whole body vibration

Bus drivers are exposed to harmful agents such as noise and vibration which may led to increasing the level of job stress among them. The aim of this study was to evaluation of job stress among urban bus drivers with respect to daily noise and vibration exposures.

This cross-sectional study carried out with participation of 103 urban bus drivers in Hamadan, 2020. The drivers' exposure to noise and vibration were measured using Svan 104 and Svan 106, respectively. The job stress was measured through Phillippe L. Rice questionnaire. Data analysis preformed using SPSS 24 and the significant levels of 0.05.

The mean exposure of drivers with noise was 79.50±3.51 dB. Their exposure with whole body vibrations (WBV) and hand-arm vibrations (HAV) were 0.62±0.16 and 0.44±0.06 m/s2, respectively. Most drivers (87.4 percent) had sever job stress. A significant positive correlation was observed between noise and job stress; whereas, there was no significant correlation between WBV and HAV with job stress. 

Regarding high prevalence of severe job stress among bus drivers and the positive correlation between noise and job stress, it is highly recommended that the noise exposure were subside through periodic services and maintenance as well as applying new buses instead of the old ones.

Studies show that in many cases, environmental hazardous agents such as heat, noise, as well as chemical pollutants cause adverse health effects through the mechanism of oxidative stress. This study has examined the effect of exposure to noise and whole-body vibration (WBV) on some parameters of oxidative stress (enzyme superoxide dismutase (SOD), total antioxidant capacity (TAC), and malondialdehyde (MDA)) of workers in a foundry industry.

The workers were selected based on the calculations related to the sample size and taking into account the inclusion criteria as well as completing the informed consent form. The level of exposure to noise and WBV was measured according to ISO 9612 and ISO 2631, respectively. For each worker, the time-weighted average was calculated. The level of exposure of workers to the studied stressors was divided into three categories: low, medium, and high. The blood samples were taken from all participants between 7-9 am. Then, via ELISA method according to the protocol of the kit manufacturer, the samples were prepared and analyzed. Univariate analysis of variance was performed to determine the “effect size” of each physical stressors on the studied parameters.

The mean levels of MDA, SOD, and TAC among participants were 22.48 (11.19) nmol / ml, 61.28 (10.97) U / ml, and 1.64 (0.90) mM, respectively. Among the exposure variables, noise had the largest effect on MDA level (B = 0.090), which was not statistically significant (P = 0.865). WBV had the largest effect on SOD level (B = -1.469) which was statistically significant (P = 0.016). None of the studied variables had a significant effect on the TAC level; however, among the exposure variables, the greatest effect was related to WBV (B = -0.077; P = 0.133).

The effect of noise on oxidative stress parameters was not statistically significant. The effect of whole-body vibration on oxidative stress parameters except SOD was not statistically significant. Noise and WBV had increasing effect on MDA and decreasing one on SOD and TAC levels.

Whole body vibration (WBV) is a safe and effective method to improve balance and muscle strength. Considering to the effect of foot longitudinal arch on dynamic balance, and the effectiveness of WBV in improving balance, the present study aims to assess the effects of WBV on dynamic balance of patients with flexible flatfoot.

In this randomized clinical trial, 80 patients with flexible flatfoot; 40 aged <18 years (Mean±SD age= 15.25±1.24) and 40 aged >20 (Mean±SD age= 22.57±1.48). They were randomly divided into two intervention groups of <18 and >20 years and two control groups of <18 and >20 years. The intervention groups received four weeks of WBV. In the control groups, no intervention was carried out. The fatigue was induced by running on a treadmill at different speeds and inclinations according to the Bruce protocol. Dynamic balance was assessed using the Biodex Balance System at anterior-posterior and medial-lateral directions and in overall.

The repeated measures analysis of variance and Bonferroni test results showed that the mean dynamic balance in overall and at anterior-posterior and medial-lateral directions were significantly increased in the intervention groups compared to the control groups (P<0.001). Moreover, the dynamic balance showed a significant increase in the intervention group aged <18 years compared to the intervention group aged >20 years (P<0.001).

