Whole body vibration is a generic term used when vibrations (mechanical oscillations) of any frequency are transferred to the human body. Humans are exposed to vibration through a contact surface that is in a mechanical vibrating state. Humans are generally exposed to many different forms of vibration in their daily lives. This could be through a driver's seat, a moving train platform, a power tool, a training platform, or any one of countless other devices. [1] It is a potential form of occupational hazard, particularly after years of exposure.
When high frequency vibrations [2] (above 50 Hz) enter through the hands, occupational safety concerns may arise. For example, working with a jackhammer has been known to develop vibration white finger. Exposures and limits have been estimated in the ISO 5349-1 for hand-transmitted vibration. [3]
Whole body vibration training as a form of physical exercise can offer some fitness and health benefits, but it is not clear if it is as beneficial as regular physical exercise. [4] A 2018 meta-analysis showed that whole body vibration can improve bone mineral density in the lumbar spine of postmenopausal women as well as the femoral neck density of postmenopausal women younger than 65. [5]
Humans are sensitive to mechanical oscillations ranging in frequency from well below 1 Hz up to 100 kHz. [6] Lower frequencies of vibration lead to human motion sickness [7] while higher frequencies can lead to general annoyance and discomfort. The minimization of discomfort due to vehicle vibration is important in the automotive industry where ride quality is important. Discomfort and even pain may be extremely prevalent in situations where medically injured patients are transported. The discomfort due to vibration can be estimated in various environments. [8] [9]
Workplace exposures to whole-body vibrations for long durations can lead to musculoskeletal problems of many kinds. [10] Problems of the neck and lower back in particular can be common for operators of heavy equipment including construction, forestry, agriculture, and trucking. Other occupations where whole-body vibrations may be present include aircraft operators, sea vessel workers, drivers of public transportation like trains and buses.
Farmers with long-term exposure to whole body vibration and mechanical shocks have a higher prevalence of back pain (compared to those not exposed to vibration), and the prevalence increases with vibration dose. [11] Long-term exposure affecting the whole body leads to spinal degeneration (spondylosis) and increased risk of low back pain. [12] [13]
Factors that affect the occupational exposure to whole-body vibration include the frequency of vibrations, the magnitude of vibrations, the daily exposure to vibrations, the standing or seating posture of the operator, the direction of the vibration, and how tightly coupled the human is to the source of the vibration. [14] Exposure limits and estimates have been characterized in the ISO 2631-1 [15] for whole-body vibration. Measurements of vibration exposure are usually taken at the human/vibration interface.
Injured patients can be exposed to shocks and vibrations during transport which can worsen patient conditions due to involuntary motions of the body. Many forms of immobilization devices are used to limit this motion with varying degrees of success. [16] [17] [18] Common modes of patient transport include hand carried stretcher (litter), ground ambulance, and air medical services which all contain multiple forms of shocks and whole-body vibrations.
Measurements are taken with accelerometers to estimate the amount of vibration exposure to the human body. These measurements are taken at the human body or at the vibration source or surface. [14] Measurements of different directions are taken to relate the motion direction with the response of the human body. [19] Specifically, transfer functions can be used to determine the human response to the vibration. [20] Measurement techniques for estimating exposures to whole body vibrations and hand-arm vibration have been developed in International Standards. [21] [3]
Vibration training is the deliberate exposure to the body of varying frequencies/amplitudes/forces using certain joint angles for any limited time (approximately 1 minute sets). It is also known as vibration therapy, vibrotherapy, biomechanical stimulation, mechanostimulation and biomechanical oscillation. It employs low amplitude, low frequency mechanical stimulation. It can be pivotal/oscillating (vibrating from side to side) or lineal (vibrating up and down).
