Vibration good for reliving back pain
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By Kim Sang-hyuk
We live in a world with numerous slight vibrations.
We feel vibration while commuting on the bus or in a car and experience a huge increase in vibration when we pass over a speed bump.
Our cellular phone vibrates in our pockets or on our desks, and our body even feels vibration going up and down the stairs.
As sound waves carry unique oscillation frequencies, vibration allows us to hear various sound sources and even allows us to relax in a massage chair or on physical therapy equipment.
As previously mentioned, vibration greatly affects our lives positively, but for our spines, it is not always beneficial. In fact, vibration might be the cause of some spine diseases.
Types of job that generally bring about spine diseases include work that requires heavy physical efforts; lifting and forceful movements; bending, twisting, or awkward posture; whole body vibration; and static work posture.
Many publications describe the correlation between the work environment involving vibrations and the degeneration of the spine; most refer to a commuting medium, such as a tractor, truck, bus, helicopter, and heavy equipment.
However, not all vibrations affect the spine negatively. As our body is composed of different materials and tissues, each part is affected differently by different vibrations.
Some body parts react to resonant frequencies like a tuning fork. A study by Grandjean and Guo indicated that the resonant frequency of the spine is 3 to 8 Hz, and the vertebrae and discs feel a greater impact between these ranges.
In the case of the cervical spine, the resonant frequency is 3 to 4 Hz.
Then, aside from frequency, are there any differences in the forces affecting our bodies from the workplace or vehicle type?
The answer is yes.
When testing a vehicle, research usually includes vibration frequency.
The calculation of the forces involves mass and velocity, where the mass can differ and the vibration frequency can differ depending on the type of vehicle.
Exact velocity might be different, but typical vehicle reaches a velocity of 0.4m/sec2 (bus = 0.6m/sec2; tractor = 0.82m/sec2; and tank or military vehicle = 2.5 to 2.6m/sec2). A typical automobile affects the spine greatly, but a bus or tractor generates a greater vibration, thereby affecting the spine more.
In addition to the vibration frequency, another important factor is total vibration dose.
In other words, the total time exposed to the vibration is important.
Depending on how long we expose our bodies to vibration, the effect on the progression of disc herniation differs.
How can we minimize the effect on the spine from vibration?
First, it is important to drive along as smooth a road as possible; if we cannot change the type of vehicle we are driving, it is important to carefully choose an even road.
Second, air suspension seats are better than mechanical suspension seats.
According to a study by Motmans on forklift drivers, air suspension seats absorbed about 22 to 29 percent of the impact.
Third, as the speed of the vehicle increases, there is a greater chance of entering the resonant frequency range; thus, driving slowly or maintaining the right speed is important.
Finally, a body needs rest after a certain amount of impact.
In between work, stretching or taking a quick rest will greatly help our exhausted spines.
The writer is director of the spine center at Bumin Hospital Seoul in Gangseo District. He was named in the 2015 edition of Marquis Who's Who.