greater decrease in CTX than RE (-12.6% ± 4.7% vs -1.13% ± 3.5%). In conclusion, WBV was associated with acute decreases in CTX levels not elicited with RE alone in young women.

The effects of whole-body vibration on the cross-transfer of strength

This study investigated whether the use of superimposed whole-body vibration (WBV) during cross-education strength training would optimise strength transfer compared to conventional cross-education strength training. Twenty-one healthy, dominant right leg volunteers (21 ± 3 years) were allocated to a strength training (ST, m = 3, f = 4), a strength training with WBV (ST + V, m = 3, f = 4), or a control group (no training, m = 3, f = 4). Training groups performed 9 sessions over 3 weeks, involving unilateral squats for the right leg, with or without WBV (35 Hz; 2.5 mm amplitude). All groups underwent dynamic single leg maximum strength testing (1RM) and single and paired pulse transcranial magnetic stimulation (TMS) prior to and following training. Strength increased in the trained limb for the ST (41%; ES = 1.14) and ST + V (55%; ES = 1.03) groups, which resulted in a 35% (ES = 0.99) strength transfer to the untrained left leg for the ST group and a 52% (ES = 0.97) strength transfer to the untrained leg for the ST + V group, when compared to the control group. No differences in strength transfer between training groups were observed (P = 0.15). For the untrained leg, no differences in the peak height of recruitment curves or SICI were observed between ST and ST + V groups (P = 1.00). Strength training with WBV does not appear to modulate the cross-transfer of strength to a greater magnitude when compared to conventional cross-education strength training.

Human cutaneous sensors on the sole of the foot: altered sensitivity and recovery time after whole body vibration

The goal of this study was to investigate the effect of whole body vibration (WBV) on human tactile sensitivity, both the immediate effects and the recovery time in the case of altered sensitivity. Twenty adults (25.3±2.6 years, 10 males) participated in a 10-min WBV session, at a frequency of 42 Hz with 2 mm amplitude in a spiral mode. Sensitivity was measured before and four times after WBV exposure. Pressure sensation was determined using Von Frey monofilaments. Vibration perception thresholds for 30 and 200 Hz were measured using a custom built neurothesiometer. The sensation was measured in 5 anatomical regions of the right foot. Sensitivity of measured cutaneous perception was significantly reduced. Fast-adapting mechanoreceptors for 200 Hz and 30 Hz showed 5.2 and 3.8 times lower sensation values immediately after WBV, respectively. Pressure sensation was 2 times lower in comparison to the baseline condition. In general, tactile sensitivity recovery time was between 2 and 3 h. WBV influences the discharge of fast-adapting skin mechanoreceptors. By determining the recovery time, it might be possible to estimate how long the effects of WBV on tactile sensitivity last.

Maximizing information from space data resources: a case for expanding integration across research disciplines

Regulatory systems are affected in space by exposure to weightlessness, high-energy radiation or other spaceflight-induced changes. The impact of spaceflight occurs across multiple scales and systems. Exploring such interactions and interdependencies via an integrative approach provides new opportunities for elucidating these complex responses. This paper argues the case for increased emphasis on integration, systematically archiving, and the coordination of past, present and future space and ground-based analogue experiments. We also discuss possible mechanisms for such integration across disciplines and missions. This article then introduces several discipline-specific reviews that show how such integration can be implemented. Areas explored include: adaptation of the central nervous system to space; cerebral autoregulation and weightlessness; modelling of the cardiovascular system in space exploration; human metabolic response to spaceflight; and exercise, artificial gravity, and physiologic countermeasures for spaceflight. In summary, spaceflight physiology research needs a conceptual framework that extends problem solving beyond disciplinary barriers. Administrative commitment and a high degree of cooperation among investigators are needed to further such a process. Well-designed interdisciplinary research can expand opportunities for broad interpretation of results across multiple physiological systems, which may have applications on Earth.

Vascular adaptations induced by 6 weeks WBV resistance exercise training

BACKGROUND

The impact of whole-body vibration (WBV) upon the cardiovascular system is receiving increasing attention. Despite numerous studies addressing the acute cardiovascular effects of WBV training, very little is known regarding long-term adaptations in healthy humans.

