Aerobic and Anaerobic
There are basically two types of energy systems that the body utilizes, Aerobic and Anaerobic. Each energy system produces Adenosine Triphosphate (ATP), which is used by the muscles to contract.
The Aerobic System
The Aerobic System can utilize carbohydrates, proteins or fat to supply an unlimited amount of ATP as long as oxygen is present. The Aerobic system provides medium to very long-duration energy production with low to moderate power (less than 85% of maximum output). The by-product of this system is heat, water, and carbon dioxide.
The Anaerobic System
The Anaerobic System can only utilize carbohydrates for ATP production. This system does not use oxygen in the metabolization of its fuel source. The Anaerobic System provides a short duration (45 – 70 seconds) and high power. The by-product of the metabolization of glucose (glycolysis) in this system is heat and lactic acid, the cause of muscle soreness immediately after exercise. Muscle soreness 24 to 48 hours after exercise is due to torn muscle fibers and connective tissue. This type of soreness can be reduced by an adequate warm-up and cool-down stretching exercises. (Aerobic and Anaerobic)
Aerobic capacity is the ability of the body to collect and transfer oxygen from the air through the lungs and blood to the working muscles. This is related to cardio-respiratory endurance and is referred to as Maximal Oxygen Consumption or VO2 max. Aerobic Capacity reduces at about 10% per decade after 30 years of age.
The Anaerobic Threshold is defined as that point where the body can no longer meet the oxygen demand and its anaerobic metabolism is accelerated. This point varies on an individual basis and is dependent on the fitness level. For healthy individuals, this occurs between 50% and 66% of their maximal working capacity. This would be equivalent to running faster than half speed.
Cardiovascular and Respiratory System
Air is inhaled into the lungs where oxygen is exchanged through tiny gas permeable sacs within the lungs for carbon dioxide from the blood. The heart pumps the oxygen-rich blood from the left atrium through the arteries then through tiny vessels called capillaries to the tissues of the body. At the cell level, oxygen is given up for metabolism and the carbon dioxide produced by this action is picked up by the blood. The oxygen-depleted and carbon dioxide-rich blood is then pumped back to the heart, through the veins to the right atrium to the lungs where the process is repeated.
Aerobic activity increases the strength of the heart muscle. The result is a greater volume of blood per stroke. This is referred to as the Stroke Volume or the amount of blood ejected from each ventricle of the heart during one stroke. Cardiac Output is a measure of the amount of blood pumped through each ventricle in one minute. Vital Capacity is the volume of air that can be forcibly ejected from the lungs in a single expiration. The aerobic activity provides a Training Effect on Vital Capacity, Stroke Volume, and Cardiac Output. By definition, an artery carries blood away from the heart while veins carry blood toward the heart.
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