There are few mechanisms that cause muscle growth or hypertrophy. In general, in order to increase or maintain muscle mass, load has to be applied in order to strain the muscle fibers.
The amount of load applied to the muscle must be greater than the muscle is accustomed to. For example, simple walking uses various leg muscles to move the body forward, but it would not cause muscle growth, mainly because the amount of force on each muscle is fairly low.
The principal mechanism of muscle growth is when muscles fibers are damaged due to excessive force, or contraction and the subsequent healing or fusing of the damaged muscle fibers. Note that muscles can only pull or contract.
Once it is healed it gets bigger and stronger. So, in short, for muscles to grow, one must exert heavier and heavier mechanical loads onto them.
So, the latex extension force matches quite nicely with the muscle’s ability. Free weights, on the other hand, exert a consistent force on the muscle. So, with latex tubes the user can select heavier loads knowing that the load is light at the beginning and gets heavier as the muscle contracts and becomes stronger. Moreover, it is nearly impossible to “cheat” or use momentum, like we all do at times with free weights. It is these sudden movements or “jerks” that cause nasty injuries at times, especially when lifting heavy loads. Latex resistance tubes reduce or eliminate the chance of these nasty injuries. Another advantage of the resistance tube is that you can push to your maximum or beyond without any fear of hurting yourself, or the need to have a “spotter”.
Furthermore, the length of these tubes is set to provide the desired force for most of the movement throughout the strength training.
The resistance tubes are color coded, so that one can select them according to the type of exercise to be performed.
It is very important to note that the amount of force required to extend these resistance tubes increases as the tube is extended further. So, in order to increase the desired load, tube(s) could be extended further by re-positioning yourself. For example, move your body or point of movement further away from where the tubes are located.
Since Pressbee is based on latex resistance tubes, and these tubes are to provide the range of loads for the users, they are considered the most important part of the equipment and must be the “best” available.In order to have consistent load throughout the life of the tubes and have the appropriate level of modulus of elasticity, or using a simpler term force vs extension, many different latex tubes from all over the world, including Brazil where the original Hevea Brasiliensis rubber trees were discovered, were acquired and tested. Some of the tubes tested in order to determine the most suitable ones for this application are shown below. Finally, it was a supplier in Ohio, USA that provided the latex tubes that met my expectations. Some of the test data obtained from the various tube sizes in order to verify the force vs extension considered to be satisfactory for this application are shown below. For a given latex tube size, one would expect the tube to provide the required load when it is extended by an arm-length or about two feet (60 CM). This is a typical extension or movement for most of our body parts – be it bicep curl, chest press or hamstring extension etc. To achieve the resistance load for this level of movement, a matrix of length and force was used to determine optimum length of the tubes, so that the load is not too light at the beginning of the movement and not too heavy at the end of movement. For example, long tubes would provide very light resistance at the beginning, conversely short tubes would provide a very heavy load at the end.