METHODS

A 6-week training study, with a 70 days follow-up was designed to compare resistive exercise with or without super-imposed whole-body vibrations. Arterial diameter, intima media thickness and flow-mediated dilation (FMD) were assessed by ultrasonography in the superficial femoral artery (SFA), the brachial (BA) and the carotid arteries (CA).

RESULTS

SFA resting diameter was increased from 6·22 mm (SD = 0·69 mm) at baseline to 6·52 mm (SD = 0·74 mm) at the end of the training period (P = 0·03) with no difference between groups (P = 0·48). Arterial wall thickness was significantly reduced by 4·3% (SD = 11%) in the CA only (P = 0·04). FMD was not affected by any of the interventions and in any of the investigated arteries.

CONCLUSION

To the best of our knowledge, this has been the first study to show that the superposition of vibration upon conventional resistance exercise does not have a specific effect upon long-term vascular adaptation in asymptomatic humans. Our findings seem to be at variance with the findings observed in a bed-rest setting. One possible explanation could be that the independently saturable effects of flow-mediated versus acceleration-related endothelial shear stresses on arterial structure and function differ between ambulatory and bed-rest conditions.

Does whole body vibration training affect knee kinematics and neuromuscular control in healthy people?

This study aimed to investigate the effect of whole body vibration (WBV) training on the knee kinematics and neuromuscular control after single-legged drop landings. Surface electromyographic (EMG) activity of the rectus femoris and hamstring muscles and knee and ankle accelerometry signals were acquired from 42 healthy volunteers. Participants performed three pre-test landings and after a recovery period of three minutes, they completed one set of six bouts of WBV each of one minute duration (30 Hz - 4 mm), followed by a single-leg drop landing. After the WBV intervention no significant changes were observed in the kinematic outcomes measured, although the time to stabilise the lower-limb was significantly lower after the vibration training (F(8,41) = 6.55; P < 0.01). EMG analysis showed no significant differences in the amplitude of rectus femoris or hamstring muscles after WBV training, however, significant differences in EMG frequency of the rectus femoris were found before (F(8,41) = 7.595; P < 0.01) and after toe-down (F(8,41) = 4.440; P < 0.001). Finally, no significant changes were observed in knee or ankle acceleration after WBV. Results suggest that WBV can help to acutely enhance knee neuromuscular control, which may have clinical significance and help in the design of rehabilitation programmes.

Influence of whole-body vibration on biodistribution of the radiopharmaceutical [99mTc]methylene diphosphonate in Wistar rats

PURPOSE

The radionuclide bone scan is the basis of skeletal nuclear medicine imaging. Bone scintigraphy is a highly sensitive method for indicating disease in bone. Mechanical stimulation in the manner of whole-body vibration (WBV) appears beneficial to the maintenance and/or enhancement of skeletal mass in individuals. The aim of this work was to evaluate the effect of WBV on the biodistribution of the radiopharmaceutical [99mTc]methylene diphosphonate (99mTc-MDP) in Wistar rats.

MATERIALS AND METHODS

In the biodistribution analysis, animals were anesthetized with sodium thiopental, the radiopharmaceutical (99m)Tc-MDP was administered via ocular plexus and after 10 min the animals were submitted to vibration of 20 Hz (1 min) in an oscillatory platform. Following, the animals were sacrificed, the organs were isolated, the radioactivity determined in a well counter, and the percentages of radioactivity per gram (%ATI/g) in the organs were calculated. An unpaired t-test following Welch test (p < 0.05) was done for statistical analysis of the results.

RESULTS

The biodistribution was significantly (p < 0.05) decreased in kidney, bone, lung, stomach, prostate and bowel.

CONCLUSION

The analysis of the results indicates that the vibration could produce metabolic alterations with influence in the uptake of the radiopharmaceutical 99mTc-MDP in bone, stomach, bowel, prostate, kidney and bladder.

