Nitrogen Gas Spring Resistance - What's the big deal? Strength training, resistance training, anaerobic training, etc., all have one thing in common, they all use high amounts of a resistant force, or load, for the muscles to contract against. Exercise in itself is merely inducing a physical stimulus that produces a physical adaption. If the resistance force is very strong the adaptation is likely strength. If the resistance force is low, we are able to do it more times and we don't get as strong, but we add an endurance adaptation feature. So, it can be said in relative terms and strong associations that the quality of the resistance force will determine the quality of the adaptation.
For the most part we think of this as weight training and the tools are weighted objects or machines that use weight as the resistance element. And thusly since weights obey certain physics characteristics they can have limitations in their qualities of adaptive features. If the weight is heavy, it is not likely it will be moving fast any time soon, and the adaptations will be reflected by those physics. Inertia, centrifugal, centripetal, and momentum forces accompany weights because of the density of the mass and when velocity is changed these forces start to inhibit objectives of training adaptation. Big weights do require high amounts of muscle recruitment and that is for the most part what we are looking to adapt. With every bit of great things weights provide they also have downsides that often get over looked. Adaptive slow movement patterns and delayed onset of muscle soreness (DOMS) are things that hardly get attention.
Other modalities have come about as a result of looking into weights having some limitations. Resistance can come from many devices and forms. Bows, elastomer bands, mechanical springs, and other fluid hydraulic systems have had some success at overcoming the limitations of weights. Air pressure and now nitrogen gas pressure has been used. Some of these are great because they are very inexpensive and convenient, others like bows are better because they have other features. What makes nitrogen gas springs great will be of discussion and why they may be the best form of resistance for training adaptations. Inexpensive and tunable usually isn't something resistance has. N-gas could be the high performance resistance we all are looking for.
In contrast to most other types of springs, n-gas springs have a built-in pre-tension force and a flat spring characteristic. This means that there is only a small difference in force between full extension and full compression and when you are doing a repetition the force tends to stay fairly constant. The fairly constant part is probably the most intriguing aspect and this part will be of interest later in the article.
Looking at those force/stroke characteristics of the different springs, the gas spring tends to increase slightly during compression stroke whereas the others tend to increase quite aggressively. This is a big deal when trying to perform a repetition such as a curl. With disc, coil, or rubber springs, there is very little force at the beginning, and you would start flexion of the elbow via a biceps/brachialis contraction and find that within a few degrees that the resistance is adequate for an intense muscular contraction. However a few degrees more, the resistance cannot be over come as it is too great. So a full range of motion (ROM) for the curl is not obtainable with these resistance devices unless used on a machine that could change this aggressive stroke/force increase. The gas spring can be tuned with rod diameter and tube volume to make this stroke/force what you want.
Now, the BIG secret that only few know about gas springs and REALLY why they are better. In the graph you are looking at the compression force stroke and this is correlating to a concentric muscular contraction. What is happening on the eccentric side of the stroke force? With the disc, coil, and rubber springs they are reversed and pretty much the same. Having almost no mass to stabilize the velocity and aggressive stroke/force characteristics the disc, coil, and rubber tend to exhibit a shaky, spastic, vibration like feel. The opposite of weights. The bigger the weight the more stable it feels. With the disc, coil, or rubber, the higher the resistance the higher the spasticity or out of control feeling. Pull a an arrow back with a bow and hold it with 40 lbs of draw for a few seconds. You will feel this shake as the muscles lose contraction coordination from fatigue.
The N-gas spring does not do this. Why? Like a shock absorber, it has a piston pack inside to control these high velocity-low mass characteristics. This piston pack controls the movement speed and can be tuned as well in either direction. You can make it compress/extend fast and/or compress/extend slow. Depending on the piston pack dampening design the N-gas spring can do what ever you want. What do you want your resistance characteristics to induce? Can't do that with the others, even weights. Controlled feeling with velocity? The N-gas spring is the perfect choice. Stability of weights, velocity of springs. This is opening a whole new shift in training protocols since weights and reps are usually linked by velocity. The Strength/speed continuum established this. Now High Velocity/High Resistance (HVHR) is changing the rules and the adaptations.
The other big secret is that the N-gas spring does not have equal compression and extension forces because of the seal drag around the shaft. As you can see below that when a gas spring is compressing it has more force and when extending it has less. This would correlate to more concentric contraction force of the muscles during compression phase of the gas spring and less eccentric contraction phase force during gas spring extension. So what is the big deal and why is this important?
The big deal is that no matter what the velocity or speed of this extension or compression it is always the same force with the N-gas spring. With weights, a high velocity contraction would create a big increase in force because of the inertia induced, and less at the end because of momentum has been created. You can actually produce so much inertia at the beginning of an exercise with a weight that is actually has no force at all towards the end and it 'floats at the top. Sounds like fun until you realize that what goes up, must come down and when a high speed weight is decelerated coming back down it reeks havoc on the muscular structures and creates DOMS. Since this effect is reduced with the gas spring, DOMS is reduced by both effects of design. N-gas springs have almost zero mass, so inertia, momentum, and other forces are pretty much eliminated so there won't be any spiking forces that create injury. It is widely known that eccentric contractions cause DOMS and the N-gas spring has less because of seal drag and no momentum. Understanding this phenomenon of the gas spring and comparing it with others it is looking pretty attractive isn't it? But DOMS is GOOD right? You need muscle soreness to build more muscle, right? Gotta tear it down to build it up right? IS that right? Dogma and broscience is breathing its last breaths and the latest research shows no correlation. That's right. Being sore doesn't mean you are getting bigger and stronger.
However, that isn't the best part of the story with N-gas springs. It gets better. In the next article we will see how that there isn't just a protective or safety feature of N-gas springs for training applications. The N-gas spring just blew a big hole in the no pain-no gain philosophy of resistance training and while the curtain is being pulled back, we will see that N-gas pressure resistance has amazing applications in sport specific training, life extension-youth regeneration, and fat burning.