Bodybuilders train their muscles, but they often neglect the most important muscle of them all - the heart. Your heart is a great indicator of your level of fitness. Training your heart can improve all aspects of your health. Your heart can even be used as a guide to help improve your training and, more importantly, customize training to your body. When you understand how the heart works and how it can be used as an amazing tool for training, you will appreciate exactly how much the heart matters!

The average resting heart rate for an adult is around 72 beats per minute, or 75 for women and 70 for men so why even worry about your heart rate? Heart rate is a great indicator of training. In order to better understand heart rate, you must understand the various "systems" of energy that your body uses when you train. There are three systems that are always in effect, but one system will dominate based on the type of training. These systems are ATP-CP and glycolytic (both are anaerobic, or systems that do not rely on oxygen as the primary energy source) and aerobic.

The ATP-CP system is the system that bodybuilders are most familiar with. It is the system where your body is forced to perform work without the aid of oxygen. When you perform a repetition during a weight training exercise, your muscles contract and must generate force quickly to resist the weight. This action happens quickly, and your body is not able to use oxygen to fuel the contraction. Instead, your body will rely on stores of energy within the muscle cells, namely a compound called adenosine triphosphate (ATP) and creatine phosphate. ATP depletes rapidly, and is replenished by CP. Sports that rely on this system include power lifting, shot put, and short distance sprints.

Bouts of work lasting more than a few seconds will draw energy mainly from the glycolytic system. Once ATP and CP are depleted, the glycolytic system kicks in. This system takes carbohydrate stored in the muscle cell (glycogen) and breaks down the glycogen to replenish ATP. Sports that utilize the glycolytic system include mid-distance sprinting, basketball, volleyball, boxing, and football. These are all sports that involve prolonged periods of moderate activity mixed with short bouts of near maximal effort. Marathon runners and other distance runners use the aerobic system. The aerobic system utilizes oxygen for energy. The blood transports oxygen, so this system has the largest influence on the heart.

Any type of activity that is prolonged (more than a few minutes) and does not involve repeated bouts of near maximal effort would use the aerobic system as the primary source of energy. Keep in mind that all systems are being used, but the aerobic system becomes the predominant system.

The common breakdown of these training zones is:

50% - 60% = low intensity
60% - 70% = fat-burning zone
70% - 80% = aerobic zone
80% - 90% = anaerobic zone
90% - 100% = maximal zone

*This was taken from sites and thought I should add it just for information purposes. I see a lot of people leaving the heart out of there training which is very disappointing. Hope that this information provided will infulence people to work in there heart towards there training.