Energy Systems

It is important to understand that in order to accomplish work (i.e., physical training), the body requires energy. This energy is derived from the food we consume. It is digested and broken down into its basic nutrients which are then converted into sugar or fat and used as energy. Two major energy systems (aerobic and anaerobic) are used to deliver fuel to the working muscles. The system or pathway used to deliver the energy is determined by the type (intensity and duration) of the work required by the body.

1. Anaerobic Energy System: There are two primary anaerobic energy sources and both are limited by the amount of stored energy available. These are known as the ATP-PCr system(anaerobic alactic) and the Glycolytic system (anaerobic lactic).

 • ATP-PCr Source: is a high powered system that is used for short term, high intensity activity, typically lasting no more than 10-12 seconds. Applying hand cuffs or running up a flight of stairs, are examples of activities that would primarily utilize the ATP-PCr system.

• Glycolytic Source: is another high powered energy producer that can sustain high intensity activity. The by-products of this system are pyruvic acid and lactic acid. These products can affect muscle contraction and cause fatigue. This system is used predominantly in activities lasting between 15-120 seconds, and is one of the dominant energy systems in fighting, short chases, and moving from cover to cover.

 2. Aerobic Energy System: provides energy for lower intensity activity. It contributes the majority of the energy we use to function throughout the day and is also the main contributor for long term physical activity such as long distance running or following a dog handler on a track. The aerobic system also plays a crucial role in assisting with recovery in between anaerobic exertion.

 It’s important to note that none of these pathways work in isolation. Rather they all contribute a portion of energy and their relative contribution will depend on the duration and intensity of work. The type of work involved with PARE can tax one or all of the energy systems used in the body. The Strength and Conditioning Program is designed to train all of these energy systems.