The reaction speed is the ability that it allows us to react with a certain speed before stimuli, indications or signs.

Zaciorski wrote that the processes that take place in the individual since the stimulus takes place until the physical reaction, distinguishing five phases:

1. Perception, with the appearance of an excitement in the receiver (eye, heard, skin)

2. Transmission of the excitement to the Central Nervous System.

3. Treatment of the information that would be the step from the stimulus to the nervous system and the formation of the answer (phase of decision if it was necessary).

4. Arrival to the muscle of the sign of the Central Nervous System.

5. Stimulation of the muscle operated by the Central Nervous System and the appearance of the movement.

The process is complex and it is hence difficult to reduce the time of latency to the minimum.

The body, on the other hand, has programmed certain reflections that protect it before situations that commit its survival or to respond to very simple situations regarding those that have to adapt without thinking (stretching reflection, of straightening, etc).

The reflections express the quickest answer to a stimulus, because it stops their answer, it is not needed that the information arrives until the brain to choose, but simply to the spinal marrow to emit an automatic answer, with what the process is speeded up and the time of reaction is quicker. The journey of the stimulus is shorter, and it disappears the time of decision.

The simplest reflections leave of the spinal marrow, and as we go ascending towards the brain they leave elaborating the most complex answers.

The sensorial information travels at all the levels of the nervous system and it causes the corresponding answers, for that oneself stimulus produces different reactions, and it can combine reflective and voluntary answers.

For example, the stretching reflection, for which the abrupt stretching of the muscle provokes a reflective contraction of the same one to return to its initial longitude, it can be taken advantage of to carry out jumps and another type of elastic movements.

In the exit of heels for a career of speed, we can take advantage of the fall reflection to get a quicker answer to the exit stimulus. For that reason, the position of exit of heels requires a certain imbalance toward before.

We will continue speaking of the speed of voluntary reaction and their possibilities inside the physical activity.