PNF (proprioceptive neuromuscular facilitation): The best method for flexibility?
To this day, scientists have been discussing the advantages and disadvantages of different stretching methods. Current studies show that stretching based on the principle of proprioceptive neuromuscular facilitation is superior to other methods for many reasons.
Both active and passive mobility can be improved by PNF stretching, whereby the latter is particularly in the foreground. When used correctly, the strength and endurance of the stressed muscles also are strengthened, so the stabilization and mobility of the joints, but also the neuromuscular control with regard to the coordination of the target muscles improve. The interplay of contraction and relaxation also reduces an increased tone in the muscles. Overall, PNF stretching increases the performance of the trainee on several levels. Furthermore, with other stretching methods, the physiological adjustment or improvement takes several weeks or months. Studies show that the PNF method can quickly increase the amplitude of movement. The combination of temporal and functional effectiveness makes PNF stretching a very attractive method for improving mobility. So you see, the PNF method has a lot of advantages. Now we need to look at the application of PNF Stretching.
The PNF Stretching method can be described as a form of stretching training, which wants to use receptor reflexes. So, stretching according to PNF includes an active and a passive part and - depending on the application - uses reciprocal (after contraction of the antagonist) or autogenic inhibition (after contraction of the agonist), or both. The use of the autogenic or reciprocal inhibition could sometimes be the cause of the high effectiveness. The method used here is “Contract Relax Antagonist Contract” (CRAC), which means that after maximum isometric contraction, a relaxation phase follows before stretching and the antagonistic muscles are contracted (see in Figure 1).
Figure 1 PNF Stretching (Source: https://prehabexercises.com/wp-content/uploads/2015/04/PreHab-Exercises-Effective-Stretching-Techniques-Examples-of-PNF-Stretching-e1430889946588.jpg, Retrieved on 08.09.2021)
But how does it work that you improve flexibility so fast? Therefore, we need to look at the different parts of the body which are involved. Important proprioceptors for mobility training after PNF are the Golgi organ and the muscle spindles. The former is located in the transition between muscle and tendon and perceives how the force on a joint change. The muscle spindles are located in the muscle belly and recognize length and kinetic changes. First, the muscle contraction of the agonist stimulates the afferent Ib nerve fibers of the Golgi organ and causes an action potential that is passed on to the spinal cord. After the agonist contracts for about six seconds, the Golgi apparatus relaxes, thereby reducing the resistance to stretching. This effect is known as autogenic inhibition and enables athletes to stretch beyond the limit of mobility. With the same approach, reciprocal inhibition can be described. The only difference is, that for the reciprocal inhibition you need to contract your antagonist to improve the mobility of the joint. If you use both inhibition forms, you will get the most advantage.
Figure 2 Autogenic and Reciprocal Inhibition (Source: https://i2.wp.com/www.differencebetween.com/wp-content/uploads/2020/01/Difference-Between-Autogenic-and-Reciprocal-Inhibition_1.jpg, Retrieved on 08.09.2021)
So you see, PNF Stretching will be a good method to increase your flexibility. But, therefore you need to consider a lot of things. Otherwise, you won´t receive all benefits of the PNF method. For this reason, I will present you with a short PNF Stretching Plan on Thursday with the most important exercises.
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