So what do we mean by fuel utilisation? What does our body burn during exercise?

This depends upon the types of fuel our body is using during different types of exercise and while we are resting. In order to differentiate between the two we must firstly understand what we mean by aerobic exercise and anaerobic exercise. There are basically two types of exercise performed by the body:Anaerobic and Aerobic.

It is important to note that it is not the exercise that determines whether it is anaerobic or aerobic but the energy system that provides the fuel.

Carbohydrates (CHO) and Exercise Performance

Any form of anaerobic exercise can only be performed if a Carbohydrate energy source is available. Only Carbohydrate can be broken down anaerobically to maintain the supply of energy to the contracting muscle fibres. The process is known as anaerobic glycolysis and results ultimately in the production of lactic acid.

Generally speaking as exercise intensity increases there is an increase in the use of CHO as an energy source. (see fig 1. below) The disadvantage in their use is that their store is limited when compared to fat and the depletion of muscle glycogen stores leads rapidly to muscular fatigue.

As you can see from Fig 1. , exercise intensity is directly related to your heart rate shown as beats per minute (Bpm). The higher the intensity the more carbohydrates the body needs The longer the exercise the less carbohydrate available The longer the exercise intensity the greater the supply of energy comes from fat (be careful: see Table 1 below) The longer the exercise duration the increase in protein as an energy source.

The table below shows how the levels of exercise (in relation to heart rate) effect the fuel used by the body. In the early 90s many people fell into the trap (started in the US) that walking burned more fat calories than any other form of exercise and from this table above that would also appear to be true. When you walk 60% of your calories come from fat. It is also true that while the body is at rest, you also burn more calories from fat, so why don't you just sit and watch TV and lose weight. If only it were that easy! If we now take a look at row 2, jogging at 6 mph we can see that we burn far more calories than if we were walking and even though we are only burning 40% fat we are in fact burning more calories from fat. Now we are not saying that walking is a poor form of exercise, far from it, but if you wish to burn calories and fat faster you need to push yourself that little bit harder.

Fuel Utilisation - Overview

Looks at how the body assimilates the foods that you ingest and converts them into energy for use by the body during rest and exercise. It will show you how the different food types have a direct impact on your metabolism and your energy levels whether you participate in an exercise program or not. It will also look at how different food types are used for different types of exercise and how these can be used to increase energy or aid weight loss as part of an exercise program.

Q. So how does what we eat reflect our energy levels during rest and exercise?

CHO And Exercise Performance

Any form of anaerobic exercise can only be performed if a Carbohydrate energy source is available. Only Carbohydrate can be broken down anaerobically to maintain the supply of energy to the contracting muscle fibres. The process is known as anaerobic glycolysis and results ultimately in the production of lactic acid. Generally speaking as exercise intensity increases there is an increase in the use of CHO as an energy source. The disadvantage in their use is that their store is limited when compared to fat and the depletion of muscle glycogen stores leads rapidly to muscular fatigue.