Acute effect of whole-body vibration on power, one-repetition maximum, and muscle activation in power lifters

The purpose of this study was to investigate the acute effect of whole-body vibration with a frequency of 50 Hz (WBV(50Hz)) on peak power in squat jump (SJ), 1 repetition maximum (1RM) in parallel squat, and electromyography (EMG) activity and compare them with no-vibration conditions in power lifters. Twelve national level male power lifters (age 24 ± 5 years, body mass 110 ± 24 kg, height 179 ± 7 cm) tested peak power in SJ and 1RM in parallel squat while they were randomly exposed to WBV(50Hz) or to no vibration. These tests were performed in a Smith Machine. Peak power output was higher while performed with a WBV(50Hz) compared with the no-WBV condition (p < 0.05). This increase in power output was accompanied by higher EMG starting values and EMG peak values of the investigated thigh muscles during WBV(50Hz) (p < 0.05). There was no difference between adding WBV(50Hz) and no-vibration conditions in 1RM parallel squat. In conclusion, the results of this study suggest that the application of WBV(50Hz) acutely increases peak power output during SJ in well strength trained individuals such as power lifters. This increase in power was accompanied by an increased EMG activity in the quadriceps muscles. However, in 1RM parallel squat, there was no difference between WBV50Hz and no-vibration conditions. Therefore, adding WBV(50Hz) has no acute additive effect on 1RM parallel squat in power lifters and, based on the present findings, may thus not be recommended in the training to improve 1RM in power lifters. However, WBV(50Hz) seems to have an acute additive effect on peak power output and may be used in well strength trained individuals for whom a high power output is important for performance.

Hematuria in a runner after treatment with whole body vibration: a case report

The use of whole body vibration (WBV) for therapeutic purposes is far from being standardized and the training protocols reported in the literature vary considerably. Currently, the optimal threshold for a beneficial effect is undetermined, and caution regarding potential health risks due to WBV is always necessary. In this case report, we present a 34-year-old otherwise healthy elite athlete (steeplechase runner) who suffered two episodes of hematuria (HT) after WBV training. Shortly after the third WBV, he had an episode of bright red urine. Seven days later, following the next WBV session (and again before his daily running session), a reddish-colored urine reappeared. Our patient was advised to stop WBV training and to take fluid before and during exertion. He did not experience any episode of HT during a 1-year follow-up with periodic check-ups, in spite of the continuation of his sporting career. The concomitance of the two types of trauma - daily running and WBV - could have been critical in this case for producing HT. In particular, we think that platforms providing side-alternating vibration (such as the Galileo platform) may pose some health risks if the feet are positioned too far from the axis of rotation.

Benefits of whole-body vibration with an oscillating platform for people with multiple sclerosis: a systematic review

The objective of this work was to investigate the effects of whole-body vibration on people with multiple sclerosis (MS). PubMed, CINAHL and Scopus databases were systematically searched for studies on the use of whole-body vibration (WBV) exercise in people with MS. These searches were supplemented with material identified in the references and in the authors' personal files. A qualitative analysis was performed to summarize the findings. Five studies with a total of seventy-one subjects were identified. All of these studies had small numbers of subjects (3-25), and two of the studies had no control groups. Some investigations have shown significant improvements of the muscle strength, of the functional mobility, and of the timed get up and go test in patients with MS. The number of publications found in the databanks searched is small, and in general, they have limitations in the design of protocols with a weakness to the interpretation of the findings. However, the analysis of the findings in these studies permits to conclude that some papers indicate that WBV exercises could benefit patients with MS. In addition, we suggest further larger scale investigations with controlled parameters and well-designed protocols into the effects of WBV exercises in people with MS.

Effects of whole-body vibration with or without localized radiofrequency on anthropometry, body composition, and motor performance in young nonobese women

OBJECTIVES

The study investigated the effect of whole-body vibration (WBV) alone and in association with localized radiofrequency on fat deposits in young nonobese subjects.

METHODS

Forty-four (44) healthy, nonobese women aged 25.3±5.26 years, body-mass index (BMI) 21.7±2.47 kg/m(2) were randomly assigned to an 8-week trial of WBV (2 sessions per week) or WBV plus localized radiofrequency (WBV+RF) in the abdominal, buttock, and thigh region. Anthropometry, body composition (dual-energy x-ray absorptiometry, DXA), and motor performance were assessed before and after the trial. Data were analyzed by one-way analysis of variance (ANOVA) or ANOVA for repeated measures (group×time).

RESULTS

Valid data were obtained for 36 women (WBV, n=18; WBV+RF, n=18). Body mass and BMI did not change after trial. Body circumferences were unchanged or slightly reduced, with no difference between groups. Skinfold thickness was significantly reduced at several sites in the whole study population (n=36), reduction being higher at the thigh site in the WBV+RF group. According to DXA analysis, total body lean mass increased (p=0.009) and total body fat mass decreased (p=0.036) in the whole study population after trial with no significant difference between the WBV and WBV+RF group in spite of larger absolute changes in the latter. Standing long jump improved after trial with no change in flamingo balance test.

