How The Body Works

Chapter 1

How the body works.

The body is a complex and phenomenal machine. With a collection of 206 individual bones in the adult skeleton, and approximately 640 muscles that support and move the skeleton, it can easily be seen how people can get bogged down with so much information that basics in human physiology can be overlooked when trying to deal with weight loss and the management of a healthy lifestyle.

When you talk about weight loss, it is not a lost cause, and definitely you do not need a degree to understand it, it can be easy to simplify things just a little, so that everyone can learn to live a much healthier and stronger life. Lets look at how the body works in general.

Every time you move a muscle, twitch a finger, walk, run, bend over or any other movement of a muscle, those muscles use energy. The amount of energy that is needed to make that gesture depends on that movement. Eg: The amount of energy taken to walk one step, is significantly more than the amount of energy required to raise your right arm parallel to the ground.

Why?

Because of the number of muscles involved in that particular movement.

I have been trying to work out the best way to describe to you how the body and muscles work in order to facilitate movement. Most probably, you take it for granted. Do you stop and think, ‘OK I want to move my arm now to pick up that cup, so I will send a message from my brain to my arm to use the muscles necessary to move my arm into a position to grab the cup’? No! You just pick up the cup. These movements of the muscles must use energy, in order to create that movement. I guess we can look at the muscles and their sizes in our body, and compare them to different types of cars.

If we look at the largest muscle group in our body, which are your leg muscles, we can compare them to a V8 engine in a car. The V8 will use more petrol to run than your standard 4-cylinder hatchback, even when idling. Your Basal Metabolic Rate (BMR) is like your body’s idling speed; I will go into depth later and tell you what that is all about, but basically it is what your body uses at rest. Then when you decide that you are going to go for a run, your body needs to get more fuel, because if you run out of fuel in a V8, we all know what happens then. During that run, your body has to get the fuel from somewhere, and that somewhere is the fat stores on your body.

So if we then take a muscle group a lot smaller in your body, like your arm, mainly your biceps for example, those muscles are smaller and need less energy when idling and during exercise. These muscles however, still need energy. You can see quite clearly how, a V8 engine car will use more energy/petrol than a 4cylinder hatch, can you also now see how larger muscles will use more energy than smaller muscles?

Knowing this, you have just been given the secret to increasing your idling speed; increasing the amount of energy that you will burn at rest every minute you are not doing something. The bigger your muscles become, the more energy they consume, and the more energy they need to be maintained. The energy that these muscles need to survive is explained in the next chapter.

 

The Energy Used in the Body.

The above is a very simple example in regards to energy consumption in the body. So let’s go a little deeper and talk about that energy which is the “calorie”. Let’s get the definition of a calorie out the way because everybody who wants to lose weight has some sort of phobia about the word calorie.

By definition:  a calorie (kilo calorie) and is the amount of heat required to raise 1 kg (1 L) of water 1 degree C 

So in the simple layman’s terms a “calorie” is a unit of measure of heat.  How then does this unit of measure called the calorie work back with the previous example? To explain this we need to look at the energy systems in the body.

Now I did say that this was a simple guide to weight loss, and that I wasn’t going to get technical, but unfortunately for this section I really have to. So strap in and put your thinking caps on, go grab a glass of water and really concentrate on what I am going to tell you.

The body is made up of 4 energy Systems.  These systems use body fat and carbohydrates in order to facilitate muscle movement.  How the muscles move is described in a section of theory called “The Sliding Filament Theory” and for those who want to really know how your muscles move, you can follow the link I have placed here.

http://www.ivy-rose.co.uk/Topics/Muscle_Sliding-Filament.php

Each of these energy systems plays a specific role when you are doing sport and it will depend on the type of sport you are doing as to which particular energy system you will use.

 

ATP-PC or Creatine phosphate system.

In your muscles, which are predominantly made up of protein, there is a certain amount of ATP (adenosine try phosphate) stored for an immediate muscle contraction.  ATP is ‘THE’ fuel that is used when you perform any type of movement. It is the fuel that your muscles use to contract for whatever reason.

