We are generally less active now than in the past. This is because newer technologies are making our lives easier and we are getting lazier. We move around less and burn off less energy than people in the past. Research suggests that many among us spend more than seven hours a day sitting and in over 65s, spend more than 10 hours sitting. We have all been told repeatedly that to stay healthy we must exercise regularly. Lack of exercise is associated with numerous health conditions, including obesity, heart disease, stroke, cancer, diabetes and osteoporosis. Most of us know how beneficial exercise is for our health. However, it is surprising how little many of us know about the dangers of being unfit. The number of overweight people is growing alarmingly fast all over the world. Department of Health in UK describes inactivity as a “silent killer”. So act now if you are not already at it. How does exercise help? To improve health through exercise it is necessary to make your heart beat faster. When it beats faster it forces more blood thereby oxygen to every organ in the body. This is one of the reasons why the whole body benefits by exercise. There is however a maximum safe rate at which a normal heart can beat. This will depend on your age. We will come to this later. Muscles and Heart: When you exercise regularly, you strengthen the muscles that do the work. To supply the muscles with enough oxygen during the work out, the heart has to work faster. This increased work load (within safe limits) will strengthen the heart muscles. Keeping the heart healthy is the key to the overall benefit you gain through exercise. Unfortunately, when you stop exercising all the benefit gained is slowly lost. Kidney: The increased blood flow through the kidney helps to get rid of unwanted chemicals (urea, ammonia, uric acid , etc) that are by-products of digested foods. Brain: Irrespective of age increased blood flow through the brain improves memory and learning function. It will also delay the onset of Alzheimer's in people who are prone to it. Bone: Regular exercise helps maintain stronger muscles and bones particularly in the elderly. Total inactivity results in weak muscles and loss of minerals from the bone resulting in osteoporosis. Immune System: With regular exercise you generally become more resistant to infections. Endocrine System: Exercise has a beneficial effect on the glands that produce different hormones. One of them relates to diabetes where it becomes easier to control blood sugar level. People with type 2 diabetes have too much glucose in their blood, either because their body doesn’t produce enough insulin to process it, or because their body is resistant to insulin. Exercise helps the muscles to use glucose without insulin. What this means is that through exercise the blood glucose level will go down whether you are insulin resistant or there is not enough insulin being produced. Type of Exercise: As mentioned earlier, the aim of any exercise is to increase the heart rate to its optimum level. You can do this by a variety of activity like jogging, cycling, swimming or brisk walking. Depending on your age and your physical fitness, you decide on the type of exercise to do. If you have never exercised before it is best to start with simple walking, extending it slowly to 20 minutes a day. To stay healthy, adults should aim to achieve at least 3 hours of moderate to vigorous physical activity every week. You'll get the most from your workouts if you're exercising at the proper exercise intensity for your health and fitness goals. Research has shown that interval training, ie higher intensity exercise done for short bouts (1 minute) interspersed throughout your workout, is well tolerated, even by those with certain cardiac conditions. This type of workout is very effective at increasing your cardiovascular fitness. Irrespective of the type of exercise you indulge in, never overdo them. If at the end of the session you are very tired or exhausted, you have exceeded the optimum level and that will cause more harm than good. Simple Tests to check health of your heart before you start exercising: Most heart problems start after the age of 55. If you are past 55, there are some simple tests that you can do, to determine if your heart is healthy. 1 . Check your pulse when you are sitting calmly and resting. It should be anything between 60 to 75 per minute. Next climb a flight of stairs or walk for two minutes and check your pulse. It should have increased by at least 10%. If it has not increased, you should see a doctor. 2 . Check your pulse before you start any activity (brisk walking, going up the stairs, running etc). Next check the pulse at the height of your activity. Stop all activities, sit down and rest quietly. Note the time. Check your pulse 5 minutes later. The pulse should have returned to the pre-activity level (resting pulse). The fitter you are the quicker it returns to pre-activity level. If the pulse remains high, you need a medical check. 3 . Heart Recovery Rate: HRR gives you a more accurate picture of how healthy your heart is. This is measured after you have undertaken a vigorous activity like running or brisk walking to increase your heart rate to the maximum permitted level. Check the pulse rate when your activity level is highest. Stop your activity abruptly, sit down and rest quietly. Measure your pulse rate exactly two minutes after stopping your activity. The difference between the two gives you the HRR. The higher the rate the healthier your heart is. If it is less than 22 you have a heart problem that requires urgent investigation and treatment. As I said earlier, to benefit from any exercise you must make your heart beat faster. Depending on your age there is a safe maximum rate at which your heart can beat. There is a simple formula to check the maximum heart rate that your cardiovascular system can cope without causing a heart attack. Formula for calculating the safe heart rate (HRR): • HRR = 220 – your age x 80/100. • Example: if you are 60, then 220 – 60 is 160. This the maximum rate you can subject your heart to. However, a desirable safe level should be 80% of 160 which is 128. Caution: Do not attempt to check how healthy your heart is if you are already on medication for a cardiac problem. Check with your doctor to determine if you are fit enough to undertake an exercise that will increase your heart rate. Seeking Medical Help: Several types of medications can lower your heart rate, therefore, you may need to lower the maximum rate your heart can be subjected to. Ask your doctor if you need to lower your target heart rate because of your medication or other medical conditions you suffer from. When you start your exercise, if you develop any of the following symptoms you must stop immediately and get yourself checked by a doctor before you proceed further. 1 . Shortness of breath. 2 . Pain in your chest 3 . Radiating pain to your shoulder, arm, neck or jaw. 4 . A tight feeling in your chest 5 . Feeling dizzy 6 . Feel sick 7 . Profuse sweating soon after you start any exercise When any of the above symptoms occur during normal everyday activity you must see your doctor urgently to check your heart and lung function. Conclusion: All health professionals now agree that to stay healthy you must exercise regularly. Dr. I-Min Lee, Professor of Medicine at Harvard Medical School said that middle-aged person who gets the recommended 150 minutes per week of moderate exercise like brisk walking, can expect seven extra minutes of life gained for each minute spent exercising. National Institutes of Health, USA concluded that a little physical activity can go a long way toward extending your life, regardless of your weight. People who walked briskly or did other activity at only half the recommended amount gained nearly 2 years in life expectancy compared to inactive people and those who exercised even more gained up to 4.5 years of life. K. Badrinath I am grateful for Dr. S. Vaithianathan Prof. of Cardiology in Chennai, India for reviewing this article before publication