The Importance of Exercise

The cardiovascular system primarily consists of the heart, blood vessels, and lungs. It incorporates the systemic circulation that runs through the rest of the body to provide oxygenated blood. During exercise, the circulatory system attempts to be economical in delivering nutrients such as oxygen to the muscles. This is accomplished by the expansion of blood vessels and capillaries in the muscles that are being worked while exercising. Similarly, capillaries and blood vessels of the parts of the body that are not being used during exercise are restricted. This process maximizes delivery of nutrients to areas of the body such as legs, arms, and the heart, while this process minimizes delivery of blood and nutrients to muscles not being used during exercise such as the digestive tract. The cardiovascular system also regulates heat by expanding capillaries close to the skin’s surface, allowing the body to cool itself during exercise.

A byproduct of energy production in the body’s muscles is the creation of carbon dioxide (CO2) as the skeletal muscles use oxygen to produce energy. The concentration of carbon dioxide within the blood increases dramatically during exercise as does the demand for oxygen. This combination of events causes the heart to contract and expand more frequently and with greater force than when the body is at rest. This increase in heart rate insures delivery of oxygen to the body’s extremities. It also accelerates the removal of waste products from the body’s tissues. These waste products are filtered by the kidneys and liver as the blood returns to the heart.

The respiratory system primarily consists of the nose, mouth, lungs, and air passages. The two major functions are to provide oxygen and to eliminate carbon dioxide from body tissues. During exercise, the process known as pulmonary ventilation increases proportionately in direct response to the intensity of the exercise. This activity is measured and expressed in terms of liters per minute (L/min). Pulmonary ventilation consists of tidal volume and respiration rate. Tidal volume is the quantity of air inhaled and exhaled. Respiration rate refers to the number of times per minute a person inhales and exhales. During a period of intense exercise, breathing rates can increase from a typical at rest rate of 15 respirations per minute to as many as 50 respirations per minute. When exercise is continuous, the volume of oxygen required will increase as the muscles being exercised increase their demand for oxygen. However, there is a limit to how much oxygen a person’s body can intake at any time. This is known as VO2 max. During the period of VO2 max, the muscles can consume more oxygen than the pulmonary system can replace. People who have lead a sedentary lifestyle can reach this maximum period in an extremely short period of time which leads to fatigue and lack of energy. On the other hand, someone who does aerobic exercises 20-30 minutes per day has greater cardiopulmonary capacity; therefore even at VO2 max exercise can be maintained for an extended period of time.

The Cardiopulmonary system’s response to exercise programs over a period of time tends to increase ones overall health. One of the heart’s positive responses to extended exercise is the increase of muscle mass and improved efficiency. Regular exercise increases the heart’s cardiac output. The cardiac output is a combination of the heart beat per minute times the stroke volume. The stroke volume is the amount of blood expelled from the ventricles during cardiac contraction. Exercise increases the efficiency of the heart muscle, therefore increasing the amount of blood the heart delivers to the body upon each beat of the heart. People who exercise regularly tend to have lower resting heart rates and they are able to more quickly recover from a period of an extended VO2 max.

The New England Journal of Medicine in 2008 reports that a heart’s muscle mass can decrease by 15 percent after 12 weeks of being bedridden, and as much as 25 percent for a person who is permanently bedridden due to spinal cord injuries. A reduction in cardiac muscle mass along with immobility can create a continuously inadequate blood flow to the extremities, including the brain. When a healthy person moves from a laying down position to a standing position, the sensors in the carotid arteries and the sensors in the aorta automatically regulate blood pressure throughout the body by forcing blood back to the heart from the extremities. People who are bedridden tend to lose this ability and over extended periods of bed rest, a person may permanently lose this natural function and become orthostatic intolerant.

I would recommend to my neighbor who is beginning an exercise program after leading a sedentary lifestyle to begin this program under a doctor’s orders. I would also encourage him to pay attention to his body’s responses to the exercise program such as rapid heartbeat, shortness of breath, chest pains, and/or fatigue. He should ask his doctor what body measurements he needs to chart such as his resting heart beat, his heart rate during maximum exercise, and his heart rate recovery time after exercise. After a few months, he could compare these charted results to track his progress. Exercise is something the body benefits from over a prolonged period of time. He should not expect dramatic results right away. He should start slowly with exercise such as walking, gradually building up from maybe 10 minutes per day until he builds up to 60 minutes per day.




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