The WBV can be used to improve the dynamic balance of people with flexible flatfoot even in fatigue conditions.

One of the most common manifestations of diabetic peripheral neuropathy is postural impairment and proprioception deficits. Whole Body Vibration (WBV) is a relatively new somatosensory stimulation, the effects of which on balance and proprioception in patients with diabetic neuropathy have not been adequately studied. This study aimed to investigate the effects of WBV on balance and proprioception of the ankle joint in patients with diabetic neuropathy.

This clinical trial study was conducted on 30 patients with diabetic neuropathy who were enrolled based on inclusion and exclusion criteria. The patients were randomly assigned to the intervention and control groups (15 patients in each group). The WBV group was subjected to WBV with a frequency of 30 Hz and an amplitude of 2 mm for 6 weeks and twice a week. Postural stability, balance indices, and ankle proprioception were measured before and after the intervention with the Biodex Balance System, Berg Balance Scale (BBS), and Biodex Isokinetic Dynamometer, respectively.

The results of this study showed that the static and dynamic postural stability indices in different axes with eyes open showed a significant improvement in the intervention group (except for the dynamic stability index of the mediolateral axis). The repositioning error angle also showed a significant decrease in the maximum inversion minus 5 °. But the BBS and repositioning error angle at 15 ° inversion did not change significantly after 6 weeks of intervention.

WBV can improve postural stability and ankle position sense in people with diabetic neuropathy. Clinical improvements in functional balance were also observed in these patients. WBV may be suggested to prevent progressive balance changes in diabetic patients.

Vibration, especially whole body vibration, is one of the most important physical harmful factors in industrial environments as well as vehicles. Exposure to whole-body vibration can cause different mental and physiological reactions in humans. This study aimed to investigate the effect of exposure to whole body vibration on the mental performances of 20-29 years old males in laboratory conditions.

In this research, 32 male students of Shahid Beheshti University of Medical Sciences with an average age of 22.19±2.6 years and a BMI of 20.23±2.21 kg/m2 participated. The acceleration of the whole body vibration was considered at three levels of low (0.53 m/s2), moderate (0.81 m/s2) and high (1.12 m/s2) according to the ISO 2631 standard at a frequency of 3-7 Hz. The mental functions of each subject were examined first in the vibration-free state and then at different vibration acceleration levels using the IVA (Integrated Visual and Auditory Continues) tool.  The heart rate of the subjects was also recorded by a digital heart rate monitor.

The results of this study showed that with increasing whole body vibration acceleration, visual and auditory attention decreased significantly (P<0.001). In addition, the heart rate and response time of the subjects significantly increased (P<0.001).

The results showed that whole body vibration is an effective factor in reaction time, mental functions and physiological parameters, which can reduce the accuracy of the work.

Little attention has been paid to the effects of combined exposure to noise and vibration. Exposure to noise and vibration can effect stress hormones and may lead to high blood pressure and cardiovascular disorders. This study aims to investigate the effects of noise and vibration on urinary Metanephrine and Normetanephrine among men.

In this experimental study, 30 male students were deemed eligible for entry. Background variables such as temperature, light intensity, sound pressure level and vibration acceleration (before and after exposure) were measured throughout each experiment. Participants were randomly exposed to two noise levels and two vibration accelerations for 30 minutes in a combined and independent exposure condition. Urine samples were taken an hour before and an hour after exposure. Metanephrine and Normetanephrine levels were measured using the ELISA method and a specialized Metanephrine/Normetanephrine urinary measurement kit. A repeated measures regression with a Generalized Estimating Equations (GEE) approach was applied for data analysis.

The exposure to noise (at 85 and 91 dB(A)) and independent exposure to whole body vibration at 1.85 m/s2 caused an increase in Normetanephrine and a decrease in Metanephrine concentration although these changes were not statistically meaningful (P>0.05). Combined exposure to noise and vibration caused an increase in Metanephrine and Normetanephrine concentration. These changes were also not statistically significant (P>0.05).

