Knowing the energy systems

The human body uses three primary energy systems to fuel its activities: the phosphagen system, the glycolytic system, and the aerobic system. Each system provides energy to different degrees depending on the intensity and duration of the activity being performed. Understanding these energy systems is important for athletes and fitness enthusiasts who want to improve their performance and achieve their goals.

The first energy system is the phosphagen system, which provides energy for short, high-intensity activities that last up to 10 seconds. This system relies on stored creatine phosphate in the muscles, which is rapidly broken down to produce adenosine triphosphate (ATP), the primary energy source for muscle contractions. Activities that primarily use the phosphagen system include weightlifting, sprinting, and jumping.

The glycolytic system is the second energy system, which provides energy for activities lasting 30 seconds to 2 minutes at high intensity. This system relies on glucose, which is stored in the muscles as glycogen or taken up from the bloodstream. Glucose is broken down through a process called glycolysis to produce ATP. However, this system produces lactic acid as a byproduct, which can lead to fatigue and a burning sensation in the muscles. Activities that primarily use the glycolytic system include high-intensity interval training (HIIT), soccer, and basketball.

The third and final energy system is the aerobic system, which provides energy for activities lasting more than 2 minutes at moderate to low intensity. This system relies on oxygen to break down glucose and fatty acids to produce ATP. The aerobic system is the most efficient energy system because it can produce ATP for long periods of time without causing fatigue or muscle damage. Activities that primarily use the aerobic system include distance running, cycling, and swimming.

Understanding the energy systems of the body is important for athletes and fitness enthusiasts to optimize their training and performance. For example, athletes who primarily rely on the phosphagen system, such as weightlifters and sprinters, would benefit from short, high-intensity workouts to improve their performance. Athletes who primarily rely on the glycolytic system, such as soccer and basketball players, would benefit from HIIT workouts to improve their endurance and recovery time. Athletes who primarily rely on the aerobic system, such as distance runners and cyclists, would benefit from endurance training to improve their cardiovascular fitness and endurance.

There are benefits to train outside your main energy system if you are an athlete or general population. For example, basketball players need to train explosively for jumping power. This would probably be done in the phosphagen system even though they primarily stay in the glycolytic system for games.

Use these energy systems as a general rule, but don’t be so dogmatic that you never train outside a certain system. This information can be used to help make a more pragmatic training program for you and your specific goals.