The 4 main reasons for a drop in performance are....
(1) Incorrect/cheap motors.
(2) Incorrect materials used in manufacturing of product.
(4) Just plain cheap everything
What are the concerns?
Safety and results....
All companies promote their own theory on what Fqs are more comfortable,safe and effective. Some vary wildly into the unknown, other take a more standard approach and have only a small range of options on their machines. But one thing the industry does have in common is ALL programs from ALL companies are based on the particular Fq the manufacturer that sold you the machine wants you to use.
What if the unit is not doing that actual Fq/speed?
This has been documented in the worlds largest selling unit, with variations of + or - 23% from the figure displayed on the control panel. And that was unloaded ( no-one on it ). When someone actually gets on the machine it will vary even more wildly depending on the persons weight and position on the machine. The same above unit was independently tested at universities in N.Z. and Australia , and was shown to drop almost all performance at only 80kg.
Note: This was not a cheap product at ( $18,000 N.Z. ) and should be a good indication that the price paid for a unit is not always an indication of quality.
Now not withstanding the safety issue ,this is really a problem for businesses looking for a machine to earn revenue off. The drop in performance is a very good indication that the units are indeed not of commercial quality. Some of the machines I have inspected being sold to businesses are the equivalent of large disposable razors. The limited lifespan directed at gaining future sales from you when they release a "new model" every 3 yrs or so. So not only does your customer not get what they paid for due to lack of performance in your machinery , you will also pay at some stage again to fix/upgrade or totally replace just to stay in business.
This is a simple one that anyone who has trained with any goal in mind will understand straight away.
How do you start a program if you do not know where that starting point is ?
I will use an engineering term here called the " Theoretical" . This is a base line that never changes from which to work with as a starting point for everything.
Eg.. If you are learning to run 8 miles , the 8 mile distance will never change but your time will.
Or... If you are lifting a 100Kg bench press , the 100kg will not vary but your reps will.
So in these instances your Theoretical is distance or weight.
In Vibration training platforms Fq/speed is one of the Theoretical you use to follow a program (there are others but this one is the simplest to measure).
If your theoretical was to change without your knowledge your results would become random and with little meaning. Now imagine trying to develop a program not having a stable theoretical to work with ?
Now the reason I have used the term "Theoretical" is this is the language used by engineers to allow them to test the performance of machines. A near perfect machine will follow the "theoretical line" on a graph as closely as is possible. Anything too far off will not pass. They use this system to test your car for road safety , ( Eg.. steering , brakes etc..) anything too far off the line and it is not road worthy . You fail.
For a trainer to effectively produce a Vibration Training program they will need to be first assured the machinery they are working with follows a straight theoretical line in tests. This will at least allow for some form of safety and progress to be maintained and recorded.
Any health or fitness professional serious about purchasing/using a Vibration Training platform should request engineering reports done ( loaded with varying weight and unloaded ). This will not cost much compared to buying a unit then finding out you have been ripped off. ( details on how to do this cheaply will be posted under this article. )
This one is obvious and will not need further explanation. Imagine being put in the position of saying to a customer.
" I am sorry , you are too heavy to go on my weight-loss machine "
To even produce a unit with such limitations and the errors addressed above must bring into question the dedication and motives of those involved. I am hoping in the future the industry agrees to regulate itself with pass and fail % of available products.
But until then education is our best weapon.