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Living Healthfully - June 2009

Effects of Exercise on Endocrine Secretions

Physical exercise is associated with marked metabolic changes and elicits a variety of neuroendocrine response (Scheen et al., 1998). These endocrine responses primarily aim to provide energy and growth needed by the body in order to keep up with the metabolic demands of a specific activity or exercise. And the endocrine system does this by controlling the metabolism of different energy sources like carbohydrates, fats, and proteins.

However the said responses would present themselves in varied forms depending on the type of activity or exercise an individual is performing-as for example, whether anaerobic or aerobic in nature. The reason for this is that different types of activities require different resources for energy and growth. And the fuel that energizes the body in anaerobic exercises is different from that which energizes the body in aerobic exercises.


Anaerobic Exercise versus Aerobic Exercise

If an individual is involved in sports or exercise with repeated short bouts such as baseball and sprint, the said individual is performing varieties of an intense exercise or anaerobic exercise. And intense exercise utilizes an energy system that refrains from using oxygen.

Ironically anaerobic or intense exercise is characterized by maximum oxygen consumption (VO2 max) of greater than 80 %. But despite of the huge accompanying increase in VO2, this type of exercise is almost entirely dependent on glucose and glycogen (coming from carbohydrates) for energy, which do not require reaction with oxygen for them to be utilized. The processes by which glucose and glycogen are transformed into energy are known as glycolysis and glycogenolysis, respectively.


In contrast, low- to- moderate intensity exercises like marathon or jogging, with 80 % or less VO2, greatly consume energy from system in which oxygen is of great importance. These low –to- moderate intensity exercises are therefore classified as aerobic.

In an aerobic type of exercise, glucose from carbohydrates are still used to produce energy, but not for long. Early glucose use is progressively supplanted by fatty acids use (from lypolysis) and at times glucose utilization from protein metabolism (known as gluconeogenesis). These energy sources necessitate oxygen reaction in order to produce the needed energy (Marliss and Vranic, 2002).

Endocrine Response Proper

Table 2 summarizes the major hormonal responses during exercise. It also describes the events that trigger the release of such hormones and the tissues in which they will be reacting with.



TO BE CONTINUED...
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Introduction

Exercise, as we all know, refers to bodily exertion for the sake of training or improvement of health (de Lisa et al., 1998). This improvement has been brought about by various adaptations by the body, including increased muscular strength, better blood circulation and blood pressure management, and other systemic responses. Aside from this, the bodyÂ’s ability to provide energy is also continuously modified with sustained training in order to keep up with the energy demands of the activities involved. And in order to do these, all of the systems must work synergistically. One of the systems that contribute in the process is the endocrine system.

The Endocrine System

The endocrine system is one of the several types of communication systems in the body interplaying to coordinate the multiple activities of cells, tissues, and body organs. This system is composed of glands or specialized cells that release into the circulating blood, chemicals known as hormones that influence the functions of cells at another location in the body (Guyton and Hall, 2000). Through various hormones, the endocrine system is able to provide stability to the bodyÂ’s internal environment, since these substances exert biological response affecting humanÂ’s growth, development, reproduction, and even augmenting the bodyÂ’s capacity for handling physical and psychological stress (Marks and Kravitz, 2000).

Classifications of Hormones

According to John Scott (Scott Fitness Personal Training), there are four general classes of hormones: (1) proteins and polypeptides, (2) steroids, (3) biogenic amines, and (4) eicosanoids. These classifications are based on their chemical structures or organizations.

Peptides are short chains of amino acids while proteins are much larger and more complex arrangements of amino acids or peptides. Examples of which are insulin secreted by the beta cells of the pancreas, somatotropin or the human growth hormone and the thyroid stimulating hormone released by the anterior pituitary gland, parathormone from the parathyroid gland, antidiuretic hormone by the posterior pituitary gland, and many more.

Steroids, on the other hand, are distinguished structurally by their basic four-carbon ring backbone. Examples are cortisol coming from the adrenal cortex, estrogen and progesterone secreted by the ovaries and placenta, and testosterone from the testicles.

Biogenic amines are structurally the simplest hormones. Modifying single amino acid forms these hormones. Some of the variations include the catecholamines (epinephrine and norepinephrine) released by the adrenal medulla, triiodothyronine secreted by the thyroid glands, and histamine secreted by platelets and mast cells.

Eicosanoids are primarily synthesized in cell membranes of almost all cells by adding oxygen atoms to arachadonic acid. They include prostaglandins, thromboxanes, leukotrienes, and lipoxins.

Endocrine Glands, Hormones, and their Functions and Structures

Table 1 briefly discusses the functions of each of the endocrine glands and how their hormones contribute in maintaining the bodyÂ’s homeostasis or internal balance. It would be advantageous if we take note of those endocrine glands and hormones that control glucose, fat, and protein metabolism, since knowledge of those could be helpful when we discuss endocrine responses to exercise.


