Anaerobic aerobic amino acids carbohydrate loading carbohydrates muscle glycogen creatine phosphate adenosine triphosphate fat cardiorespiratory exercise, also known as exercise, uses oxygen and typically involves using large aerobic muscle groups during continuous activities. your body produces energy under conditions during the first few seconds of intense exercise. when one of the three phosphates is removed from, adp is formed and energy is released. is stored in the muscles and is broken down to replenish atp stores. when participating in low-intensity activities over a long period of time, the body primarily uses for energy. a small amount of from protein can be utilized for energy production during endurance events, but their primary role is to promote muscle growth and with repair. your body burns for energy during every type of exercise that lasts longer than 3 sec. intensity and duration of exercise will affect the percentage of energy that is derived from this source. endurance athletes may use a training strategy known as to maximize their body's glycogen stores. the body's preferred carbohydrate source during very high intensity exercise for energy is