Study subjects’ stress hormone concentrations changed when exposed to noise but did not follow a particular trend. Short term exposure (30 minutes) did not have a distinguish effect on urinary Metanephrine and Normetanephrine concentrations. Therefore, urinary Metanephrine and Normetanephrine concentrations cannot be considered appropriate indicators for noise and whole body vibration exposure.

Road traffic noise is one of the most common sources of environmental noise which has various effects on mental and physical health, impaired daily life function and cognitive performance. Vibration is another achievement of industrial development that is accompanied by noise in most work environments. Vibration transmitted from road surface to vehicles and drivers may interfere with activities, affect their comfort level and reduce attention. The purpose of this study was to compare the effect of independent and simultaneous exposure to traffic noise and whole body vibration on visual and auditory attention and control response of males using Integrated Visual Auditory Performance Test (IVA + PLUS).

The study population included 24 male students aged 18 to 30 years old in Shahid Beheshti University of Medical Sciences who had inclusion criteria for the study. The experiments were performed in 4 steps randomly in one day for each person in the acoustic room and in total, 96 experimental runs (24 runs per step) were performed. Inclusion criteria included: Students in the age group of 18-30 years, no history of underlying diseases including respiratory problems, skin disorders, sleep and cardiovascular disorders and other health problems affecting onechr('39')s muscular and brain health, no short term illnesses during the trial (colds, diarrhea and vomiting), no history of upper limb musculoskeletal disorders, hearing loss less than dBA27, visual acuity above (7/10), no smoking addiction and drugs and alcohol, no use of hypnotic drugs and CNS attenuating drugs during the test period, not  being over sensitive to sound according to Weinstein noise sensitivity questionnaire and getting a score of 22 or below in General Health Questionnaire, which reflects the health of the individuals. Exclusion criteria also included: a personchr('39')s unwillingness to continue participating because of the long studychr('39')s time and people who did not meet the above criteria. Subjects did the IVA test (data recorded including scores of total attention and response control scores) in background conditions (sound level dBA 27 and vibration acceleration zero), then they were exposed to individual and combined noise level of 55 dBA (as the permissible sound pressure level at outdoors) and the vibration acceleration of 0.65 m/s2 (as the average acceleration vibration in the Iranian vehicles). In this study, a vibration simulator was used to generate a vibration in the x, y, and z axes at different frequencies and intensities, either sinusoidal or randomly using a vibrating engine. The Italian OLI VIBRATOR MVE.440 / 2M vibrating engine was attached to the seat using a metal stand. The Ic5 inverter was used to adjust the vibration frequency and acceleration and the whole body vibration meter according to ISO 2631 was used to ensure the calibration of the vibration produced by the vibration simulator. The noise used in this study was generated by the signal software with combining the desired frequency and these computer-generated audio files were performed in the Cool edit tool software during the test. One of the features of this software is the ability to edit the sound in intensity at different frequencies, and by continuously monitoring noise in the acoustic room, the volume of the noise can be controlled at the desired frequencies. During the exposure, the intensity of noise within the individualchr('39')s hearing range, inside the acoustic room was controlled by a calibrated B&K 2238 Sound Level Meter. The IVA is an 8-minute visual and auditory continuous performance test that assesses total attention and response control scores. The task of the participant is to react when the number 1 is seen or heard and to click on the mouse once, and don’t react when the number 2 is seen or heard. The task type assigned to the participants was "simple", its physical workload was "light". Participants signed written consent form and filled demographic information form, general health questionnaire (GHQ-28), and Weinstein noise sensitivity scale. Audiometric and the E eye chart tests were done for hearing and visual acuity testing. To determine the individual and combined effect of noise and whole body vibration on attention and response control, regression analysis of repeated measures using generalized estimating equations with first order autoregressive process was used.

