Тяжелая для меня тема: я не специалист в этой терминологии, поэтому надо внимательно меня вычитывать. Может быть много косяков по терминам
Day 83: Force vector
We do not know how good you are at physics but we hope that after today’s post you will change your attitude. If you look into any exercise you will see that they all are based on Newton’s mechanics! Only mechanics defines efficiency of exercises for different muscle groups not an opinion of a certain internet coach or an article in a glossy magazine.
This infopost uses information taken from the article of Dmitry Kalashnikov “Legends and myths of bodybuilding” since we do not have our own material on this topic yet.
First of all, we need to look into the words “muscle is loaded (stressed? worked?)”. It means that some homeostatic changes occured while it was doing mechanical work (because the muscle has to spend energy to do any work and this process produces free creatine, lactate, H+ ions). Workload tires the muscle and fatigue results in changes in adaptation. We are not interested to know if the muscle did any work. It is not enough to rely on our own feelings like “I feel how tense my muscle is, then I know it is working”. The muscle can be tense but it does not mean that it works against load. The muscle can be tense from other causes but we will talk about this later.
There is a question how do we know if the muscle is working against load? It is pretty simple. We know that work is being done against outer load. If we find the load and it is significant enough then we know that the muscle works against it. If we cannot find the source of the load then the muscle is not loaded, it has nothing to work against.
Taking into account that all movements of our joints are circular, the force that makes them rotate under liad is called torque and equals force multiplied by lever. The Lever is the shortest distance between centre of rotation to the point where the force is applied.
Let's look at the picture showing the bench press exercise with hands at shoulder width (narrow grip). The barbell is lowered below chest with elbows at the sides. We will see the following picture from behind and the side:
You see that the force that pushed the barbell goes through the elbow hence the lever equals zero and torque is zero as well. This force does not flex elbow therefore the tricep does no work. Tricep is shoulder extensor but there is no external force to flex the shoulder hence the tricep does not work. The elbow flexes as the shoulder extends and vice versa.
Naturally, there is some tension in the tricep to provide balance and correct trajectory for the barbell. This process is often mistakenly called stabilisation. Besides, muscles get tense involuntarily because the body tries to include as many muscles as possible to spread load between them. However this type of workload is negligble compared to working against considerable exterior force.
Can we change the technique to put more stress onto the tricep? Of course we can. We need to create torque that flexes the elbow then the tricep will work counteracting this force. We need to provide a lever. This is possible to achieve by lowering the barbell closer to the upper chest (making a hybrid with french press, fig. 4) or pointing elbows outwards (fig. 5).
It seems like the exercise practically did not change, we only changed slightly the position of hands but with this little change we were able to redistribute load and put more emphasis on triceps. There is huge amount of such subtle changes in workout and fitness in general. If you want to make you traaining efficient then you always have to think what you do and why you do it squeezing maximum from every set.