A Definition of Aerobics:
Aerobic Respiration and Exercise

I would find it quite simple to provide a definition of aerobics if I only knew the question you were asking. I obviously know that you are not seeking a dictionary definition that could be anything depending on the knowledge of the lexicographer, but it helps when such a question is asked to understand what you have in mind when asking it.

Here are two possible definitions to offer an example of why I might seem to be awkward here. I don't mean to be, believe me. I am here to help you, but sometimes in matters of science and health we have to be very specific in the questions we ask in order to get the answer we want, and the term 'aerobics' is an example.

Or perhaps not on reflection, because by using the term 'aerobics' you likely mean aerobic exercises. However, irrespective of that, here are two explanations, each a valid definition of aerobics.

Some Background on Anaerobics

The word 'aerobics' has its root in the Greek for 'with oxygen', so aerobic exercise is exercise that involves oxygen. It might surprise you that exercise that involves you breathing needs a special word! After all everybody breathes when they exercise, don't they, and you have never seen anybody running a marathon on one breath for goodness sake! So why do we need a special definition of aerobics?

In fact, you would be wrong to claim that everybody uses oxygen when they exercise! I bet that surprises you, doesn't it? Well if it does, just think a little. How about a weight lifter who suddenly slams a ton of metal above his head before he can draw one breath: does he need oxygen to do that?

How about Linford Christie when he won his Olympic Gold in the Barcelona Olympics? Did you see him take even one single breath during his winning run in the final - or were your eyes on another famous part of his anatomy?

Short term physical endeavor that lasts less than two minutes can be carried out without the need for oxygen - it is referred to as anaerobic respiration, where ATP energy can be generated without the involvement of oxygen. The energy basically comes for your body's emergency short-term energy stores, of which you have three:

0-5 Seconds:
For the first 5 seconds your body uses up the ATP energy that is stored within your muscle tissues. Sprinters in particular use this up quickly.

5-10 Seconds
Then for the next 5 seconds your body starts using its creatine phosphate stores, and after that it resorts to your muscular glycogen stores. So, Linford (and Carl Lewis) can run a full 100 meters and more without a single breath.

Over 10 seconds
After that, the middle distance runners progressively start to use oxygen until by around 4 minutes; it is entirely aerobic energy that is being used.

Scientific Definition of Aerobics

So, that is what anaerobics is. In order to define a term it is often first necessary to define its opposite, so that you then understand why the initial term exists. Without anaerobic energy, there would be just 'energy' so need for the term 'aerobic energy'. There's a name for that way of defining a word but I can't recall it right now. Answers on a postcard to. . .

So by now it is obvious to you that the definition of aerobics is 'needing oxygen', or as the Greek translation gives us: 'with oxygen'.

Aerobic respiration is cellular respiration, where oxygen is used to oxidize glucose to carbon dioxide and water with the release of ATP energy. For the more technically minded, oxygen, being an oxidation agent, is an electron acceptor, and is the final electron acceptor in the electron transport chain where oxidative Phosphorylation takes place, adding to the ATP energy already generated in the Krebs or Citric Acid Cycle.

Popular Definition of Aerobics

After all that, now let's get down to what you probably really mean by the definition of aerobics. Aerobic exercises.

In that respect, 'aerobics' is exercise that uses up a lot of oxygen: you have to breathe a lot. This gets more oxygen into your lungs, which is then transferred to your blood by means of the oxidation of hemoglobin in your red blood cells to oxyhemoglobin.

In doing this, the oxygen in your lungs is exchanged for the carbon dioxide emitted from one of the reactions in the Krebs Cycle, and the CO2 is expelled when you exhale prior to breathing in more oxygen for this wonderful exchange mechanism that takes place in the alveoli of lungs where gases can pass through the thin membrane separating the outside world from the wonders of your personal internal plumbing system known as veins, arteries and capillaries.

Because you are carrying out strenuous exercise over protracted periods of time, your heart beats faster to provide enough oxygen to your muscles and so more oxygen and more nutrition is passed to your muscles.

Getting Hooked on Exercise

As described under the definition of anaerobics above, your initial energy usage is largely from your internal emergency energy stores but after a couple of minutes you use up the glucose in your blood obtained by the metabolism of the carbohydrates in your diet.

You will feel good exercising, no doubt about it, and strenuous exercise release endorphins in the brain - polypeptide proteins whose name is derived from the two words 'endogenous' and 'morphine' and are a true 'legal high'.

They are produced in the pituitary gland at the base of the brain, and attach to neuroreceptors in your brain and not only relieve pain, but give a morphine-like 'high'. However, I digress through excited thinking! As an aside though, to be serious here, that is why some people can get literally hooked on exercise. It's a fact!

Back to Definition of Aerobics.

After you have used up the bulk of the blood glucose that originates from your diet, continued aerobic exercise will break down fats in your fat cells. You are born with a certain number of fat cells that have throughout your life barring damage, and the can be anything from empty to full.

Once your aerobic exercise has used up your glucose stores, your fat is the next target for your metabolism, and that's when you lose weight and start to get slim.

So that, basically, is how aerobics works. You undergo sufficient exercise involving breathing that you run down your body's blood glucose stores. You then burn the fat in your fat cells, and not only lose weight but start to look slimmer.

Aerobic exercise can be as simple as jumping up and down waving your arms about, to strenuous circuit training that also includes an element of working specific muscle groups so that you can target the areas from which you lose fat. If you simply jog you will lose fatty tissue, but not necessarily from your booty or your thighs or your tummy.

Start exercising the large muscles in your buttocks (the gluteus maximus is the largest muscle in your body - yes, even yours!), your thigh muscles and do some curl ups and toe touches and you will soon start to see a difference in these targeted areas. However, there is one major 'but'! (and it's not yours - that has an extra 'T').

You must use up more calories when you exercise that you eat. If not, you will never lose weight. If your take in more energy than you use, you will put on weight no matter how much exercise you do - unless. . .

You exercise you muscle groups and these calories are in the form of proteins! Then you will still put on weight, but it will be muscle weight as the proteins are deaminated to release the carbohydrates they contain for energy, and the amino acids that are freed into your blood will be used to build up muscle tissue, not to fill up your fat cells.

So that's the best definition of aerobics I can give you. I hope you read it all!

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