Archive for Diciembre, 2008
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.
Diciembre 29th, 2008
The ligaments are elements that help us to hold the articulations to prevent them moving in addresses in those that doesn’t have to make it.
In the mobile articulations the bone doesn’t hold the contact area totally with the other bone to allow the displacement and this way is able to carry out the movements.
The most mobile articulations are at the same time the most unstable (that is to say, those that less subject they are) and this gives cause to that in the movements the articulations can be come out of their place.
To hold the articulations without impeding the mobility of the bones we have these reinforced with the ligaments that are tapes of fibrous fabric that fix in the addresses in those that it could separate the articulation.
They have very little elasticity or any, and this it is an essential aspect so that they can complete their function of limit of the movements.
It not only prevents that the articulation moves for non wanted addresses , but rather they limit to the width of the movements of the articulation to maintain them inside the physiologic limits.
In this sense the ligaments receive information of the brain to perceive and to control the movements.
The ligaments receive the sanguine watering what will benefit their regeneration.
They are more important in the articulations of more mobility,as the shoulder and the hip that can be mobilized in the three plans of the space for example.
It will continue…
Diciembre 15th, 2008
The human is a hot-blooded animal and can keep the body temperature constantly, although in a changing atmosphere.
The physical training , the infections and other circumstances cause more heat to the organism.The metabolism can elevate between five and twenty and that creates more body heat.
An excess of atmosphere temperature,and / or relative humidity are factors that have influence in the heat accumulation,specially when we do physical training.
The heat excess has to be eliminated not to increase temperature and to change vitalitiy functions.The first mechanisms to heat elimination would be :
-Conduction: Heat is transferred to other object or person by physical contact directly, for example touching an ice.
-Convention:Heat is transferred by the movement of the air or when it has contact with water.For example :cycling,swimiming.
-Radiation:The body radiates its heat to the enviromental air.For example, if it is cold.
-Evaporation: Heat is eliminated changing sweat into steam.By breathing, the urine and faeces we also eliminate steam.
Resting and with enviromental temperature in the normal level,blood moves by conduction and convention the heat outside.
The bigger part of this is eliminated by radiation and convention.Its loss elevates if it is cold,more air and more surface in contact with other cold element.But for these factors are invested the body can get hotter ( for example, sunbathing ).
During the training,the evaporation is more relevant ,being neccesary the apparition of sweat.The sweat water is generated from the blood liquid,that moves to the skin when it begins to gather a heat excess.
This processmis regulated by the termoregulation mechanisms.The excess of humidity slows the evaporation down and the organism loses more water to dissipate the same amount of heat,dehydrating quicklier,affecting to termoregulation and preformance.
During the next chapter,we will go deeper in the consecuences of the liquids losing to the organism,that is a cuestion to have in mind specially when we are working with high temperatures and very hard efforts.
It will continue …
Diciembre 6th, 2008
