Despite all the fancy color-coded charts that coaches use to indicate the various energy systems it is virtually impossible to train and isolate an energy system. It is important to remember that the energy systems are intensity dependent, not time dependent. The body must produce ATP for muscle action to occur and ATP can be manufactured both through aerobic and anaerobic means. All the energy systems work together synergistically. They do not switch on and off based on the duration of the effort. Therefore think of a training emphasis, but stop deluding yourself by thinking energy systems. Intensity of the work determines the energetic demands, remember all systems of the body cardiovascular, neural, muscular, endocrine hormonal, and immune systems all work together to allow the body to meet the demands of training and competition. There are no switches that turn on or off, all systems coordinate and cooperate to solve the movement problems presented to the body. Achieving peak fitness relative to the activity you are training for depends on how efficiently you get all the systems working together. Get beyond energy systems and train the body for the rigors of the competition.