INTRODUCTION
Much of the early information about exercise and medicine appeared in the ancient, medieval, and Renaissance medical literature in the context of the "six things nonnatural” [1].
These were the things that were under everyone's own control, directly influenced health, and became the central part of the new "physical education" movement in the early 19 century in the United States.
They were known then as the "Laws of Health”.
Until the early 1900s, "physical education" was dominated by physicians who specialized in health and exercise.
However, physical education changed to a games and sports curriculum led by coaches who introduced competition and athletic achievement into the classroom.
As that happened, physicians disappeared from the profession.
THREE SPECIAL CATECHOLAMINES
During exercise our body release in blood three differents catecholamines which are epinephrine, norepinephrine and dopamine are three neurotransmittor which are account in the family of catecholamines; let's go through them one by one.
EPINEPHRINE
As a hormone and neurotransmitter, epinephrine acts on nearly all body tissues.
Its actions vary by tissue type and tissue expression of adrenergic receptors.
For example, high levels of epinephrine causes smooth muscle relaxation in the airways but causes contraction of the smooth muscle that lines mostarterioles.
Epinephrine acts by binding to a variety of adrenergic receptors.
Epinephrine is a nonselective agonist of all adrenergic receptors, including the major subtypes α1, α2, β1, β2, and β3.
Epinephrine's binding to these receptors triggers a number of metabolic changes.
Binding to α-adrenergic receptors inhibits insulinsecretion by the pancreas, stimulates glycogenolysis in the liver and muscle, and stimulates glycolysis in muscle.
β-Adrenergic receptor binding triggers glucagon secretion in the pancreas, increased adrenocorticotropic hormone (ACTH) secretion by the pituitary gland, and increased lipolysis by adipose tissue.
Together, these effects lead to increased blood glucose and fatty acids, providing substrates for energy production within cells throughout the body.
| Organ | Effect |
| Heart | Increases heart rate |
| Lungs | Increases respiratory rate |
| Systemic | Vasoconstriction anda vasodilatation |
| Liver | Stimulates glycogenolysis |
| Systemic | Triggers lipolysis |
| Systemic | Muscle contraction |
NOREPINEPHRINE
It is the hormone and neurotransmitter most responsible forvigilant concentration in contrast to its most chemically similar hormone, dopamine, most responsible for cognitive alertness.
Areas of the body that produce or are affected by norepinephrine are described as noradrenergic.
The terms noradrenaline (from the Latin) and norepinephrine (from the Greek) are interchangeable, with noradre naline being the common name in most parts of the world.
However the U.S. National Library of Medicine has promoted norepinephrine as the favored nomenclature, and this is the term used throughout this article.
One of the most important functions of norepinephrine is its role as the neurotransmitter released from the sympathetic neurons to affect the heart.
An increase in norepinephrine from the sympathetic nervous system increases the rate of contractions in the heart.
As a stress hormone, norepinephrine affects parts of the brain, such as the amygdala, where attention and responses are controlled.
Norepinephrine also underlies the fight-or-flight response, along with epinephrine, directly increasing heart rate, triggering the release of glucose from energy stores, and increasing blood flow to skeletal muscle.
It increases the brain's oxygen supply.
Norepinephrine can also suppress neuroinflammation when released diffusely in the brain from the locus coeruleus.
When norepinephrine acts as a drug, it increases blood pressure by increasing vascular tone (tension of vascular smooth muscle) through α-adrenergic receptor activation; a reflex bradycardia homeostatic baroreflex is overcome by a compensatory reflex preventing an otherwise inevitable drop in heart rate to maintain blood pressure.
DOPAMINE
In the brain, dopamine functions as a neurotransmitter -- a chemical released by nerve cells to send signals to other nerve cells.
The brain includes several distinct dopamine systems, one of which plays a major role in reward -- motivated behavior.
Every type of reward that has been studied increases the level of dopamine in the brain, and a variety of addictive drugs, including stimulants such as cocaine, amphetamine, andmethamphetamine, act by amplifying the effects of dopamine.
Other brain dopamine systems are involved in motor control and in controlling the release of several important hormones.
Several important diseases of the nervous system are associated with dysfunctions of the dopamine system.
Parkinson's disease, a degenerative condition causing tremor and motor impairment, is caused by loss of dopamine-secreting neurons in the midbrain area called the substantia nigra.
There is evidence that schizophrenia involves altered levels of dopamine activity, and the antipsychotic drugs that are frequently used to treat it have a primary effect of attenuating dopamine activity.
Attention deficit hyperactivity disorder (ADHD) and restless legs syndrome (RLS) are also believed to be associated with decreased dopamine activity.