CONCLUSIONS

An 8-week WBV training is effective in inducing positive body composition changes as well as increased muscle strength in women; it could be recommended as an alternative/complementary tool in physical activity or fitness programs as it is well tolerated. The current data give limited support to the association of localized RF treatment and WBV training as synergistic in inducing body fat mass loss; such a beneficial effect should be further investigated in subject with larger subcutaneous fat deposits (i.e., overweight or obese).

Strength training with superimposed whole body vibration does not preferentially modulate cortical plasticity

Paired-pulse transcranial magnetic stimulation (TMS) was used to investigate 4 wks of leg strength training with and without whole body vibration (WBV) on corticospinal excitability and short-latency intracortical inhibition (SICI). Participants (n = 12) were randomly allocated to either a control or experimental (WBV) group. All participants completed 12 squat training sessions either with (WBV group) or without (control group) exposure to WBV (f = 35 Hz, A = 2.5 mm). There were significant (P < 0.05) increases in squat strength and corticospinal excitability and significant (P < 0.05) reductions in SICI for both groups following the 4 wk intervention. There were no differences detected between groups for any dependant variable (P > 0.05). It appears that WBV training does not augment the increase in strength or corticospinal excitability induced by strength training alone.

The influence of vibration type, frequency, body position and additional load on the neuromuscular activity during whole body vibration

This study aimed to assess the influence of different whole body vibration (WBV) determinants on the electromyographic (EMG) activity during WBV in order to identify those training conditions that cause highest neuromuscular responses and therefore provide optimal training conditions. In a randomized cross-over study, the EMG activity of six leg muscles was analyzed in 18 subjects with respect to the following determinants: (1) vibration type (side-alternating vibration (SV) vs. synchronous vibration (SyV), (2) frequency (5-10-15-20-25-30 Hz), (3) knee flexion angle (10°-30°-60°), (4) stance condition (forefoot vs. normal stance) and (5) load variation (no extra load vs. additional load equal to one-third of the body weight). The results are: (1) neuromuscular activity during SV was enhanced compared to SyV (P < 0.05); (2) a progressive increase in frequency caused a progressive increase in EMG activity (P < 0.05); (3) the EMG activity was highest for the knee extensors when the knee joint was 60° flexed (P < 0.05); (4) for the plantar flexors in the forefoot stance condition (P < 0.05); and (5) additional load caused an increase in neuromuscular activation (P < 0.05). In conclusion, large variations of the EMG activation could be observed across conditions. However, with an appropriate adjustment of specific WBV determinants, high EMG activations and therefore high activation intensities could be achieved in the selected muscles. The combination of high vibration frequencies with additional load on an SV platform led to highest EMG activities. Regarding the body position, a knee flexion of 60° and forefoot stance appear to be beneficial for the knee extensors and the plantar flexors, respectively.

Whole Body Vibration Training is Osteogenic at the Spine in College-Age Men and Women

Osteoporosis is a chronic skeletal disease characterized by low bone mass which is currently challenging the American health care system. Maximizing peak bone mass early in life is a cost-effective method for preventing osteoporosis. Whole body vibration (WBV) is a novel exercise method with the potential to increase bone mass, therefore optimizing peak bone and decreasing the risk for osteoporotic fracture. The aim of this investigation was to evaluate changes in bone mineral density at the hip, spine, and whole body in college-age men and women who underwent a WBV training protocol. Active men (n=6) and women (n=4), ages 18-22 participated in the WBV training; while an additional 14 volunteers (1 male, 13 female) served as controls. All participants completed baseline and follow-up questionnaires to assess health history, physical activity, dietary intake, and menstrual history. The WBV training program, using a Vibraflex 550, incorporated squats, stiff-leg dead lifts, stationary lunges, push-up holds, bent-over rows, and jumps performed on the platform, and occurred 3 times a week, for 12 weeks. Dual energy x-ray absorptiometry (Hologic Explorer, Waltham, MA, USA) was used to assess bone mineral density (BMD, g/cm(2)). A two-tailed, t-test identified significantly different changes in BMD between the WBV and control groups at the lateral spine (average change of 0.022 vs. -0.015 g/cm(2)). The WBV group experienced a 2.7% and 1.0% increase in BMD in the lateral spine and posterior-anterior spine while the control group decreased 1.9% and 0.9%, respectively. Results indicate that 12 weeks of WBV training was osteogenic at the spine in college-age men and women.