If you were to do an activity that employs this system such as sprinting, swimming or climbing, and you performed this activity as fast and as hard as you can, the amount of ATP stored in your muscles “in general” would last only for 6-15 seconds, depending on the person.

Here is a little experiment for you to try out, fit or unfit. Go to your local oval and start at one end, set your stopwatch then run as fast and as hard as you can for as long as you can until you physically can’t move. That doesn’t mean slowing down until you can handle it, it means running flat out until you can not go any longer, and then check your stopwatch. You should see that you would fall into the 6-15 second band. Your muscles start to burn around 6-10 seconds as you completely expel all of the ATP that is stored in your muscles for contraction.

What is happening in this experiment is that you are constantly contracting and expanding your muscles to run, but your body is unable to reproduce enough ATP to continue the muscle contraction therefore you slowdown and tire very quickly. The ATP system lasts about 20-30 seconds, but as you pass this time-frame one of the other three energy systems in your body will start to take over.

Anaerobic Glycolysis

Around the 10 second to 15 second mark the ATP system begins to fade and what’s known as “Anaerobic Glycolysis” takes over.

For activities lasting anywhere from 30 seconds to 3 minutes, this anaerobic energy system is usually where the body get its energy supplies from. How the system works is it breaks down the muscle and liver glycogen stores without the use of oxygen. 

A by-product of this system is called ‘lactic acid’. Contrary to popular belief lactic acid is not responsible for the pain that you feel after intensive exercise 24-48 hours later. The pain you feel is the excessive mechanical force that you employed during your workout which resulted in damage to the muscular or connective tissue.  The pain you feel, is the stimulation of sensory nerve endings as the body begins to repair the damage done during exercise. That is why this usually occurs when you first start an exercise programme or when you train and at an unusually high intensity level.

Lactic acid is usually dispelled within 30 minutes to an hour after exercises finished.

Aerobic Glycolysis.

After about three minutes of exercise aerobic Glycolysis is the dominant energy system.  This energy system produces energy by breaking down muscle and liver GL stores with oxygen present. Because oxygen is present when the system is in use there is no build-up of lactic acid.

This system does not produce energy as fast as the ATP system or Anaerobic Glycolysis system, and therefore the intensity of this particular exercise cannot be as high. This system has the capacity to produce energy for about an hour or more.

 

Oxidative Phosphorelation

This energy system provides energy during the long, moderate to low intensity exercises. The system breaks down the body’s fat stores to supply energy to working muscles. As the intensity of exercise decreases the body relies more on this energy system. This energy system can supply virtually unlimited supplies of energy. Endurance sports such as cross-country running swimming soccer and lacrosse all rely heavily on their system.

The easiest way to explain how these systems work in real-life situations is to use running. Let’s say you were on a 400m track. If you were to run as hard and as fast as you can for as long as you can, you would last anywhere from 6-15 seconds. The energy system you have just depleted is your ATP or Creatine phosphate system. What would happen is you would deplete all of your glycogen stores in your muscles in 15 seconds and you would physically not be able to move your legs until that energy was replenished.

If however on the starting blocks you decided to run at 80-90% of your maximum energy output, you could keep going around the track from anywhere from 30 seconds to three minutes, depending on your fitness level. You would deplete the energy in your muscles but after 15 seconds Anaerobic Glycolysis would kick in and help to replenish ATP in your muscles. This would only last for around 3 minutes.

Again if you decided to run from the starting blocks at 70-80% of your maximum energy output, you would be able to circle the 400 m track for anywhere between 50 minutes to an hour or more, again depending on your level of fitness.

And finally if you were to run from the starting blocks at anything less than 70% the Oxidative Phosphorelation energy system would be the system that is used predominantly here and you could run for hours.

Now I realise that I said I would not get technical but these four energy systems needed to be explained in order to assist you in working out which exercise would best suit you for your fitness and weight loss needs.  

But the question I hear you ask is “what does this have to do with calories”? well that is a good question and quite simply answered, calories are the basic fuel units that your energy systems rely on to make your muscles  move. When any of the four energy systems need to reproduce the ATP for muscle contraction, they do so by taking calories and converting them.