Newsletter February 2013
General Wellbeing - The energy systems in the body
What I thought I would discuss this month, is how the body works in terms of energy. We all know that we need to eat to survive, as the food provides us with the nutrients, vitamins and calories needed to maintain our health. What I find is less common knowledge with my clients, are the three different energy storage systems in the body; and depending on either your sport, or lifestyle this could influence what you eat. Now it's worth mentioning at this point that I'm not a qualified nutritionalist, however, if once you've read this article you'd like to speak to someone there are plenty of qualified people (Shelley Kirkup http://www.circleofhealthnutrition.co.uk/contact.html is a local nutritionalist in the Wilton/Salisbury area). Another thing to consider is that, you are not 'what you eat', you are in fact 'what your body can absorb'; I'm sure anyone with food intolerances, or allergies will testify to the validity of this statement.
So back to the body's three energy systems, firstly the 'fuel' for the muscles is a naturally produced substance in the body called adenosine triphosphate (ATP). To generate the energy from the fuel, the body uses a chemical reaction to break down ATP into adenosine diphosphate (ADP). All 3 energy systems work seamlessly to use, or promote the creation of ATP.
System 1
This system is called the phosphagen system. It utilises the ATP and another substance called creatine phosphate (CP), naturally stored within the muscles to generate energy. This system doesn't require oxygen to function and is therefore anaerobic. It powers your muscles for around 10 seconds of exercise before being depleted.
System 2
Is the glycogen-lactic acid system. This is where the body starts to break down glycogen (a form of glucose) already stored in the muscle to continue producing ATP. The by-product of this system is lactic acid, which produces the stinging / burning sensation in the muscles whilst exercising. It is also anaerobic and powers the muscle activity from 10 seconds to 2-3 minutes.
System 3
The 3rd system is the aerobic system and uses oxygen to burn the remaining glycogen stores, in conjunction with fat, to create ATP. This powers the body beyond the 2-3 minutes of system 2, and works until fatigue sets in and we cannot continue.
During prolonged exercise the body will burn the majority of this glycogen store in advance of utilising any fat stores. Usually an adult has enough glycogen in their body to power 20 minutes of intense exercise, after that the body starts using more and more fat stores as a replacement.
The role of carbohydrates and body weight
When we eat carbohydrates the body converts them into glycogen and replenishes the body's natural store. The inference then, is that a smaller carbohydrate intake will lead to a smaller store of glycogen and therefore greater fat burning potential. It is not to say that removing carbohydrates all together is a good thing, however, a little moderation may help. The other important thing to note here, from a dietary perspective, is that once your glycogen store is replenished, any excess carbohydrates are turned to fat instead.
In summary
I hope this brief foray into the world of energy systems and nutrition will have provided you with a greater insight into how our bodies work. However, there is so much more detail to it than this article can ever hope to provide, and any changes you make to your diet should be healthy and sustainable. Otherwise there is no long term gain and your general wellbeing may become compromised, so please seek professional advice before making any changes!