Low load exercises targeting the gluteal muscle group acutely enhance explosive power output in elite athletes

The purpose of this study was to investigate the acute effect of 3 warm-up protocols on peak power production during countermovement jump (CMJ) testing. The intention was to devise and compare practical protocols that could be applied as a warm-up immediately before competition matches or weight training sessions. A group of 22 elite Australian Rules Football players performed 3 different warm-up protocols over 3 testing sessions in a randomized order. The protocols included a series of low load exercises targeting the gluteal muscle group (GM-P), a whole-body vibration (WBV) protocol (WBV-P) wherein the subjects stood on a platform vibrating at 30 Hz for 45 seconds, and a no-warm-up condition (CON). The CMJ testing was performed within 5 minutes of each warm-up protocol on an unloaded Smith machine using a linear encoder to measure peak power output. Peak power production was significantly greater after the GM-P than after both the CON (p < 0.05) and WBV-P (p < 0.01). No significant differences in peak power production were detected between the WBV-P and CON. These results have demonstrated that a low load exercise protocol targeting the gluteal muscle group is effective at acutely enhancing peak power output in elite athletes. The mechanisms for the observed improvements are unclear and warrant further investigation. Coaches may consider incorporating low load exercises targeting the gluteal muscle group into the warm-up of athletes competing in sports requiring explosive power output of the lower limbs.

Is whole-body vibration beneficial for seniors?

Normal aging processes result in losses of functional flexibility and muscular strength, which increase seniors’ fall risk and dependence on others. A relatively new intervention to reduce and/or reverse the adverse effects of aging is whole-body vibration (WBV) exercise. The purpose of this article is to review the established effects of WBV exercise exclusively with the aging population. A systematic search utilizing PubMed and Sport Discus databases uncovered journal articles specific to seniors and whole-body vibration. An extensive hand search supplemented the database results to find other relevant articles. Twenty-seven articles were obtained; all articles have been published in the past 8 years, reflecting the recent and growing interest in this area. Researchers have determined that WBV training can reduce fall risk and improve postural control in seniors. It has also been determined that WBV training can be as effective as conventional resistance training to improve seniors’ lower body strength. However, little is known about the effect of WBV exercise on flexibility and upper body strength in the aging population. More research is required to establish how effective WBV training is on these specific components and how it may affect seniors’ quality of life.

Spinal cord injury and physical activity: preservation of the body

SETTING

Spinal cord injury (SCI) causes devastating loss of function and can result in serious secondary complications. Although significant advances are being made to develop cellular and molecular therapies to promote regeneration, it is important to optimize physical interventions.

OBJECTIVES

The objective of this review was to examine the evidence for the effects of physical rehabilitation strategies on health and fitness, and maintenance of target systems below the level of injury (for example, muscle, bone, circulation).

RESULTS

Exercise appears to be a potent means of achieving these goals, using a variety of strategies.

CONCLUSION

Physical rehabilitation after SCI needs to move beyond the goal of maximizing independence to focus on maintenance of optimum health and fitness as well as maintenance of target system function below the level of injury. Issues requiring further investigation include identification of the optimum dosage of interventions to achieve specific goals, for example, prevention of muscle atrophy and osteoporosis, and development and validation of simple clinical measures to monitor the changes in body composition. Adoption of a classification system for physical interventions and standardized outcome measures would facilitate large-scale observational studies to identify the critical variables contributing to better outcomes.

Low-magnitude whole body vibration with resistive exercise as a countermeasure against cardiovascular deconditioning after 60 days of head-down bed rest