The immediate predecessor of modern vibration training is Rhythmic Neuromuscular Stimulation (RNS). In then East Germany, Biermann was experimenting with the use of cyclic massage and its effects on trunk flexion as early as the 1960s. [22]
The technique has been tested on turkeys in the hope of finding a benefit that could be used for astronauts. [23] Engineering issues came into play when an attempt was made to upgrade the test machine to support the weight of a human being. Once the vibration intensity grew strong enough to lift over 40 kg, fractures appeared in the steel. The first bed-rest study using a vibration training device for humans was done by the European Space Agency (ESA) in 2003 in Berlin [24] (Berlin Bedrest Study, BBR). The same technology was then used in several parabolic flight campaigns of the DLR (German Aerospace Agency) starting in 2006 where the feasibility of use of a lightweight vibration training device under microgravity conditions was demonstrated and in 2009 and 2010 where basic research on influence of microgravity on vibration training effects was investigated. [25] [26]
Since 1961, NASA has been testing adding light vibrations to exercise equipment and systems to minimize vibration transmission of existing exercise devices to the space station, like the Treadmill Vibration Isolation System (TVIS) and the Cycle Ergometer Vibration Isolation System (CEVIS). Companies referencing NASA directly in their marketing campaigns in relation to vibration training for muscular activity may be misleading.[ citation needed ]
The first Galileo machine patent was filed in 1996 in the same year the first Galileo device was commercially available. [27] [28] In 1996, the first Galileo vibrating dumbbell patent was filed. [29]
A 2018 meta-analysis concluded that whole body vibration improved lumbar spine bone mineral density (BMD) in postmenopausal women, and enhanced femoral neck BMD in postmenopausal women younger than 65 years. [5]
A review in 2014 concluded that there is little and inconsistent evidence that acute or chronic whole body vibration could improve the performance of competitive or elite athletes. [30]
Cochrane reviews have concluded that there is insufficient evidence of effect of whole body vibration training on functional performance of people with neurodegenerative disease, [31] or in disease-related problems in people with fibromyalgia. [32]
Some research supports benefits for arthritis [33] and knee pain. [33]
Vibrating platforms fall into different, distinct categories. The type of platform used is a moderator of the effect and result of the training or therapy performed. [34] Main categories of machine types are:
Other machine types are low energy/low amplitude lineal and low energy/high amplitude lineal.
Concerning the z-movements, two main types of system can be distinguished: [34] [35] [36]
Systems with side alternation usually have a larger amplitude of oscillation and a frequency range of about 5 Hz to 40 Hz. Linear/upright systems have lower amplitudes but higher frequencies in the range of 20 Hz to 50 Hz. Despite the larger amplitudes of side-alternating systems, the vibration (acceleration) transmitted to the head is significantly smaller than in non-side-alternating systems [37] while at the same time muscle activation even at identical vibration parameters are increased in pivotal systems. [38] However, standing with both heels on one side of a side-alternating machine facing side-ways results in significant acceleration transmitted to the head and center of gravity of the upper body. At least one such whole body vibration owner's manual suggest this variation calling it "Stand-a-side Pose". At the outer edge of the plate the amplitude is typically about 10 mm, which is more than the 3 mm maximum of a linear vibrator and not practical. The amplitude and impact can be reduced by centering, e.g., a gardener's knee pad, ~ 16"x 8" x 3/4", on the plate and standing with the heels toward the outer edge of the pad. While this is useful it does not replace a machine whose entire plate moves up and down in a linear fashion allowing for a variety of positions and activities.
Mechanical stimulation generates acceleration forces acting on the body. These forces cause the muscles to lengthen, and this signal is received by the muscle spindle, a small organ in the muscle. This spindle transmits the signal through the central nervous system to the muscles involved. [37] [39]
Power Plate is a brand of vibrating platform consisting of a vibrating base, which may vibrate up and down approximately 1 to 2 millimetres (39 to 79 thou) (1/16") 25 to 50 times per second. [40] The machine is large enough to accommodate a person in deep squat. Traditional exercises such as squats and push-ups can be done on the vibrating base. [41]
LifetimeVibe is a brand of vibration machine with a platform and a vertical column with handles and controls at arm-level. This machine registers 42 decibels of sound, about as quiet as a human whisper. Made in the USA of cherry wood and power coated steel, it simulates a walking motion, using see-saw oscillations from 0-10mm, with a frequency of 0 to 15.5 Hz. Simple controls are mounted on a vertical column with 12 different programs and a manual mode with a rotating knob to adjust frequency.
Rather than accelerating instantly with a jolt to the body, this machine starts and stops gradually to adjust to the chosen frequency. This smooth motion feels comfortable and natural, like walking, and is especially helpful for seniors and for those with health challenges. Athletes and people of all ages also use the machine for athletic performance, recovery and muscle and joint strength. [42]
Galileo (in the US up until 2014 also available as Vibraflex) is a brand of vibration training platforms used as exercise equipment as well as for therapeutic use. It consists of a vibration platform which vibrates sinusoidal side alternating like a see-saw. Depending on the device size it oscillates with an amplitude of up to 6 mm (equivalent to a peak to peak distance of 12 mm) and a frequency of 5 Hz to 40 Hz (5 to 40 repetitions per second). Galileo is manufactured in Germany by the German company Novotec Medical GmbH. Since 2004 Galileo is also available as a medical device.