The mean (±SD) age of the participants were 23.41 ± 2.99 years. In the visual test and in the background vibration acceleration, the mean scores of attention has been increased with increasing traffic noise from 27 to 55 dBA and the response control score has been decreased (P = 0.79 and P = 0.1, respectively). At the background noise level, mean scores of attention and response control have been increased with increasing vibration acceleration from zero to 0.65 m/s2 (P = 0.49 and P = 0.59, respectively),). In combined exposure condition with noise level 55 dBA and vibration acceleration of 0.65 m/s2, the mean score of attention decreased compared to background ones (P= 0.95), and the response control score increased compared to background ones (P= 0.72). In the auditory test and in the background vibration acceleration, the mean scores of attention and response control have been increased by increasing the traffic noise from 27 to 55 dBA (P = 0.02 and P = 0.13, respectively), At the background noise level, mean scores of attention were significantly reduced by increasing the vibration acceleration from zero to 0.65 m/s2 (P =0.01). Mean scores of response control has been increased with increasing vibrational acceleration from zero to 0.65 m/s2 (P=0.74). In combined exposure condition, the mean scores of attention were significantly lower than background ones (P =0.01), and the response control score has been increased compared to the background ones (P= 0.09).

Similar results were found regarding the combined effect of noise level 55 dBA and vibration acceleration of 0.65 m/s2 on the total level of attention and response control in visual and auditory tests. So that the simultaneous increase in noise level and vibration acceleration relative to the background condition leaded to decrease in the total score of attention in both visual and auditory dimensions. However, in the mentioned conditions, the response control score has been increased in both visual and auditory tests.  It seems that the score of response control, which in some way expresses the ability to sustain attention and the reaction speed during the test, has been increased as a result of noise motivation theory and the positive short-term effects of vibration acceleration. In general, whole body vibration in low to moderate acceleration level and low level of noise may improve cognitive performance in a short time, however, definitive conclusions are subject to doing the systematic and comprehensive studies.

The available data indicate that there is a relationship between proprioception deficit and low back pain. For this reason, proprioception exercises are usually part of the rehabilitation protocols for these patients. Previous studies revealed that whole body vibration (WBV) can improve muscle performance and proprioception. The aim of this study was to investigate effect of WBV on trunk proprioception in non-specific chronic low back pain (NSCLBP).

In this randomized clinical trial study, 50 patients with NSCLBP were enrolled. They were randomly assigned to the WBV and control groups. Correspondingly, patients in the experimental group received WBV with frequency 20Hz and acceleration 3-17 g for 360 second in 6 repetitions, and patients in the control group were placed on device at the same position and time, with no vibration. Trunk repositioning error in 30%,60% maximal flexion of lumbar region and in neutral position was measured with Dual Digital inclinometer, before intervention and immediately after 20 minutes.

By matching the original effect of measurement conditions (p<0.001) and its interactive effect with group (p = 0.008), there was a significant difference between two groups immediately after the intervention (p=0.027).

WBV with low frequency can improve trunk proprioception in individual with non-specific chronic low back pain. So, it can be introduced as a novel physical therapy intervention for these patients.

Foot function depends on its shape. Flat Foot is one of the longitudinal arch changes of the foot that is involved in maintaining body balance. Whole Body Vibration is an effective method for applying sinusoidal mechanical oscillations. The purpose of the present study was to investigate the effects of whole body vibration on static balance in flat foot during and after the developing age after fatigue. In the current study, 80 patients with Flat Foot (40 females and 40 males) including 40 females and males under 18 with the mean age of 15±1/24 and 40 females and males over 20 with the mean age of 22/57±2/48 were randomly divided into intervention and control groups. Intervention group received four weeks of WBV training. In the control group, including both under 18 and over 20-year-old participants, no intervention was carried out. In this group, the participants followed their daily activities. The fatigue protocol performed on the treadmill and Static balance tests was assessed using Biodex Balance System indices including total, anterior-posterior, and medial-lateral. The results of between group analyses indicated that for the group under 18, all aforementioned variables significantly improved in comparison with those over 20. Whole Body Vibration can be used to improve the static balance of flat foot even after fatigue.

