Transmission of vibration from a vibrating plate to the head of standing people

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.

Transmission of fore-and-aft floor vibration to the spine and head of standing people

Sixteen standing male participants were subjected to fore-and-aft sinusoidal vibration with peak magnitude and frequency in the range 0.44-4.431 ms-2 and 2-6 Hz, respectively. The fore-and-aft, lateral and vertical transmissibilities to the first dorsal vertebra (T1), eighth dorsal vertebra (T8), twelfth dorsal vertebra (T12), fourth lumbar vertebra (L4) and head were measured. Large inter-participant variability was observed in the transmissibilities at all locations. Nevertheless, peaks in the range 3-4.5 Hz were identified at all locations, implying a whole-body resonance in this frequency range. The response was found dominant in the mid-sagittal plane as the lateral transmissibility showed low values. Below 4.5 Hz, the fore-and-aft transmissibility increased with moving from caudal to cranial locations of the upper body. However, at higher frequencies, the opposite trend was observed. The results can be used for developing models that may help understand how vibration affects health and comfort.

Whole body vibration therapy and cognitive functions: a systematic review

Whole Body Vibration has been found to induce physiological changes in human subjects, improving their neuromuscular, respiratory and cardiovascular functions. Evidence from animal research prove that whole-body vibration appears to induce changes in molecular and cellular levels to alter cognitive functions in mice. There is evolving evidence for a potential value of whole body vibration in improving cognition and preventing the development of age-related cognitive disorders in humans. However, literature on the biological consequences of whole-body vibration on the human brain is scanty. If so, gathering the available evidences would help decide the possibility of designing appropriate whole-body vibration protocols to extend its application to induce neurocognitive enhancement and optimize its effects. Therefore, a systematic review of the literature was performed, consulting the ProQuest, MEDLINE and Scopus bibliographic databases, to summarize the available scientific evidence on the effects of whole-body vibration on cognitive functions in adults. Results of the review suggest that whole-body vibration therapy enhances a wide spectrum of cognitive functions in adults although there isn't enough evidence available yet to be able to design a standardized protocol to achieve optimum cognitive enhancement.

Vibration transmitted to the hands of power drill operators: Effect of arm posture and type of drilled material

This study investigated the effect of the arm posture and the type of material on the vibration measured at the hands during drilling operation. An experiment was conducted using three different materials (concrete, steel, and wood) and two different arm postures characterized as 90° and 180° angle between the upper arm and forearm. Six male subjects stood on a force platform to measure and control the feed force during the drilling operation. The vibration was measured at the interface between the drill and both hands. The results showed that the effect of arm posture was dependent on the type of material being drilled. For example, drilling in concrete yielded higher frequency-weighted acceleration with the 90° arm posture than the 180° posture while drilling in wood showed an opposite trend. The results tend to suggest no correlation between the material hardness and the vibration at the hands. Higher vibration was also observed at the right hand than the left hand. It is recommended to not use the vibration emission data reported by manufacturers of power tools to evaluate incidences of hand-arm vibration syndrome (HAVS) but to rely on real measurements taken in the field under typical operating conditions.

Short-term effects of side-alternating Whole-Body Vibration on cognitive function of young adults

Recent research in rodents and humans revealed that Whole-Body Vibration (WBV) is beneficial for cognitive functions. However, the optimal WBV conditions are not established: contrary to vertical WBV, side-alternating WBV was not investigated before. The present study investigated the short-term effects of side-alternating WBV in standing and sitting posture on specific cognitive function of young adults. We used a balanced cross-over design. Sixty healthy young adults (mean age 21.7 ± 2.0 years, 72% female) participated. They were exposed to three bouts of two-minute side-alternating WBV (frequency 27 Hz) and three control conditions in two different sessions. In one session a sitting posture was used and in the other session a standing (semi-squat) posture. After each condition selective attention and inhibition was measured with the incongruent condition of the Stroop Color-Word Interference Test. WBV significantly (p = 0.026) improved selective attention and inhibition in the sitting posture, but not in the standing posture. The sitting posture was perceived as more comfortable, joyous and less exhaustive as compared to the standing posture. This study demonstrated that side-alternating WBV in sitting posture improves selective attention and inhibition in healthy young adults. This indicates that posture moderates the cognitive effect of WBV, although the effects are still small. Future studies should focus on the working mechanisms and further optimization of settings, especially in individuals who are unable to perform active exercise.