Table 1a


Table 1B


Table 1c


TO BE CONTINUED...

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On Knee Pain

June 22nd 2009 16:54
E.W., from HongKong asks:
"I am a 16 year old student. And I need to go to my classroom on the second floor every weekday morning. But as I climb the stairs, I usually feel pain on my right knee- after two or three steps. What may be the possible problem on my knee? Thank you!"

MY REPLY:

Hi E.W.! Well it is very difficult to say or even assume what causes your knee pain. What I usually do is that I carefully and intensively inspect not just the knees but the whole posture of an individual from head to toe. I believe that the body parts are closely and kinematically linked to one another. And a change on a normal orientation/ configuration of any part may affect the rest of the parts of the body. And so it is best to consult an orthopedic doctor or a physical therapist to further evaluate your knee problem.

Nevertheless i know of a condition that usually affects people at your age. And I do hope that the succeeding parts may help you and our readers.

The problem I am talking about is a condition known as patellofemoral pain syndrome.

What is patellofemoral pain syndrome? It is pain associated to faulty alignment of the patellofemoral joint.

The patellofemoral joint is an articulation between the knee cap and the tip of the thigh bone. Normally the knee cap has to be placed centrally over the tip of the thigh bone.

Normal knee
NORMAL KNEE


But because of faulty body alignments and muscular imbalances the patella is deviated away from the center-usually outward.

knee pain
PATHOLOGIC KNEE


And so a patient, when he alternately bend and extend the affected knee, can experience pain because the patella (knee cap) is being dragged against the rough surface of the thigh bone.

In E.W.'s case, the above condition may be showcased when going up the stairs.

Previously I mentioned that the affectation can be caused by poor body alignment and muscular imbalance. Examples of poor body alignment are when a person is flat-footed, has wide pelvis, resulting to genu valgus. All of these result in abnormal outward translation of the knee cap. Look at the child in this illustration.

genu valgus
The knees of this child manifest with genu valgus.


Example of muscular imbalance is when the muscles pulling the knee cap sideward are stronger than the muscles pulling the knee cap medially. Normally the strength has to be equal to place the knee cap at the center.

TO BE CONTINUED...
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Multiple sclerosis

June 20th 2009 14:24
multiple sclerosis
Multiple Sclerosis- from www.ahealthyme.com



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What is Multiple Sclerosis?

June 18th 2009 09:41
Multiple Sclerosis (MS) is a problem on the body's central nervous sytem. We probably hear this condition less frequently as other CNS diseases, but this is somehow degenerative, progressive, and debilitating.

Some say that MS is an auto-immune disease, very much similar to Rheumatoid Arthritis (RA)... Auto-immune diseases are those characterized by the activation of our white blood cells and immune responses against our own body parts.

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Issues on Adolescence (Part 3)

June 17th 2009 14:19
Physical Changes

Puberty is a physical process of change characterized by the development of secondary sex characteristics. We must understand that puberty differs from adolescence. Puberty happens synchronous with adolescence, but adolescence does not only highlight physical changes, but (largely) also psychological ones


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Issues on Adolescence Continued

June 14th 2009 12:26
Adolescence is commonly divided into three periods: early (11 to 14 years of age), middle (14 to 17 years old), and late (17 to 20 years). These divisions may overlap each other. And development taking place in each phase varies from one individual to another. And so this discourse shall discuss the typical growth and development an individual goes through along adolescence as a whole. Discussion of such will be two-fold: physical and psychosocial.

Before we proceed, it is nice to know that societies have their own ways, rites, or icons that mark an individual’s entry to adolescence. As adolescence is a transition between being a child and assuming the duties and responsibilities of an adult, some societies would test an adolescent’s (especially male) bravery and endurance by providing a challenge or activity (Atkinson). In Jewish rites, the bar mitzvah would entitle an adolescent into engaging in early marriage (Jewish Encyclopedia, 1901-1906). In the Philippines, one of important markers of adolescence among male is circumcision. Nevertheless, almost all societies in the world would unquestionably associate adolescence with puberty. As a matter of fact, puberty may somehow summarize all the significant physical changes an adolescent may undergo


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What Vitamins are Not?

June 12th 2009 03:24
I remember way back in my biochemistry class- not so long ago- my Doctor-Professor use to say the following facts about vitamins. And I guess this may help readers to clear things out about the supplements available in the market today.

WHAT VITAMINS ARE NOT?

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Issues on Adolescence

June 10th 2009 12:22
Adolescence

youth
How good it is to see the youth involved in meaningful activities like serving the Church!

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Psychosocial Needs of the Elderly

June 8th 2009 05:59
The Importance of Meeting an Individual’s Psychosocial Needs


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I've written an article about our back and how it affects posture. I feel that it was a good feature that needs recalling...HERE'S THE LINK.

_____________


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