Operators of construction vehicles are constantly exposed to whole body vibration, which can lead to musculoskeletal disorders. The aim of present study was to evaluate the impact of exposure to whole body vibration in operators and its relation to musculoskeletal disorders. This study is a descriptive-analytical study. Using easy sampling, 89 operators from 6 types of heavy vehicles (Bulldozer, Tipper Truck, Heavy Vibrator Roller, Light Vibrator Roller, Pecker and Loader) were included in two construction projects. To evaluate exposure to whole body vibration, different vibration indices (effective acceleration, peak factor and vibrational dose) were measured according to ISO 2631 and SVAN 958 vibrometer. The Body Map Questionnaire was used to assess the musculoskeletal disorders. Data were analyzed using Kolmogorov-Smirnov tests, one-way ANOVA, Pearson correlation and multivariate regression (significance level less than 0.05). The results of this study showed that exposure to whole body vibration in Bulldozer (2.25 m/s2), Tipper Truck (0.98 m/s2), Heavy Vibration Rollers (3.20 m/s2), Light Vibration Rollers (3.45 m/s2) Pecker (4.11 m/s2) and Loader (1.2 m/s2) are more than the daily exposure to OEL. There was a significant and direct relationship between exposure to vibration, underlying factors and musculoskeletal disorders. The present study confirms the potential health hazards for operators of construction vehicles. Therefore, engineering and management controls are recommended, including installation of appropriate vibration insulators on seats, training courses, changing jobs of individuals with a long exposure to vibration, rotating work schedules, using gloves, flooring and vibration damping pads and create monitoring protocols on work.

Delayed onset muscle soreness (DOMS) that occurs after eccentric exercise can cause limitations in sports activities, especially in professional athletes. Relatively, different studies have been designed to prevent and control the consequence of the DOMS. Previous studies have confirmed the impact of local vibration (LV) and whole body vibration (WBV) to reduce the symptoms of DOMS. However, the effects of these two methods have not been compared in any study. The aim of the present research was to compare the effects of LV and WBV to prevent the symptoms of DOMS.

Forty-nine typical, non-athletic volunteers were assigned randomly into two experimental (LV and WBV) and a control groups. The VT group received 50 Hz vibration on the left and right quadriceps, hamstring and calf muscles for 1 min. The WBVT group, the intervention was one minute of vibration (35Hz) using a vibratory platform with 100° of knee flexion. The control group did not receive any intervention. Then, three groups walked downhill on a 30° declined treadmill at a speed of 4 km/hour. The DOMS symptoms (isometric maximum voluntary contraction force of quadriceps muscles, DOMS level by visual analogue scale, thigh circumference and Serum Creatine Kinase) were measured before and 48 hours after the intervention.

The WBV and LV groups showed significant changes in the DOMS symptoms in the form of less maximal isometric and voluntary strength loss, lower creatine kinase levels, and less muscle soreness (P <0 .05) compared with the control group. However, the intensity of DOMS was not significantly different between the WBV and LV groups (p>0.05).

This study showed that the LVand WBV had same effects on the DOMS symptoms. The LV procedure is more convenient and more economical to be used by the athletes, its application is recommended.

Whole body vibration (WBV) in some studies has been suggested as an intervention for improving body fat. The purpose of current study is to review systematically the studies that have evaluated the effect of WBV on body fat. In this systematic review a search within the period of 2001-2017 was performed at PubMed, Cochrane Library, Science Direct, Web of Science, Ovid, Scopus, Google Scholar, Medline, Clinical Trial.gov, ProQuest, Iranmedex, Irandoc, Magiran, SID databases. In this process, studies that had investigated the effects of WBV on body fat were included. PEDro quality scale was used for the assessment of included studies. 9 Out of 1006 studies were selected based on inclusion criteria. Many differences between the articles in the target samples, methodology etc was observed. Overall, it has been shown that this intervention cannot significantly affect the amount of whole body fat, while its effects are locally on body fat. WBV alone doesn’t have more and significant benefits on body fat, as compared to training exercises. Conclusuvely, WBV with exercise can have greater effects on body fat, than WBV alone. WBV cannot affect the amount of whole body fat and its effects are more localized. It seems that strong determination of the effect of WBV on the body fat level requires homogeneous and high-quality studies be conducted in this field to allow the meta-analysis study.