Whole body vibration with resistive exercise is a promising countermeasure against some weightlessness-induced dysfunctions. Our objective was to study whether the combination of low-magnitude whole body vibration with a resistive exercise can prevent the cardiovascular deconditioning induced by a nonstrict 60-day head-down bed rest (Earth Star International Bed Rest Experiment Project). Fourteen healthy men participated in this study. We recorded electrocardiograms and blood pressure waves by means of a noninvasive beat-by-beat measurement system (Cardiospace, integrated by Centre National d'Etudes Spatiales and Astronaut Center of China) during an orthostatic test (20 min of 75-degree head-up tilt test) before and immediately after bed rest. We estimated heart rate, blood pressure, cardiac output, stroke volume, total peripheral resistance, baroreflex sensitivity, and heart rate variability. Low-magnitude whole body vibration with resistive exercise prevented an increase of the sympathetic index (reflecting the sympathovagal balance of cardiac autonomic control) and limited the decrease of the spontaneous baroreflex sensitivity induced by 60 days of head-down bed rest. However, this countermeasure had very little effect on cardiac hemodynamics and did not improve the orthostatic tolerance. This combined countermeasure did not efficiently prevent orthostatic intolerance but prevents changes in the autonomic nervous system associated with cardiovascular deconditioning. The underlying mechanisms remain hypothetical but might involve cutaneous and muscular mechanoreceptors.

Effects of whole body vibration in patients with chronic obstructive pulmonary disease--a randomized controlled trial

INTRODUCTION

To date endurance and strength training are established and evidence-based exercise methods in patients with chronic obstructive pulmonary disease (COPD). There is an unmet need for further research in new and complementary exercise modalities. Additional whole body vibration training during pulmonary rehabilitation may be such a new approach that has not yet been investigated in patients with COPD.

METHODS

Eighty-two patients (65 ± 9 yrs, FEV(1) pred. 38 ± 11%, female 51%) with COPD in GOLD stage III to IV assessed for a 3-week inpatient multidisciplinary rehabilitation program were on top randomly assigned to one of two intervention groups: (1) 3 × 3 min of bilateral dynamic squat exercises on a side-alternating vibration platform at 24-26 Hz three times per week (WBV) and (2) a control group (CON) with the same amount of exercise time without WBV.

RESULTS

Thirty-six patients completed the study in each group. The improvement in 6-min walking distance was significantly higher in the WBV-group when compared to the CON-group (WBV: 64 ± 59 m, CON: 37 ± 52 m with a between-group difference of 27 m [95% CI, 1-53], p = 0.046). The time required for a sit-to-stand test also decreased more markedly in the WBV-group than in the CON-group (WBV: -4.0 ± 4.8 s, CON: -2.0 ± 3.1 s with a between-group difference of -1.9 s [95% CI, -4.0 to 0.1], p = 0.067). Improvements in health-related quality of life were similar in both groups.

CONCLUSIONS

WBV training seems to be a promising new exercise modality for patients with COPD and may enhance the effects of a multidisciplinary rehabilitation program.

Effects of whole body vibration on motor unit recruitment and threshold

Whole body vibration (WBV) has been suggested to elicit reflex muscle contractions but this has never been verified. We recorded from 32 single motor units (MU) in the vastus lateralis of 7 healthy subjects (34 ± 15.4 yr) during five 1-min bouts of WBV (30 Hz, 3 mm peak to peak), and the vibration waveform was also recorded. Recruitment thresholds were recorded from 38 MUs before and after WBV. The phase angle distribution of all MUs during WBV was nonuniform (P < 0.001) and displayed a prominent peak phase angle of firing. There was a strong linear relationship (r = -0.68, P < 0.001) between the change in recruitment threshold after WBV and average recruitment threshold; the lowest threshold MUs increased recruitment threshold (P = 0.008) while reductions were observed in the higher threshold units (P = 0.031). We investigated one possible cause of changed thresholds. Presynaptic inhibition in the soleus was measured in 8 healthy subjects (29 ± 4.6 yr). A total of 30 H-reflexes (stimulation intensity 30% Mmax) were recorded before and after WBV: 15 conditioned by prior stimulation (60 ms) of the antagonist and 15 unconditioned. There were no significant changes in the relationship between the conditioned and unconditioned responses. The consistent phase angle at which each MU fired during WBV indicates the presence of reflex muscle activity similar to the tonic vibration reflex. The varying response in high- and low-threshold MUs may be due to the different contributions of the mono- and polysynaptic pathways but not presynaptic inhibition.

Effects of 3 weeks’ whole body vibration training on muscle strength and functional mobility in hospitalized persons with multiple sclerosis

Background: Exercise therapy in persons with multiple sclerosis (MS) is effective for improving muscle strength and functional mobility.

Objective: To investigate, in MS patients attending an in-patient rehabilitation program, the additional effects of a 3-week exercise program, performed on a whole body vibration platform, on muscle strength and functionality.