The base plate of Galileo vibration training devices is moving like a see-saw. This side alternating motion is supposed to mimic human gait in order to utilize nearly physiological motion patterns close to the side alternating human gait. The side alternation causes the hip to tilt which requires the contra lateral muscles of the back to be activated – while one leg is lifted the other drops. [43] Compared to vertically vibrating devices the side alternating motion results in very low acceleration acting on the centre of gravity of the upper body and the head. [44] [37] [45] But see the Stand-a-side Pose described above which does result in significant acceleration.
Juvent's Micro-Impact Platform is a platform in the low magnitude mechanical stimulation category. It uses energy levels less than 1g (0.3g - 0.4g) and operates in a safe range of frequency between 32 Hz - 37 Hz. It also moves the user only 0.05mm in the Z-axis. The platform uses resonance to gain efficient transmission of energy through the user. It meets or exceeds ISO (Int'l Organization for Standardization) and OSHA (Occupational Safety and Health Administration) standards for human exposure to vibration. It has been used in numerous clinical trials (VIBE Study, St.Jude Hospital for Children) and is registered with the FDA.
A vibrating belt machine (also Mueller belt machine, belt massager, or jiggler machine) is an exercise machine that uses a vibrating belt, to be used around the waist or buttocks.
Ultrasound is sound with frequencies greater than 20 kilohertz. This frequency is the approximate upper audible limit of human hearing in healthy young adults. The physical principles of acoustic waves apply to any frequency range, including ultrasound. Ultrasonic devices operate with frequencies from 20 kHz up to several gigahertz.
The acoustic reflex is an involuntary muscle contraction that occurs in the middle ear in response to loud sound stimuli or when the person starts to vocalize.
An electric toothbrush is a toothbrush that makes rapid automatic bristle motions, either back-and-forth oscillation or rotation-oscillation, in order to clean teeth. Motions at sonic speeds or below are made by a motor. In the case of ultrasonic toothbrushes, ultrasonic motions are produced by a piezoelectric crystal. A modern electric toothbrush is usually powered by a rechargeable battery charged through inductive charging when the brush sits in the charging base between uses.
The brown note, also sometimes called the brown frequency or brown noise, is a hypothetical infrasonic frequency capable of causing fecal incontinence by creating acoustic resonance in the human bowel. The name is a metonym for the common color of human faeces. Attempts to demonstrate the existence of a "brown note" using sound waves transmitted through the air have failed.
Vibration white finger (VWF), also known as hand-arm vibration syndrome (HAVS) or dead finger, is a secondary form of Raynaud's syndrome, an industrial injury triggered by continuous use of vibrating hand-held machinery. Use of the term vibration white finger has generally been superseded in professional usage by broader concept of HAVS, although it is still used by the general public. The symptoms of vibration white finger are the vascular component of HAVS.
The tensor tympani is a muscle within the middle ear, located in the bony canal above the bony part of the auditory tube, and connects to the malleus bone. Its role is to dampen loud sounds, such as those produced from chewing, shouting, or thunder. Because its reaction time is not fast enough, the muscle cannot protect against hearing damage caused by sudden loud sounds, like explosions or gunshots.
High-frequency ventilation is a type of mechanical ventilation which utilizes a respiratory rate greater than four times the normal value. and very small tidal volumes. High frequency ventilation is thought to reduce ventilator-associated lung injury (VALI), especially in the context of ARDS and acute lung injury. This is commonly referred to as lung protective ventilation. There are different types of high-frequency ventilation. Each type has its own unique advantages and disadvantages. The types of HFV are characterized by the delivery system and the type of exhalation phase.
Musculoskeletal disorders (MSDs) are injuries or pain in the human musculoskeletal system, including the joints, ligaments, muscles, nerves, tendons, and structures that support limbs, neck and back. MSDs can arise from a sudden exertion, or they can arise from making the same motions repeatedly repetitive strain, or from repeated exposure to force, vibration, or awkward posture. Injuries and pain in the musculoskeletal system caused by acute traumatic events like a car accident or fall are not considered musculoskeletal disorders. MSDs can affect many different parts of the body including upper and lower back, neck, shoulders and extremities. Examples of MSDs include carpal tunnel syndrome, epicondylitis, tendinitis, back pain, tension neck syndrome, and hand-arm vibration syndrome.
Phonomyography (PMG) is a technique to measure the force of muscle contraction by recording the low frequency sounds created during muscular activity.
Shock pulse method (SPM) is a technique for using signals from rotating rolling bearings as the basis for efficient condition monitoring of machines. From the innovation of the method in 1969 it has been further developed and broadened and is a worldwide accepted philosophy for condition monitoring of rolling bearings and machine maintenance.
