Is it true that Power-Plate can decrease calcium levels? If so, would you advise a limitation of any kind when working with older (60+) clients who have had a history of severe leg breaks?
This is a very interesting question. The notion that acceleration (vibration) training could lead to decreased calcium levels could easily be answered with a definitive “no” if one simply looks at outcomes in isolation. By this I mean that if one looks at the function of calcium on human form and function, and thus its subsequent impact on outcomes, there is no literary basis to think that this could occur. I for one have seen no research (academic or clinical) or practice based evidence to suggest this. In fact, we see great evidence that the opposite may indeed be more likely, which is an increase in calcium levels and utilization.
If we delve into the many and complex functions of calcium, we rapidly learn it is a crucial mineral to optimizing human performance and life quality. For our purpose here, we will look at just two of its main functions: muscle function and bone function.
We are well aware that bone dynamics is a continual tearing down (re-absorption) and building (formation) of bone matrix. There are three types of cells involved in this dynamic: Osteocytes, Osteoclasts and Osteoblasts. Think of these as the detectors, re-absorbers and builders respectively. Osteocytes detect mechanical strain on bone, and the signals are either piezoelectric (through ionic currents detecting blood flow in the tunnels of the matrix) or from bone deformation. The result is that they in turn send signals to stimulate bone re-absorption or formation.
Osteoclasts are charged with bone re-absorption, by dissolving its calcium and phosphorous and releasing it into the bloodstream. Osteoclasts create an acidic micro-environment necessary to dissolve old bone minerals and activate required enzymes for re-absorption. Osteoblasts are the builders that function to form and deposit new bone matrix. The delicate balance between these last two cells is crucial to bone development. If osteoclastic activity exceeds osteoblastic activity, then a net loss occurs.
If you re-read the first line of the last paragraph, you will see a most interesting thing. All exercise will deplete calcium! It is the role of the Osteoclasts to break down and dissolve calcium. Without this, new bone cannot be formed. One must tear down the old foundation before one can build a new house. It is only when the imbalance occurs and the break down exceeds formation that we have a problem. Much of this is a natural consequence of poor lifestyle with ageing, but we should never forget that this is a process that we desire through exercise (i.e., to stress the system in order to induce adaptation, or the over load principle). Thus, we must look for a certain amount of calcium loss before we can induce an anabolic response.
So how do we know whether we are in a healthy balance? This is where we (as health practitioners) can only look at outcomes. If there is a consistent and progressive loss of bone mineral density (outcome), we can give a pretty good guess at the mechanisms (re-absorption versus formation). A quick look at some interesting peer reviewed research shows, repeatedly, that mechanical vibration is an exciting, safe and effective option for fighting bones loss. With studies in post menopausal women showing statistical improvements (up to 1.5 percent) at hip and knee, one can assume a positive calcium balance. Otherwise bone formation would not likely exceed re-absorption. Another way of stating this is that there are positive calcium depletion levels (osteoclastic activity)! So yes, it is depleted, and we want it to be.
So now let’s look at the second function: muscle function. Acceleration training has been well researched in neuromuscular responses, particularly looking at strength (both static and dynamic) and power as well as postural sway, balance and reaction. Regardless of its outcomes, what we are really talking about here is the body’s ability (CNS + Kinetic Chain) to absorb, transform and produce force, or if you prefer, the loading, transformation and unloading of forces. It is simply the application of this force that determines its nature (i.e., power versus stability versus strength, etc). We cannot separate them from each other completely and must recognize that each will inherently influence the foundation of the other. But no matter how you slice it, we are discussing force.
Acceleration training uses the parameters of frequency and amplitude to create magnitude. Magnitude can be viewed as the load or forces being produced by a vibration platform due to its rate change of speed (acceleration) expressed in g-forces. Therefore, we are not only concerned with how fast we are asking the CNS to work (frequency), but we also ask, “How much force can the tissues tolerate (magnitude)?” Most people are getting caught up in the first part of the equation, and virtually no one is considering the second. We know there is a range between 25 and 40 Hz that is most safe and effective, but this could vary between 1 and 15 gs, depending on the amplitude it is interacting with!
For the muscles to contract at a relative speed (frequency) as well as actively load, transform and unload forces, there has to be sustained action potential. Muscle Physiology 101 tells us that upon contraction of a muscle (unloading), there is a decreased action potential, and upon lengthening (deceleration or loading), there is an increased action potential. Vibration training, via the Tonic Vibration Reflex (TVR), has a positive impact on sustaining action potential. Indeed, it appears to increase firing rates and synchronization as well as enhance post activation potential. What this means is that vibration is not decreasing the muscles’ ability to contract at optimal force levels. Why is this important in answering your question?
Muscles cannot contract and action potential cannot be sustained without the continuous presence of… calcium! It would be physiologically impossible to sustain mechanical work/muscle action without the presence of calcium due to its significant role in the sliding filament theory of muscle action (cross bridge binding of actin and myosin demands calcium). Given the significant research findings in neuromuscular outcomes thus far, it would be hard to imagine a decrease in calcium levels being possible when work and performance are going up.
Finally, it is noteworthy that calcium levels and utilization in the body are inherently affected by the hormonal system. In particular, HGH has a huge role to play in the assimilation of calcium, in turn impacting on muscle contraction and rate of force production, among other things. A few studies in vibration have shown positive findings on increasing HGH, IGF-1 and Testosterone, while suppressing exercise increased response in cortisol. Ultimately, this is creating an anabolic environment for positive change and would definitely affect calcium function in the body. This would also help to explain why the bone mineral studies are showing such positive findings. Post menopausal women do not have much HGH… or testosterone for that matter!
So I guess I would conclude by saying:
- No, vibration training does not deplete calcium levels in body as evidenced by both the outcomes proved thus far and a good understanding of exercise physiology.
- Yes, vibration training does deplete calcium levels in the body but in a positive way as to induce new bone formation… as does all good exercise.
The outcomes that would appear to validate this argument are:
- Increased bone mineral density
- Increased neuromuscular function and muscle action (strength, power, etc)
- Enhanced anabolic environment (HGH, Testosterone and IGF go up and cortisol goes down)
I hope this helps to shed some light on a very interesting question in a most confusing science.
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