Methods: Median Expanded Disability Status Scale (EDSS) of participating patients was 5.5. This randomized controlled trial differentiated a MS control group (n = 17) and two exercise groups performing exercises on a vibration platform (WBV-full group, n = 20) and on the platform additionally covered by a damping mat (WBV-light group, n = 18). Exercise groups performed, during 10 training sessions, six static and dynamic exercises standing on a platform vibrating at high frequency and low amplitude. Isometric muscle strength of quadriceps, hamstrings, tibialis anterior and gluteus medius was measured with a hand-held dynamometer. Functional mobility was measured with Berg Balance Scale (BBS), 3-minute walk test and Timed Get up and Go test.

Results: Eight drop-outs occurred in the exercise groups (WBV-full = 4, WBV-light = 4), but were unrelated to WBV as type of intervention. Across groups, significant time effects were found for all muscle groups. For maximal quadriceps and hamstrings muscle strength, interaction effects were found with post-hoc tests indicating exercise group-significant improvements in the WBV-full group only. Significant time effects were found for all functional tests. Improvements on the BBS and 3-minute walk test were larger in training than in control groups, but no significant interactions were found.

Conclusions: A 3-week exercise program on a vibration plate significantly improved muscle strength, but not functionality, in persons with MS.

The sports performance application of vibration exercise for warm-up, flexibility and sprint speed

Since the turn of the 21st century, there has been a resurgence of vibration technology to enhance sport science especially for power and force development. However, vibration exercise has been trialled in other areas that are central to athlete performance such as warm-up, flexibility and sprint speed. Therefore, the aim of this review was to attempt to gain a better understanding of how acute and short-term vibration exercise may impact on warm-up, flexibility and sprint speed. The importance of warming up for sporting performance has been well documented and vibration exercise has the capability to be included or used as a standalone warm-up modality to increase intramuscular temperature at a faster rate compared to other conventional warm-up modalities. However, vibration exercise does not provide any additional neurogenic benefits compared to conventional dynamic and passive warm-up interventions. Vibration exercise appears to be a safe modality that does not produce any adverse affects causing injury or harm and could be used during interval and substitution breaks, as it would incur a low metabolic cost and be time-efficient compared to conventional warm-up modalities. Acute or short-term vibration exercise can enhance flexibility and range of motion without having a detrimental effect on muscle power, however it is less clear which mechanisms may be responsible for this enhancement. It appears that vibration exercise is not capable of improving sprint speed performance; this could be due to the complex and dynamic nature of sprinting where the purported increase in muscle power from vibration exercise is probably lost on repeated actions of high force generation. Vibration exercise is a safe modality that produces no adverse side effects for injury or harm. It has the time-efficient capability of providing coaches, trainers, and exercise specialists with an alternative modality that can be implemented for warm-up and flexibility either in isolation or in conjunction with other conventional training methods.

Effects of whole-body vibration on postural control in elderly: a systematic review and meta-analysis

BACKGROUND

This systematic review was performed to summarize the current evidence for whole body vibration (WBV) interventions on postural control in elderly.

METHODS

English and German language papers in Medline, PEDro, Cinahl and the Cochrane databases were searched. Two reviewers extracted data on patients' characteristics, type of WBV intervention and outcomes. Two independent reviewers rated the methodological quality of these studies. Data were pooled using random-effects meta-analysis.

RESULTS

Fifteen papers reporting quantitative data were included. Results from 15 papers could be pooled for a meta-analysis. The studies involved 933 participants. In 7 studies the authors investigated the effects of vibration plates generating vertical sinusoidal vibrations (VS-WBV) and 7 papers described the use of side-alternating sinusoidal vibrations (SS-WBV). One study investigated both VS-WBV and SS-WBV.Weak to moderate evidence of an overall effect as a result of VS-WBV and SS-WBV was observed for (a) static balance for post-intervention values with a standardized mean difference (SMD) -0.06, 95% CI -0.31 to 0.18 and for change values SMD -0.26, 95% CI -1.09 to 0.57, and (b) dynamic balance for post-intervention-values SMD -0.34, 95% CI -0.60 to -0.08. For functional balance (c) an overall outcome for post-intervention values with SMD of 0.34, 95% CI -0.19 to 0.87 was found.

