By Assoc Prof Tan Swee Yaw, Senior Consultant, Department of Cardiology, Director of Cardiovascular Rehabilitation & Preventative Cardiology, NHCS
While exercising, your blood pressure increases, and after completing a physical activity, your blood pressure is usually lower. Regular exercise helps regulate blood pressure and keeps blood pressure under control.When you exercise, your body expends energy and uses glucose and energy reserves. This reduces blood sugar concentration and helps your body regulate sugar metabolism.
Exercise increases the level of the good high-density lipoproteins (HDL) cholesterol and reduces low-density lipoprotein (LDL) cholesterol and Triglyceride (TG) levels. HDL cholesterol prevents deposits of cholesterol in the arteries, whereas higher levels of LDL cholesterol and TG will lead to increased deposits of cholesterol in atheromatous plaques in the blood vessels. Regular exercise reduces the chance of arteries becoming clogged with atherosclerosis (a condition in which plaque builds up inside the arteries).
When you exercise, you burn calories and increase your basal metabolic rate. Engaging in moderate physical exercise daily for 30 minutes, five to seven times per week helps in weight maintenance.
Studies have also shown that heart failure patients who are compliant with their medications and exercise regularly can improve their heart’s function and can build up better stamina and endurance.
Regular exercise reduces the risk of heart attacks and improves your longevity. Many studies have shown that an individual is less likely to get a heart attack, if one exercises regularly.
Many health guidelines recommend 30 minutes of moderate intensity exercise at five to seven times per week to keep our heart healthy. Singapore’s National Physical Activity guidelines recommend a similar 150 minutes of moderate intensity exercise every week. Activities such as taking the stairs, engaging in brisk walking and other aerobic exercises can contribute to this weekly target.
Exercise is even more important for patients with heart disease. After a bypass surgery or heart attack, it is recommended that eligible patients should attend a structured cardiac rehabilitation programme. This programme aims to educate patients on their cardiac condition, monitor the patients’ health status following their discharge from the hospital, help patients effect lasting appropriate lifestyle changes, and motivate them to participate in regular aerobic exercise.
The programme usually lasts for one to three months and can start a week after a patient discharges from the hospital. The patient should refer to his or her doctor’s recommendation before embarking on such a programme. NHCS offers a secondphase outpatient Cardiovascular Rehabilitation and Preventive Cardiology programme, for all patients with coronary artery bypass surgery (CABG) done or had been admitted to NHCS for heart attack. Many studies have shown that cardiac patients who attended the structured cardiac rehabilitation programme and participated in regular exercise had up to 25% reduction in the risk of future cardiac events.
One way to calculate one's maximum predicted heart rate for vigorous exercise is to subtract his or her age from 220 and multiply it by 0.85. Therefore, during a vigorous exercise, an individual can aim to keep his or her heart rate below this maximum heart rate.
While this formula may generally be acceptable for fit and healthy individuals, recent studies have found that a different method of determining a safe maximal heart rate may be a better option, especially for patients with pre-existing cardiac conditions.
During exercise, the body goes from an initial aerobic state to a ‘stressed’ anaerobic state, as the intensity of exercise increases. At some point during the vigorous exercise, the body will enter the anaerobic state and start to accumulate lactic acid in the muscles, causing muscle cramps. The point when this happens is called the ‘anaerobic threshold’.
It is postulated that if heart rate is kept below the anaerobic threshold, the risk of adverse cardiac outcomes during exercise is reduced. The heart rate at whence this occurs is best determined by a specialised cardiopulmonary exercise test machine.
A 2017 study by NHCS published in an international journal found that in patients with prior coronary artery disease, keeping the heart rate at this Anaerobic Threshold versus the traditional (220-age x 0.85) target, has resulted in far fewer abnormal electrocardiography changes.
Overall, regular moderate exercise is a fun and excellent way to stay healthy and to reduce the chances of developing heart disease. More importantly, patients should always check with their regular doctor to determine if it is safe to start an exercise programme.
In the era of the COVID-19 (Coronavirus Disease 2019) pandemic, the widespread implementation of movement restrictions, closing of gyms, parks and other exercise facilities pose a challenge for individuals to stick to their regular exercise regime.
Here are a few Do’s and Don’ts for this period:
✅ Continue regular exercise. Check with your doctor on the appropriate exercises you can do. Exercise at home with an exercise bike or treadmill, if available. Isometric exercises like planking are excellent in training your core muscles and can easily be performed at home.
✅ Use a mask when not performing strenuous exercise. Should you choose to go out and jog or have a brisk walk, bring along a mask with you. Remember to put the mask on when the strenuous portion of your exercise is complete.
✅ Keep a distance from others during exercise. Exercise should not be a social event. Recent research from Belgium revealed that runners and cyclists could potentially spread infective particles to other individuals 10 to 20 metres away if the affected individuals are in the exercising person's 'slipstream’.
✅ Practise good personal hygiene. Eventually, when gyms and communal exercise facilities open, it is imperative that all equipment, especially those with high touch areas are to be disinfected after each use. Virus can potentially stay viable on surfaces for a few days. Bring your own hydration supplies, avoid communal water coolers and water fountains.
❎ Do not exercise if you are feeling unwell and/or having flu-like symptoms such as fever, cough, runny nose or sore throat.This article is from Murmurs Issue 36 (January – April 2020). Click here to read the full issue.
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