Energy metabolism encompasses the reactions taken by the body that turn the food you eat into energy. This energy is stored in the form of adenosine triphosphate or ATP. A small amount of ATP is stored within the muscles so when more is necessary there are three main pathways utilized for its production: ATP/CP pathway, and Glycolytic and Oxidative pathways. Each one uses a different way to create ATP. The Glycolytic pathway breaks down glucose for energy during anaerobic exercise.
ATP/CP Pathway
The initial shot of energy used by the body when performing an explosive exercise takes the energy from the ATP/CP pathway. Anaerobic exercises that require all out intensity for a very short time fulfill their energy needs here. This energy store is good for roughly 10 seconds. This is the main pathway for activities such as pitching, shot putting and powerlifting.
Glycolytic Pathway
The Glycolytic pathway is also anaerobic so oxygen is not necessary for energy use. After depletion of the ATP/CP pathway the body then calls on the Glycolytic pathway. This is where carbohydrates are broken down to eventually make energy. The conversion of blood glucose into energy leaves lactic acid behind as a waste product. The build up of this waste is what leads to muscle fatigue. This pathway produces enough energy to last for one to two minutes.
Oxidative Pathway
The Oxidative pathway is the only aerobic energy supply, meaning oxygen is involved. Energy production occurs when the lactic acid left over from the Glycolytic pathway combines with oxygen. This pathway is good for endurance events and all low-intensity, long term activities.
Glucose in the Muscles
There are two types of muscle fibers, each associated with certain energy pathways. Primarily used during aerobic exercise, slow twitch fibers get their energy through the oxidative pathway. Fast twitch fibers correlate to size, power and strength and employ the ATP/CP and glycolytic pathways. These fibers are set up to quickly get glucose turned into energy.
References
- "Fitness: The Complete Guide"; Fredericdk C Hatfield PhD; 2008
- "Nutrition: The Complete Guide"; John Berardi PhD, Ryan Andrews MS/MA, RD; 2009
