Energy System Development
This blog was contributed by Joseph Ratti, Sports Performance Coordinator at Bon Secours In Motion at Healthy Way in Virginia Beach. 
Energy System Development (ESD) is a training method that aims to increase the efficiency of energy metabolism to improve your athletic performance. To accurately prescribe ESD, it is important to know the energy demands of your sport as well as your baseline levels of energy metabolism. For example, football involves multiple explosive and short duration events, followed by an ample rest period. After a base level of conditioning is present, the majority of ESD should be geared towards improving repeat sprint ability. A VO₂ Max Test will measure the maximal amount of oxygen the body can uptake and utilize during exercise. After identifying each athlete’s peak VO₂ and anaerobic threshold, strength and performance coaches can accurately prescribe training programs.
There are three main energy systems used to fuel the human body during exercise: phosphagen, glycolytic, and aerobic systems.
Phosphagen
The phosphagen system is your immediate or shortest duration energy system, lasting roughly no longer than 10 seconds. The phosphagen system is used in sports like football, baseball, and short sprints. It basically uses the ATP stored directly in your muscles to produce energy quickly. After about 10-12 seconds, the body starts utilizing simple carbohydrates or glucose as a fuel source, rather than ATP.
Glycolytic
The glycolytic system requires the chemical breakdown of sugars in the body to fuel muscles for activity. Training this system leads to a better utilization of glucose and a greater duration of exercise at a higher intensity. This system is predominantly used in power sports like soccer, basketball, hockey, rugby, and 200 meter, 400 meter, and 800 meter track events.
Aerobic
The aerobic system begins to be utilized for medium intensity activities and utilizes oxygen to fuel the body. Unlike the anaerobic pathways, training your aerobic system yields little improvements in speed, power or strength and actually leads to a degradation of muscle tissue, the latter of which we know improves body composition and increases basal metabolic rate.
When beginning a training program at In Motion Sports Performance a program is designed to your specific needs. Each energy system development program is a periodized conditioning plan designed to match the metabolic and movement demands of an athlete’s sport.