The short-term effects of exercise have been well documented. For example, physical activity is known to galvanize the production of brain chemicals that promote happiness and a sense of well-being. But these effects are short-lived. In recent years, science has shed more light on the long-term implications of intense exercise, which can be hard to study, and both positive and negative aspects are now known to occur; for a large part, however, exercise is a positive force. Consult your doctor before beginning any new exercise regimen.
Cardiovascular Effects
Regular participation in exercise confers multiple benefits upon the cardiovascular system, including a stronger resting heart rate, which may decrease by as many as five to 25 beats per minute, and the efficient utilization of oxygen in aerobic respiration, University of New Mexico researcher Dr. Len Kravitz writes. Exercise also has a strong effect upon cardiovascular anatomy. It creates stronger cardiac muscles, more red blood cells, elastic arterial walls and denser capillary beds to exchange gases in the lungs. Many of these factors, by affecting blood pressure and the responsiveness of the heart rate to exercise, also predict the state of the cardiovascular system and overall mortality over time.
Body Composition
Exercise has an acute effect upon body composition. Muscles, bones and ligaments all become stronger to cope with the additional stresses of high-intensity exercise. An increased number of mitochondria, the powerhouse of the cells, means an increase in the rate of energy production, the Teach PE website explains. More myoglobin within muscles allows oxygen to be stored and moved in bulk. Enzymes involved in energy production become more concentrated and efficient to aid in metabolism. And with a parallel change in diet, exercise can cause a reduction in total body-fat percentage.
Cancer and Cell Growth
The National Cancer Institute cites multiple studies suggesting that exercise reduces the risk of many types of cancer, including colon and lung, depending upon the intensity, duration and frequency of the exercise. The magnitude of the protective effects are greatest among those who participate in high-intensity activities. The precise mechanism isn't quite known as of 2011, but it is believed to be related to the way in which exercise influences energy balance, hormone metabolism, immune factors, insulin regulation and the length of tissue's exposure to carcinogens. In addition, exercise is believed to activate special proteins known as cytokines that promote cell growth and repair, both of which affect aging. These effects appear to be long-term, but the exercise must be consistent.
Osteoarthritis
On the negative side, high-impact exercises have been implicated in the long-term development of osteoarthritis, a type of condition caused by the degradation of cartilage in the joints that connect together bones in the knees and hips. Running, tennis, weightlifting, soccer, football and rugby have all been known to have this effect. The development of osteoarthritis in runners, particularly, has been linked to the amount and rate of mileage run. The choice of terrain and running form also matter. This primarily affects athletes but may also affect non-athletes if the exercise is performed at very high intensity over long periods of time. For the most part, however, moderate recreational exercise can actually reduce the risk and intensity of osteoarthritis.
References
- University of New Mexico; Exploring the Mysteries of Exercise; Len Kravitz, Ph.D.
- Teach PE: Long-Term Effects of Exercise
- National Cancer Institute: Physical Activity and Cancer
- "U.S. News and World Report" magazine; Vigorous Exercise Can Really Roll Back the Years; Christine Larson; Jan. 31, 2008
- Arthritis M.D.; The Role of Sports and Activity in Osteoarthritis; Abigail E.L. Chambers and Grant Cooper, M.D.; 2005
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