CONCLUSIONS

The 15 studies reviewed were of moderate methodological quality. In summary, SS-WBV seems to have a beneficial effect on dynamic balance in elderly individuals. However, the current results should be interpreted with caution because of the observed heterogeneity of training parameters and statistical methods. Future studies are warranted to evaluate the effects of WBV on postural control in an elderly population.

Systematically controlling for the influence of age, sex, hertz and time post-whole-body vibration exposure on four measures of physical performance in community-dwelling older adults: a randomized cross-over study

Though popular, there is little agreement on what whole-body vibration (WBV) parameters will optimize performance. This study aimed to clarify the effects of age, sex, hertz and time on four physical function indicators in community-dwelling older adults (N = 32). Participants were exposed to 2 min WBV per session at either 2 Hz or 26 Hz and outcome measures were recorded at 2, 20 and 40 min post-WBV. Timed get up-and-go and chair sit-and-reach performances improved post-WBV for both sexes, were significantly different between 2 Hz and 26 Hz treatments (P ≤ 0.05) and showed statistically significant interactions between age and gender (P ≤ 0.01). Counter movement jump and timed one-legged stance performances showed a similar but non-significant response to 2 Hz and 26 Hz treatments, though male subjects showed a distinct trended response. Age and gender should be statistically controlled and both 2 Hz and 26 Hz exert a treatment effect.

Expression and regulation of Homer in human skeletal muscle during neuromuscular junction adaptation to disuse and exercise

Protein calcium sensors of the Homer family have been proposed to modulate the activity of various ion channels and nuclear factor of activated T cells (NFAT), the transcription factor modulating skeletal muscle differentiation. We monitored Homer expression and subcellular localization in human skeletal muscle biopsies following 60 d of bedrest [Second Berlin Bedrest Study (BBR2-2)]. Soleus (SOL) and vastus lateralis (VL) biopsies were taken at start (pre) and at end (end) of bedrest from healthy male volunteers of a control group without exercise (CTR; n=9), a resistive-only exercise group (RE; n=7), and a combined resistive/vibration exercise group (RVE; n=7). Confocal analysis showed Homer immunoreactivity at the postsynaptic microdomain of the neuromuscular junction (NMJ) at bedrest start. After bedrest, Homer immunoreactivity decreased (CTR), remained unchanged (RE), or increased (RVE) at the NMJ. Homer2 mRNA and protein were differently regulated in a muscle-specific way. Activated NFATc1 translocates from cytoplasm to nucleus; increased amounts of NFATc1-immunopositive slow-type myonuclei were found in RVE myofibers of both muscles. Pulldown assays identified NFATc1 and Homer as molecular partners in skeletal muscle. A direct motor nerve control of Homer2 was confirmed in rat NMJs by in vivo denervation. Homer2 is localized at the NMJ and is part of the calcineurin-NFATc1 signaling pathway. RVE has additional benefit over RE as countermeasure preventing disuse-induced neuromuscular maladaptation during bedrest.

Changes in lower extremity muscle function after 56 days of bed rest

Preservation of muscle function, known to decline in microgravity and simulation (bed rest), is important for successful spaceflight missions. Hence, there is great interest in developing interventions to prevent muscle-function loss. In this study, 20 males underwent 56 days of bed rest. Ten volunteers were randomized to do resistive vibration exercise (RVE). The other 10 served as controls. RVE consisted of muscle contractions against resistance and concurrent whole-body vibration. Main outcome parameters were maximal isometric plantar-flexion force (IPFF), electromyography (EMG)/force ratio, as well as jumping power and height. Measurements were obtained before and after bed rest, including a morning and evening assessment on the first day of recovery from bed rest. IPFF (−17.1%), jumping peak power (−24.1%), and height (−28.5%) declined ( P < 0.05) in the control group. There was a trend to EMG/force ratio decrease (−20%; P = 0.051). RVE preserved IPFF and mitigated the decline of countermovement jump performance (peak power −12.2%; height −14.2%). In both groups, IPFF was reduced between the two measurements of the first day of reambulation. This study indicates that bed rest and countermeasure exercises differentially affect the various functions of skeletal muscle. Moreover, the time course during recovery needs to be considered more thoroughly in future studies, as IPFF declined not only with bed rest but also within the first day of reambulation. RVE was effective in maintaining IPFF but only mitigated the decline in jumping performance. More research is needed to develop countermeasures that maintain muscle strength as well as other muscle functions including power.