The Mechanostat is a term describing the way in which mechanical loading influences bone structure by changing the mass and architecture to provide a structure that resists habitual loads with an economical amount of material. As changes in the skeleton are accomplished by the processes of formation and resorption, the mechanostat models the effect of influences on the skeleton by those processes, through their effector cells, osteocytes, osteoblasts, and osteoclasts. The term was invented by Harold Frost: an orthopaedic surgeon and researcher described extensively in articles referring to Frost and Webster Jee's Utah Paradigm of Skeletal Physiology in the 1960s. The Mechanostat is often defined as a practical description of Wolff's law described by Julius Wolff (1836–1902), but this is not completely accurate. Wolff wrote his treatises on bone after images of bone sections were described by Culmann and von Meyer, who suggested that the arrangement of the struts (trabeculae) at the ends of the bones were aligned with the stresses experienced by the bone. It has since been established that the static methods used for those calculations of lines of stress were inappropriate for work on what were, in effect, curved beams, a finding described by Lance Lanyon, a leading researcher in the area as "a triumph of a good idea over mathematics." While Wolff pulled together the work of Culmann and von Meyer, it was the French scientist Roux, who first used the term "functional adaptation" to describe the way that the skeleton optimized itself for its function, though Wolff is credited by many for that.
Mechanography is a medical diagnostic measurement method for motion analysis and assessment of muscle function and muscle power by means of physical parameters. The method is based on measuring the variation of the ground reaction forces over the time for motion patterns close to typical every day movements. From these ground reaction forces centre of gravity related physical parameters like relative maximum forces, velocity, power output, kinetic energy, potential energy, height of jump or whole body stiffness are calculated. If the ground reaction forces are measured separately for left and right leg in addition body imbalances during the motions can be analysed. This enables for example to document the results of therapy. The same methodology can also be used for gait analysis or for analysis of stair climbing, grip strength and Posturography. Due to the utilization of every-day movements reproducibility is high over a wide age range
Speech science refers to the study of production, transmission and perception of speech. Speech science involves anatomy, in particular the anatomy of the oro-facial region and neuroanatomy, physiology, and acoustics.
In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the reception of such waves and their perception by the brain. Only acoustic waves that have frequencies lying between about 20 Hz and 20 kHz, the audio frequency range, elicit an auditory percept in humans. In air at atmospheric pressure, these represent sound waves with wavelengths of 17 meters (56 ft) to 1.7 centimeters (0.67 in). Sound waves above 20 kHz are known as ultrasound and are not audible to humans. Sound waves below 20 Hz are known as infrasound. Different animal species have varying hearing ranges.
Vibration is a mechanical phenomenon whereby oscillations occur about an equilibrium point. The word comes from Latin vibrationem. The oscillations may be periodic, such as the motion of a pendulum—or random, such as the movement of a tire on a gravel road.
Hearing, or auditory perception, is the ability to perceive sounds through an organ, such as an ear, by detecting vibrations as periodic changes in the pressure of a surrounding medium. The academic field concerned with hearing is auditory science.
Ergonomic hazards are physical conditions that may pose a risk of injury to the musculoskeletal system due to poor ergonomics. These hazards include awkward or static postures, high forces, repetitive motion, or short intervals between activities. The risk of injury is often magnified when multiple factors are present.
Locomotion in space includes all actions or methods used to move one's body in microgravity conditions through the outer space environment. Locomotion in these conditions is different from locomotion in a gravitational field. There are many factors that contribute to these differences, and they are crucial when researching long-term survival of humans in space.
Vibration welding refers to a process in which two workpieces are brought in contact under pressure, and a reciprocating motion (vibration) is applied along the common interface in order to generate heat. The resulting heat melts the workpieces, and they become welded when the vibration stops and the interface cools. Most machinery operates at 120 Hz, although equipment is available that runs between 100–240 Hz. Vibration can be achieved either through linear vibration welding, which uses a one dimensional back and forth motion, or orbital vibration welding which moves the pieces in small orbits relative to each other. Linear vibration welding is more common due to simpler and relatively cheaper machinery required.
Vibroacoustic therapy (VAT) is a type of sound therapy that involves passing low frequency sine wave vibrations into the body via a device with embedded speakers. This therapy was developed in Norway by Olav Skille in the 1980s. The Food and Drug Administration determined that vibroacoustic devices, such as the Next Wave® PhysioAcoustic therapeutic vibrator, are "substantially equivalent" to other therapeutic vibrators, which are "intended for various uses, such as relaxing muscles and relieving minor aches and pains"; thus, vibroacoustic devices are "exempt from clinical investigations, Good Guidance Practices (GGPs), and premarket notification and approval procedures."