| -Integrative Arts- Exercise published in the Mayo Clinic Health Letter, June 1994 Are the risks underplayed and the benefits overdone? You're established, comfortable in your career or retirement…and sedentary. Too busy to fit regular exercise into your schedule, you make up for it with a vigorous workout once in a while. It's better than no exercise at all, right? Probably not. Exercise clearly lowers your risk of heart disease if you do it regularly and in moderation. But new evidence suggests that if you're out of shape, occasional strenuous physical exertion, such as shoveling snow or running, is risky. Risks stem from overdoing it New data from a Harvard study show heart attack risk among sedentary people was more than 100 times greater during strenuous exertion than during light or no exercise. Researchers theorize that heavy exercise may trigger disruption of plaque, causing formation of a blood clot that can block coronary arteries. The risk seems to be greater in people not used to vigorous exercise. Being in shape, however, may lower your risk. The study found increasing the frequency of activity led to a progressively lower risk of heart attack. In people who regularly exercised at least 5 times a week, heart attack risk was only 2.4 times greater during strenuous exertion than during light or no exercise. But here's an important perspective: Most heart attacks don't occur during exercise (see "Risk of heart attack during exertion vs. rest"). Of all heart attacks, 96 percent occur at rest. The minority of heart attack - only 4 percent - occur during strenuous exertion. Most people who have attacks during activity are sedentary or have underlying heart disease and overdo it. Benefits of regular exercise If you exercise regularly, your overall risk of a heart attack is about half that of those who are sedentary and out of shape. Regular exercise (about 3 to 4 times a week) reduces risk of death from all causes, including cardiovascular disease and cancer, by about 70 percent. With routine exercise, you may reacha level of physical fitness comparable to an inactive person 10 to 20 years younger. Regular exercise may also help you live longer by benefiting all systems of your body: Heart - Exercise increases your heart's ability to pump blood and decreases your resting heart rate. Your heart can pump more blood with less effort. Exercise increases the size of your coronary arteries and reduces clogging due to arteriosclerosis. Some studies show exercise promotes development of new arteries if your existing arteries are partially blocked by deposits of cholesterol and blood fats. Exercise also increases the efficiency of your blood's oxygen-carrying capacity and your muscles' uptake of oxygen. If you exercise regularly, you'll have fewer abnormal heart rhythms (arrhythmias) and be able to exercise longer and more intensely before developing angina, a signal of too much exertion. Exercise can also reduce your blood's tendency to form clots. Cholesterol - Exercise increases levels of high-density lipoprotein (good) cholesterol and decreases low-density and very low-density lipoprotein (bad) cholesterol and triglyceride levels. Favorable changes in cholesterol levels translate into as much as a 30 percent reduction in risk of coronary artery disease after 6 to 12 months of regular, moderate exercise. Blood Pressure - Exercise can lower blood pressure (2 to 5 mm Hg) and is especially helpful if you have mild hypertension. Regular exercise can prevent as well as reduce high blood pressure. Diabetes - If you have non-insulin dependent diabetes, exercise can reduce the level of your blood sugar (glucose) or help prevent development of the disease. How much is enough? To condition your heart and muscles safely, consider three aspects of exercise: Frequency - Exercise at least 3 to 4 times a week. Duration - Set a goal of at least 20 to 30 minutes a session. If time is a factor, three 10-minute sessions can be as beneficial as one 30-minute workout. If you're not used to exercise, start at a comfortable length of time and gradually work up to your goal. Intensity - Aim for about 60 percent of your maximum aerobic capacity. For most people, 60 percent capacity means moderate exertion with deep breathing, but short of panting or becoming overheated. You'll reach this level of exertion in activities such as brisk walking, golfing on foot, slow biking, downhill skiing, calisthenics, light gardening, raking leaves, cleaning window, hanging wallpaper, interior painting, hunting and slow dancing. Yet any regular activity, such as walking across the parking lot or taking the stairs, is more healthful than none. Remember the terrible "toos" The risks of exercise stem from doing too much too vigorously, with too little previous activity. If you've been inactive, the American College of Sports Medicine recommends a stress test if you're a man older than 40 or a woman older than 50, or if you have two or more risk factors for heart disease such as smoking, high blood pressure, high blood cholesterol, excess weight, family history or an underlying health condition. But remember, most heart attacks occur during rest. Instead of worrying about risks, use this latest information as an incentive for getting in shape with regular activity Exercise that's equivalent to burning about 1000 calories a week significantly lowers your overall risk of a heart attack. By walking briskly for 30 minutes several times a week, y ou can burn 1000 calories easily without resorting to excessive, vigorous activity. What it means to be "fit" Fitness means a well-conditioned cardiovascular and muscular system. Both your heart andmuscles need regular workouts to stay fit. You're fit if you can: Carry out daily tasks without fatigue and have ample energy to enjoy leisure time pursuits. § Walk a couple of blocks or climb one or two flights of stairs without becoming "winded" or feeling heaviness or fatigue in your legs. Carry on a conversation during light to moderate exercise such as brisk walking. If you sit most of the day, you're probably not fit. Signs of deconditioning include feeling tired most of the time, being unable to keep up with others your age, avoiding physical activity because you know you'll quickly tire, and becoming short of breath or fatigued after walking a short distance. Information in this letter is for general reference only. You should consult your health professional for individual medical problems. Mayo Clinic does not endorse any company or product |