We will now describe the concept of stress and its diverse aristae, also including here answering mechanisms to stress whether acute or chronic, and making a reference to the Adrenal Pituitary Hypothalamus Axis. We will be interested in analyzing marathoners as opposed to sedentary men during exercising situations in order to describe adaptation mechanisms.
We will analyze exercising from an adult point of view. However, we have to understand that in women there will exist some different characteristics (particularly hormonal) related to the muscle mass. Women have a smaller water percentage because, due to hormones, they possess a higher proportion of fat. Masculine hormones are androgens, and the feminine ones are the estrogens and progesterone. There are masculine hormones in women and feminine ones in men. Hormones are produced by sexual glands (testicle and ovary) and inside the suprarenal gland (mainly androgens). Thus, women with high androgens will have lots of facial hair, acne, high muscular mass, oldstronger factions. In general, this is not due to androgen production in the ovaries, but in the suprarenal glands. Feminine hormones will provoke a major level of adipose tissue than in men. Testosterone, on the other hand, is related to muscular mass and aggression. Maximum contractile strength is the same in men and women and this is considered as the maximum strength produced per square centimeter of muscle surface. Maximum contractile strength is of 3 to 4 kg per sq. centimeter. Women, however, have two thirds of a man’s muscular mass. A lower muscular mass will provoke a lower performance in strength tests. This phenomenon does not repeat in exercises related with liquid retention (hydro saline equilibrium) such as: diving, swimming, sub aquatic activities. The Mancha Canal swimming record is held by a woman. This is related to her pregnancy preparation and to women’s ablest respiratory capacities.
Response and Adaptation: two different concepts.
If we climb a stair we will agitate ourselves. There will be a response which will end as soon as the exercise finishes. This is what we call response to exercise. Adaptation, instead, is a long term process which will be the result of prolonged and frequent training. In order to analyze adaptation what interests us the most is to focalize in a marathoner’s physiological characteristics and compare them with normal values of sedentary individuals. There is always a doubt in physiology books. Is there a genetic base by which these individuals are always predisposed to exercise or, on the contrary, are changes produced because they exercise? That is the question. Moreover if we take into account there are two types of muscular fiber.
Analysis of a "marathoner"
In a marathoner the volume minute is 90% superior to any sedentary man.
Lung volume (current volume times respiratory frequency, which means the air quantity that enters the lung as opposed to alveolar volume which is the one that will perform gaseous exchange) will be 65% superior to that of a sedentary man.
If a marathoner is making a high performance exercise, he has a 35% margin in order to reach maximum capacity. His margin in alveolar volume is only of 10%. This means that the capacity of rising the volume minute which will be his top cardiac capacity is lower, since the heart is functioning at his maximum level. In aerobic exercise (isotonic contraction) the most important limiting system is the cardiac one, the heart. If I raised my lung volume some more, that oxygen which I would add to my body will not be able to diffuse in order to generate a better performance, a greater energy, since the volume minute (blood going from the heart to the tissues transporting that oxygen) reached his maximum point.
The cardiovascular apparatus will be the limiting one since it is working at a capacity of 90%. Therefore, a marathoner best physiological advantage is his cardiovascular capacity not his respiratory one. So, this is what a marathoner is interested in working the most: his cardiovascular capacity (not his respiratory) since this will be the one that might limit his exercise.
Respiratory capacity will mainly influence resistance exercises, aerobic exercises in marathons and not the speed races (100 plain meters). A marathon runner will have as a main advantage a raise in the lung diffusion of oxygen. A sedentary individual doing exercise will transport 68 ml/min of gases through this membrane, whereas a marathoner will transport 80.
As for the cardiovascular system a marathoner will have a left heart hypertrophy. It is important to comprehend that in this case “dose makes the poison”. An excessive hypertrophy is counterproductive, reduces cardiac capacity through diminishing the volume minute. In this case a marathoner will show a “sane” hypertrophy which will raise the volume minute. The same stimulus will produce contradictory actions depending on the dose. Thus, a marathoner while doing exercise will show a 270% higher volume minute that during his rest. He selectively raised his capacity to pump blood towards tissues in exercise, reaching a 40% improvement over a sedentary man. During rest, this figure (5.5 liters) will be the same in both individuals.
A higher cardiac raise and a lower respiratory possibility show why during exercise, the cardiac factor will be the limit.
Why do these adaptations take place?
STRESS CONCEPT
Hans Selye is one of the forefathers of the stress concept. He defined it as an organism non specific response before any sort of demand, before a stimulus. He observed that before a stimulus from aggressive substances of any sort (cold, heat, trauma, psychological), different species’ organisms have a similar response. He called this response general adaptation syndrome. There exists a whole group of processes which start within the organism that respond in analogous manners to any sort of stimulus. This response arouses before fasting and exercise.
Stressor stimulus is not necessarily a bad one, it does not necessarily hurt. Playing a soccer game or making love represents a great joy. They are necessary in life. Selye used to say: “once there is no stress there is just death”.
Claude Bernard enounced that any change in the external world will produce an alteration in the organism against that natural ability which live beings possess to set an equilibrium process, towards equilibrium in the internal world and that these modifications will deviate this equilibrium in order to try to reestablish it.
If we climb a stair we will agitate ourselves. There will be a response which will end as soon as the exercise finishes. This is what we call response to exercise. Adaptation, instead, is a long term process which will be the result of prolonged and frequent training. In order to analyze adaptation what interests us the most is to focalize in a marathoner’s physiological characteristics and compare them with normal values of sedentary individuals. There is always a doubt in physiology books. Is there a genetic base by which these individuals are always predisposed to exercise or, on the contrary, are changes produced because they exercise? That is the question. Moreover if we take into account there are two types of muscular fiber.