Outside the nervous system, dopamine functions in several parts of the body as a local chemical messenger.
In the blood vessels, it inhibits norepinephrine release and acts as a vasodilator; in the kidneys, it increases sodium excretion and urine output; in the pancreas, it reduces insulin production; in the digestive system, it reduces gastrointestinal motility and protects intestinal mucosa; and in the immune system, it reduces the activity of lymphocytes.
With the exception of the blood vessels, dopamine in each of these peripheral systems has a "paracrine" function: it is synthesized locally and exerts its effects on cells that are located near the cells that release it.
A variety of important drugs work by altering the way the body makes or uses dopamine.
Dopamine itself is available for intravenous injection: although it cannot reach the brain from the bloodstream, its peripheral effects make it useful in the treatment of heart failure or shock, especially in newborn babies.
L-DOPA, the metabolic precursor of dopamine, does reach the brain and is the most widely used treatment for Parkinson's disease.
Dopamine-activating stimulants such as cocaine, amphetamine, and methylphenidate (Ritalin) are addictive in high doses, but are used at lower doses to treat ADHD.
Conversely, many antipsychotic drugs act by suppressing the effects of dopamine.
Drugs that act against dopamine by a different mechanism are also some of the most effective anti-nausea agents.
THE IMPORTANTCE OF SPORT…
Physical exercise is one of the life-style modifications used for lowering blood pressure.
Except for diminished norepinephrine spill over, the mechanism by which physical exercise exerts its effects was not known.
We have revealed that mild exercise reduces plasma volume and hence the cardiac index.
In order to elucidate the mechanism, we have investigated all possible parameters relevant to plasma volume regulation.
Among them, urinary free dopamine and urinary active kallikrein increased in the early stages (weeks 2-4) while atrio-natriuretic factor (week 4) and endogeneous ouabain-like substance (EOLS) consequently (weeks 7-10) decreased.
Serum taurine increased and plasma norepinephrine decreased in the late stages.
The conclusion reached is that mild exercise seems to first activate the renal dopamine and kallikrein systems and second trigger other mechanism, such as an increase in taurine and decreases in EOLS and norepinephrine.
…AT ANY AGE..
It is important to note that in older adults with one or more chronic diseases, exercise training may be considered a therapy, and such adults should begin an exercise program designed to safely and efficiently treat their disease.
However, they should also perform the exercise recommended for disease prevention to prevent the development of an additional chronic condition.
Moreover, when chronic diseases or even a lack of time prevent older adults from achieving the minimal exercise/physical activity recommendation, they should still engage in exercise (type, quantity, intensity and frequency) accord to their capacity and clinical condition, always trying to avoid sedentary lifestyle because even exercise levels below (mainly in quantity) the minimum recommendation have demonstrated health-related benefits.
Although the aging process (and consequently death) is inevitable, a sedentary lifestyle can accelerate its progression by decreasing physical (cardiorespiratory and muscular) fitness and increasing sarcopenia and the incidence of chronic diseases.
Moreover, regular exercise and/or physical activity practice may improve the quality of the years lived, in addition to increasing life expectancy.
The data presented in the review provide convincing evidence about the importance of engaging in regular exercise and/or physical activity programs throughout life to improve health and the quality of life and to prevent chronic disease during aging.
…AND AGAINST DEPRESSION!
Recent research has shown that pro-inflammatory cytokines not only induce "sick symptoms", but also impinge on physically ill patients by leading to depressive disorders.
In approximate 33% of patients who are treated by recombinant human cytokines interleukin-2 (IL-2) and interferon- (IFN- ) major depressive disorder is observed.
It has been shown in animal models of inflammation that existing states of decreased reactivity to reward (anhedonia) and reduced social exploration can be reversed by antidepressant treatment.
Exercise has been shown to influence the immune system and seems to play an important role in the relationship between the immune function and depressive disorders.
During exercise, the cascade in cytokine response differs from the "classical" response to infections represented by the onset of circulating IL-6 during exercise.
Epidemiological data suggests a relationship between physical inactivity and low-grade inflammation in healthy subject.
Exercise works as an anti-inflammatory agent by leading to higher levels of IL-6 which is followed by raising IL-1ra and IL-10 levels and also by suppression of TNF- production as demonstrated in animals and in vitro studies.
Exercise gives rise to high levels of epinephrine that has also been shown after infusion to inhibit TNF- production in response to endotoxin in vivo.
Except for strenuous exercise which is mainly pro-inflammatory, the exact dose of exercise that has anti-inflammatory effects has not been clearly established.
However, the data suggests that moderate aerobic exercise seems to induce the most promising effects considering the anti-inflammatory and antidepressive outcomes.
