While most individuals know that aerobic exercise is good for the heart as well as that resistance training helps to build lean body mass, most individuals don’t fully comprehend how these different types of exercise cause very diverse responses within our bodies. A simple understanding of how our body uses energy during different forms of exercise is critical for designing an effective exercise programme.
Energy is needed for all types of bodily processes such as growth and development, repair, the transportation of various substances between cells and, of course, muscle contraction. Whether it’s during a 26-mile marathon or one explosive movement like a tennis serve, skeletal muscle is powered by one and only compound: adenosine triphosphate (ATP). Nevertheless, the body stores only a small quantity of this energy currency within the cells which is sufficient to power just a few seconds of all-out exercise. This means that the body must replace or resynthesise ATP on an ongoing basis.
During fitness training and exercise, we are concerned about the transfer of chemical energy into mechanical energy. In this procedure, the breaking of chemical bonds in molecules will free up energy for use by the body. A great example of this transfer of energy is that of a football player who converts chemicals in the body (which come from food) into mechanical work, for instance jumping in order to take a mark.
Heat energy is also released in this move which is the reason why a person feels warm after they’ve been jogging for a short time. The body does not use the energy directly that is released in the breakdown of food. Rather, the energy is used to make ATP. Only when this energy is released from the breakdown of this compound can the cell perform its specialised function. This specialised function is dependent on the cell type. For example, cells in the intestine have a digestive function.
Adenosine triphosphate explained
ATP is an energy-rich compound that is found within the cells of the body. It’s almost always the source of energy fo the reactions that take place in the body – especially for muscle contraction which leads to almost every movement.
ATP is composed of a smaller compound (adenosine) as well as three chained phosphate groups. The final phosphate group is held onto the chain with a high-energy bond. A lot of energy is released when this bond is broken which provides the energy that powers the human body. It provides energy for all the processes, from breathing and digestion right through to muscular movements. When ATP is broken down it frees up energy. ATP is further broken down into adenosine diphosphate (ADP) – in other words adenosine plus two phosphates – and a separate phosphate group.
Food supplies the source for ATP. Fuels which are stored, such as carbohydrates and fats, are not modified into ATP. A portion of the energy which is released when these food chemicals break down triggers the joining together of molecules to form ATP.
The body has a number of ways of providing energy during exercise. Depending on the intensity and/or duration of activity the body can supply energy through aerobic or, alternatively, anaerobic metabolism. The three energy systems in this framework are the ATP-PC System (instant energy), the Glycolytic system (short-term energy), and the Oxidative system (long-term energy).
Each has a certain means of providing energy depending on what the body requirements.