The effect of vibration on kinematics and muscle activation during cycling

Vibration has the potential to compromise performance in cycling. This study aimed to investigate the effects of vibration on full-body kinematics and muscle activation time series. Nineteen male amateur cyclists (mass 74.9 ± 5.9 kg, body height 1.82 ± 0.05 m, Vo2max 57 ± 9 ml/kg/min, age 27 ± 7 years) cycled (216 ± 16 W) with (Vib) and without (NoVib) vibration. Full-body kinematics and muscle activation time series were analysed. Vibration did not affect lower extremity joint kinematics significantly. The pelvic rotated with vibration towards the posterior direction (NoVib: 22.2 ± 4.8°, Vib: 23.1 ± 4.7°, p = 0.016, d = 0.20), upper body lean (NoVib: 157.8 ± 3.0°, Vib: 158.9 ± 3.4°, p = 0.001, d = 0.35) and elbow flexion (NoVib: 27.0 ± 8.2°, Vib: 29.4 ± 9.0°, p = 0.010, d = 0.28) increased significantly with vibration. The activation of lower extremity muscles (soleus, gastrocnemius lat., tibialis ant., vastus med., rectus fem., biceps fem.) increased significantly during varying phases of the crank cycle due to vibration. Vibration increased arm and shoulder muscle (triceps brachii, deltoideus pars scapularis) activation significantly over almost the entire crank cycle. The co-contraction of knee and ankle flexors and extensors (vastus med. - gastrocnemius lat., vastus med. - biceps fem., soleus - tibialis ant.) increased significantly with vibration. In conclusion vibrations influence main tasks such as propulsion and upper body stabilization on the bicycle to a different extent. The effect of vibration on the task of propulsion is limited due to unchanged lower body kinematics and only phase-specific increases of muscular activation during the crank cycle. Additional demands on upper body stabilization are indicated by adjusted upper body kinematics and increased muscle activation of the arm and shoulder muscles during major parts of the cranking cycle.

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

Simple Summary

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

Abstract

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

Biodynamic Responses to Whole-Body Vibration Training: A Systematic Review

In recent years, whole-body vibration (WBV) training has received an increasing interest in the sports and medical fields. However, there has been inconsistency among several studies regarding the effect of WBV training on the human body, which is partly due to the lack of the existence of guidelines for using WBV training machines. To understand the effect of WBV training on the human body and build the needed regulations, it is essential first to understand the biodynamic responses to vibration which represent how vibration is transmitted to and through the human body. The purpose of this study is to systematically review previous studies that measured biodynamic responses when using WBV training machines to highlight inconsistencies in their results and provide possible reasons for them. An extensive literature search was performed on the SCOPUS database to obtain relevant studies. One hundred and fifty-six potentially relevant studies were obtained but after further screening, 23 papers from 2007 to 2020 met inclusion criteria and were included in the study. The papers were analysed with respect to acceleration, transmissibility, interface force, and apparent mass during different vibration settings, body posture, age, and sex. Results and conflicts among studies were highlighted and possible explanations for the inconsistency were provided.

Transmission of whole body vibration - Comparison of three vibration platforms in healthy subjects

The potential of whole body vibration (WBV) to maintain or enhance musculoskeletal strength during ageing is of increasing interest, with both low and high magnitude WBV having been shown to maintain or increase bone mineral density (BMD) at the lumbar spine and femoral neck. The aim of this study was to determine how a range of side alternating and vertical WBV platforms deliver vibration stimuli up through the human body. Motion capture data were collected for 6 healthy adult participants whilst standing on the Galileo 900, Powerplate Pro 5 and Juvent 100 WBV platforms. The side alternating Galileo 900 WBV platform delivered WBV at 5-30 Hz and amplitudes of 0-5 mm. The Powerplate Pro 5 vertical WBV platform delivered WBV at 25 and 30 Hz and amplitude settings of 'Low' and 'High'. The Juvent 1000 vertical WBV platform delivered a stimulus at a frequency between 32 and 37 Hz and amplitude 10 fold lower than either the Galileo or Powerplate, resulting in accelerations of 0.3 g. Motion capture data were recorded using an 8 camera Vicon Nexus system with 21 reflective markers placed at anatomical landmarks between the toe and the forehead. Vibration was expressed as vertical RMS accelerations along the z-axis which were calculated as the square root of the mean of the squared acceleration values in g. The Juvent 1000 did not deliver detectable vertical RMS accelerations above the knees. In contrast, the Powerplate Pro 5 and Galileo 900 delivered vertical RMS accelerations sufficiently to reach the femoral neck and lumbar spine. The maximum vertical RMS accelerations at the anterior superior iliac spine (ASIS) were 1.00 g ±0.30 and 0.85 g ±0.49 for the Powerplate and Galileo respectively. For similar accelerations at the ASIS, the Galileo achieved greater accelerations within the lower limbs, whilst the Powerplate recorded higher accelerations in the thoracic spine at T10. The Powerplate Pro 5 and Galileo 900 deliver vertical RMS accelerations sufficiently to reach the femoral neck and lumbar spine, whereas the Juvent 1000 did not deliver detectable vertical RMS accelerations above the knee. The side alternating Galileo 900 showed greater attenuation of the input accelerations than the vertical vibrations of the Powerplate Pro 5. The platforms differ markedly in the transmission of vibration with strong influences of frequency and amplitude. Researchers need to take account of the differences in transmission between platforms when designing and comparing trials of whole body vibration.

