Basic physiology of resistance exercise

Voluntary movements of the human body occur thanks to muscle contraction/relaxation generated by nervous stimuli. These stimuli work in a binary way (they activate or they do not activate) and the strength of the muscle does not depend on the intensity of the stimulus but depends on two factors:

1. The section of muscle fibers that are activated by the stimulus or simply put, however large the diameter of the muscle is. The greater the section, the greater the force.
2. The number of muscle fibers that are simultaneously activated by the stimulus (or what is technically known as the recruitment capacity of the motor neuron). The greater recruitment, the greater force.

Knowing this, he more muscle mass we have and the greater capacity to mobilize it at the same time, the greater the levels of strength although it should be pointed out that in resistance activities, the weight/power ratio is of paramount importance. Therefore, greater muscle mass can represent higher levels of strength but lower levels of performance, especially when you have to fight against gravity. However, higher levels of recruitment will always mean higher levels of performance. From the above statements, it can be deduced where strength work should be directed during training: recruitment before hypertrophy.

The performance in resistance activities related to the neuromuscular system is the result of the work carried out with the muscles involved in the technical movement of each sporting activity. A drop in performance is explained by a drop in the ability to produce force that originates at the central level (in the nervous system) and/or peripherally (in the muscular system) and that can materialize , in isolation or simultaneously in:

1. Centralfatigue
   1. Less ability to simultaneously recruit muscle fibers. Therefore, fewer fibers working at the same time, less force and less range of motion.
   2. Lower frequency of electrical stimuli. Therefore, fewer calls to the fibers to work, less frequency of contraction and less frequency of movement.
   As a clear example in this regard, central fatigue is what causes us that the more distance we have run in a certain race or training session, the shorter the length and frequency of the stride, with the same number of heartbeats, the lower the speed.
2. Peripheral fatigue
   1. Alterations in the reception of the electrical message that generate disturbances in the process of muscular contraction/relaxation.
   2. Fall in the intrinsic capacity of muscle fibers to generate force.
   Another very clear example that we have all more or less suffered in terms of the disturbance of the electrical message would be the ramps caused by dehydration. These involuntarily cause unwanted contractions that do not allow movements to be executed correctly or with the desired intensity.

In general, all resistance activity practitioners tend to base all their training on the work of the cardiovascular system, disregarding any type of session related to strength and speed. And this is a mistake. It has been shown that the work of these two physical qualities improves performance in endurance activities thanks to an improvement in the mechanisms for the transmission of nervous orders, with which there is a direct contribution to the economy of the movements.

On a practical level, and thanks to current technology, we will be able to evaluate these levels of strength and efficiency and the evolution that training generates in these values. This will lead us to improve our training process and make greater use of our work sessions.