The Scoop on Energy Systems

                The cardiovascular system is responsible for delivering oxygen to the body’s tissues. It works in conjunction with the circulatory and respiratory systems and is comprised of three separate energy systems.  Each is designed to perform a specific task but are interwoven together to complete tasks such as sprinting, jogging and jumping.  There are two primary forms of energy, anaerobic and aerobic. These energy systems utilize a form of energy called adenosine triphosphate or ATP, which is produced by the body from food. ATP allows muscle function and in turn movement to take place.

                The anaerobic energy system can be broken into two sub categories, the creatine phosphate (CP) and anaerobic glycolysis. These energy systems function in the absence of oxygen which places the body’s tissues in an oxygen depleted state that must be repaid. These systems operate under very extreme intensities when the body is unable to keep up with its oxygen requirements placed upon it; this is called the anaerobic threshold or lactate threshold. This energy system relies primarily on glucose or glycogen as a fuel source (broken down carbohydrates) which is one of the reasons our diets must contain carbohydrates. When anaerobic metabolism takes place due to the lack of oxygen it produces several byproducts that conflict with body’s ability to function. When enough of these byproducts are produced muscle function is inhibited and eventually movement is impaired. Let’s take a closer look at the two energy sub systems that make up the anaerobic system.

                The CP system is responsible for immediate energy requirements such as short sprints and jumping. It can create ATP almost immediately but only for a limited time. It is the primary energy system during maximal effort activity for the first 10 seconds. It is extremely important for most ball sports, all types of resistance training and Olympic lifting. Unlike anaerobic glycolysis this system functions utilizing creatine phosphate. You might have heard of the supplement creatine which has been widely used as an ergogenic aid during weight lifting. The supplement creatine is a man made version of what your body uses during activation of the CP system. The basis behind creatine supplementation is increasing the creatine stores in the body which will result in the ability to utilize the CP system for maximal effort activity such as resistance training or jumping.

                Our next energy system, anaerobic glycolysis is the primary energy system during activities such as long and multiple sprints. It is much like the CP system producing energy at a very quick rate and also generating byproducts due to the absence of oxygen which eventually inhibits muscle function and movement. Anaerobic glycolysis creates ATP through the metabolism of glucose and glycogen and is the primary energy producing system between 30 seconds and three minutes of continuous maximal effort activity. It is also extremely important for most ball sports due to a number of variables (lack of rest, lack of intensity, etc.). It is also important for short to mid distance running.

                The aerobic system takes over after three minutes of continuous or non maximal activity. It is able to metabolize fats and carbohydrates for ATP creation. Unlike the prior two energy systems it utilizes oxygen to produce ATP which means it doesn’t create movement impairing byproducts. This is the energy system that is responsible for long distance runs. It is also important for most ball sports because it is responsible for breaking down the byproducts during recovery and rest. When most fitness professionals think of aerobic work they instantly confuse this with long slow distance runs that have been linked to causing decreases in power. Aerobic capacity or commonly referred to as work capacity is important for recovery both during activity and as a way to facilitate blood flow through tissues. Imagine a basketball player sprinting back and forth on a court for two and a half minutes. This athlete would be utilizing the CP system for maximal effort movements such as quick cuts and jumps and utilizing anaerobic glycolysis to get up and down the court. As discussed above this athlete’s body would be generating byproducts that are slowly decreasing his ability to produce force optimally and causing fatigue. The coach notices that the athlete has become sluggish and finally gives him some time to rest and recover, the aerobic system kicks in and begins breaking down the byproducts and returns the athlete back to an optimal performance level.  Let’s take the same athlete again, he has just completed a demanding away game against a rival opponent. Utilizing aerobic conditioning such as tempo runs can help facilitate blood flow through the muscles that were used in the event. This increased blood flow will help with the tissue rebuilding process (remember tissues must break down and rebuild to adapt to added and new stresses).

                Each and every energy system has a specific and secondary task, whether that be fueling the muscles for explosive powerful movements or helping the body recover from a task. These three energy systems are interwoven and must all be accounted for when training athletes to optimize performance.