Managing Vibration Training Safety by Using Knee Flexion Angle and Rating Perceived Exertion

Whole-body vibration (WBV) is commonly applied in exercise and rehabilitation and its safety issues have been a major concern. Vibration measured using accelerometers can be used to further analyze the vibration transmissibility. Optimal bending angles and rating of perceived exertion (RPE) evaluations have not been sufficiently explored to mitigate the adverse effect. Therefore, the aims of this study were to investigate the effect of various knee flexion angles on the transmissibility to the head and knee, the RPE during WBV exposure, and the link between the transmissibility to the head and the RPE. Sixteen participants randomly performed static squats with knee flexion angles of 90, 110, 130, and 150 degrees on a WBV platform. Three accelerometers were fixed on the head, knee, and center of the vibration platform to provide data of platform-to-head and platform-to-knee transmissibilities. The results showed that the flexion angle of 110 degrees induced the lowest platform-to-head transmissibility and the lowest RPE (p < 0.01). A positive correlation between RPE and the platform-to-head transmissibility was observed. This study concluded that a knee flexion of about 110 degrees is most appropriate for reducing vibration transmissibility. The reported RPE could be used to reflect the vibration impact to the head.

Tri-axial transmissibility to the head and spine of seated human subjects exposed to fore-and-aft whole-body vibration

Previous studies have quantified the biodynamic responses to vibration with more focus on vertical vibration than horizontal vibration. This study reports the transmissibility to the head and spine measured under whole-body fore-and-aft vibration. Sixteen seated male subjects were exposed to sinusoidal fore-and-aft vibration with magnitudes 0.311-2.426 ms^-2 r.m.s. and frequency range 2-6 Hz. The fore-and-aft (Txx), lateral (Txy) and vertical (Txz) transmissibilities to the head, three locations on the thoracic spine (T1, T8, T12) and L4 were measured. Txx, Txy and Txz showed high inter-subject variability at all locations. A peak in the range 2-2.4 Hz was evident at all locations indicating a whole-body resonance in this frequency range. Txy peak was smallest at T8 and greatest at the head with medians of 0.15 and 0.46, respectively. Txx peak was smallest at L4 and greatest at the head with medians of 0.65 and 2, respectively. Txz peak was smallest at T8 and greatest at the head with medians of 0.58 and 1.3, respectively. At T12 and L4 and at frequencies below 4 Hz, Txz was as high as or higher than Txx. At low frequencies, Txx decreased with moving down the spine while an opposite trend was found at high frequencies. Txz decreased with moving up the spine from L4 to T8. Txz at T1, however, was higher than that at T8, possibly influenced by the high motion of the head. The results are useful for developing models that help better understanding of human response to horizontal vibration.

Power Absorbed by the Standing Human Body During Whole-Body Vibration Training

Absorbed power (AP) is a biodynamic response that is directly related to the magnitude and duration of vibration. No work has previously investigated the power absorbed by the standing human body during the exposure to vibration training conditions or otherwise. This article reports the power absorbed by the standing human body under whole-body vibration (WBV) training conditions. In this work, the force and acceleration used to calculate the apparent mass by Nawayseh and Hamdan (2019, "Apparent Mass of the Standing Human Body When Using a Whole-Body Vibration Training Machine: Effect of Knee Angle and Input Frequency," J. Biomech., 82, pp. 291-298) were reanalyzed to obtain the AP. The reported acceleration was integrated to obtain the velocity needed to calculate the AP. The effects of bending the knees (knee angles of 180 deg, 165 deg, 150 deg, and 135 deg) and vibration frequency (17-42 Hz) on the power absorbed by 12 standing subjects were investigated. Due to the different vibration magnitudes at different frequencies, the AP was normalized by dividing it by the power spectral density (PSD) of the input acceleration to obtain the normalized AP (NAP). The results showed a dependency of the data on the input frequency as well as the knee angle. A peak in the data was observed between 20 and 24 Hz. Below and above the peak, the AP and NAP tend to increase with more bending of the knees indicating an increase in the damping of the system. This may indicate the need for an optimal knee angle during WBV training to prevent possible injuries especially with prolonged exposure to vibration at high vibration intensities.

