Exactly how does cardiorespiratory endurance exercise improve your physical health? First, it makes your heart, lungs, and blood vessels work hard. Your body responds by adapting; that is, it becomes able to accommodate future training demands with less or no stress. In time, the muscles involved develop a more extensive network of blood vessels, so that your blood has more available routes for oxygen transport.
The body develops more red blood cells (which carry oxygen) and a greater volume of blood. Furthermore, is typically in increase in the amount of air the lungs can take in and breathe out at one time (the vital capacity) and an increase in the amount of air the lungs can take in over a period of time (the maximum breathing capacity). And the exchange of oxygen and carbon dioxide in the tiny chambers (alveoli) of the lungs becomes more efficient.
Effects on The Heart
With training, your heart becomes stronger and more efficient. Though the heart does not increase much in actual size, it pumps an increased amount of blood on each beat and is emptied more completely each time. Between beats, it can slow down and rest more : The normal adult resting pulse rate is around seventy beats per minute, and eighty to ninety beats is not unusual in sedentary individuals. In contrast, the physically fit adult usually has resting pulse rates of only fifty-five to sixty beats per minute. (The pulse may be even lower sometimes : In trained athletes, such as runners, it is not unusual to see rates of forty beats per minutes). Consequently, the heart makes thousands fewer beats per day, which reduces wear and tear on heart valves and blood vessels.
Others Effects
Endurance exercise may also reduce some forms of hypertension (high blood pressure): It tends to relax the tiny arteries (arterioles) that work much like nozzles in controlling blood pressure. Further, experts believe that endurance exercise increases the ratio of high-density lipoprotein (HDL) to low-density lipoprotein (LDL) in the blood: Higher ratios of HDL to LDL are associated with a lower risk of heart disease.
Last but not least, endurance exercise burns calories, thus contributing to weight control. Research shows that in typical adult conditioning programs-involving twenty-minute sessions three days a week-partially trained participants expending energy at about 400 calories per session can lose about seventeen pounds a year if their calorie intake remains constant.
References :
Jack H. Wilmore, Training for Sport and Activity: The Physiological Basis of the Conditioning Process, 2nd ed, Boston : Allyn & Bacon, 1982.
Philip L. Hooper and R. Philip Eaton, “Exercise, High Density Lipoprotein and Coronary Artery Disease”, in O. Appenzeller and R. Atkinson, eds, Health Aspects of Endurance Training, Encyclopedia of Medicine and Sport, Vol. 12, Basel, Switzerland : S. Karger, 1978.
M. Pollack, J.H. Wilmore, and S. Fox, Health and Fitness Through Physical Activity, New York: Wiley, 1978.