Modelling the apparent mass of the standing human body under whole-body vibration training conditions

Several studies have measured the vibration transmitted to and through the human body under vibration training conditions. However, no work has modelled the apparent mass of the human body under such conditions. In this work, a 2 degree-of-freedom model has been developed to predict the apparent mass of the standing human body under whole-body vibration training conditions. The parameters of the model were optimised using measured apparent mass of 12 subjects standing with different knee angle of 180°, 165°, 150° and 135°. Good agreement was found between the predicted and measured apparent mass with errors less than 3 kg in the median apparent mass magnitude and errors less than 6° in the apparent mass phase angle. The medians of the optimised parameters of the 12 individual apparent masses were close to the corresponding optimised parameters of the median apparent mass of the 12 subjects. Compared to standing with extended legs, bending the knees was found to affect mainly the parameters (i.e. stiffness and damping) of the model close to the source of vibration. Bending the knees decreased the mass of the model close to the source of vibration and increased the mass away from the source of vibration. Among the postures with bent knees, the change in the model parameters was generally not significant. The model can be used as a tool by manufacturers of whole-body vibration training machines to test the performance of the machines during the design stage and/or after production. This will decrease the number of experimentations with human subjects which guarantees consistency, repeatability, time-saving and safety.

Effect of gender on the biodynamic responses to vibration induced by a whole-body vibration training machine

Whole-body vibration training machines are used by both male and female users. However, studies investigating the biodynamic responses to vibration during training have used either mixed-gender subjects or male subjects. No study has investigated the effect of gender on the biodynamic responses under vibration training conditions. The objective of this study is to investigate the effect of gender on the apparent mass and the vibration of the head of standing people during exposure to vibration. A total of 40 subjects (20 females and 20 males) were exposed to vertical vibration at six frequencies in the range 20-45 Hz and vibration acceleration in the range 10.8-20.9 m/s² (peak). The subjects stood on a force platform mounted on the vibrating plate of the machine adopting an upright standing posture with their knees unlocked and their arms straight along their bodies. The vertical acceleration and force at the interface between the vibrating plate and the feet were measured and used to calculate the apparent mass. The accelerations of the head in the x-, y- and z-directions were also measured and used to calculate the transmissibility to the head. The apparent mass of males was found higher than that of females. The transmissibility to the head in all directions was found higher in females than males. The differences in the biodynamic responses between males and females were attributed to the differences in body properties and structure of the two genders. The results of this study imply the need for gender-specific vibration training programmes.

Relevance of Whole-Body Vibration Exercises on Muscle Strength/Power and Bone of Elderly Individuals

Beneficial effects are associated with whole-body vibration exercises (WBVEs). Increases in muscular strength/power, flexibility, and gait speed; improvements in bone mineral density, balance, and the quality of life; and decreased pain and risk of falls are reported. The aim is to present a review about the importance of WBVE for elderly individuals, considering clinical studies and meta-analyses, on bone and muscle strength/power. There is evidence supporting beneficial effect of WBVE in postmenopausal women (PW); however, effects in PW with osteoporosis are unclear. Age-related decrease in muscle mass and function contribute to undesirable health conditions, including death risk. The WBVEs improve muscle strength/power, functional independence measure, balance, and various fall risk factors, and mobility, measured by Timed Up and Go test, increased significantly after WBVE. An explanation for the absence of positive effects in some outcomes could be related to discrepancies in WBVE protocols as well as the populations tested. It is concluded that WBVE is effective for counteracting the loss of muscle strength associated with sarcopenia in elderly individuals. Balance and leg and plantar flexor strength improvements due to WBV indicate benefit to reduce risk and incidence of falls, frailty, and fracture risks. However, long-term feasibility of WBVE for musculoskeletal and bone health in elderly individuals needs further investigation.