Fitness in the Long Run

How to have a safe marathon: heart-wise?

Dr. Akshay Mehta - MD, DM.
Interventional Cardiologist
Nanavati Superspeciality Hosp., Hinduja Healthcare, Breach Candy Hosp.


It is common knowledge that physical exercise promotes health and prevents heart disease and heart attacks. However, we also sometimes see young, healthy looking people having heart attacks or dying suddenly during training or during marathon running.

Why is this paradox? And what can we do about it?

Well, the difference is between moderate regular exercise which has all the benefits of exercise minus its risks, versus intense, vigorous exercise, which has slight additional benefit but with increased risk, especially if unaccustomed.

The risk of vigorous exercise like running or training for a marathon comes from interplay of two factors:

  • Underlying heart disease (most commonly fatty plaques in coronary arteries) which may or may not be detected by routine tests such as blood tests, ECG, or a stress test.

  • Surge of chemicals like adrenaline and increased shear stress on coronary arteries which may cause rupture of these fatty deposits (plaques) as well as disturbance in heart rhythm. Also, with vigorous exercise, especially if unaccustomed there is ACTIVATION OF A TYPE OF BLOOD CELLS CALLED PLATELETS. When activated, these can clump together and initiate clot formation at the site of the ruptured plaque in the coronary artery. This clot along with the fatty deposit and with possible spasm of the artery can suddenly block the blood flow in the coronary artery which leads to heart attack or sudden death.

  • (A third factor recently found in marathon runners has nothing to do with heart disease, but with excessive heat and dehydration causing heat stroke).

Hence, to prevent a cardiac catastrophe on vigorous exercise we need to do the following:

  1. If you are above 30 years of age or younger than that but with risk factors such as smoking, hypertension, diabetes, lipid (cholesterol) abnormalities, or have a family member who has had heart disease, or have unhealthy lifestyle (frequent and regular intake of sugar, trans- fats or processed very high fat food and total lack of physical activity) and mental stress, you should undergo PROPER CHECK UP BEFORE JOINING the exercise program. This consists of clinical examination by a cardiologist, ECG, blood tests and a treadmill stress test. Even while you are regular on an exercise program, it is advisable to undergo these checkups once a year if you are above 30 years of age or have one or more of the risk factors listed above.

  2. In many people, these routine tests do not reveal an underlying abnormality, despite having fatty plaques and being susceptible to heart attacks during vigorous exercise. Hence additional tests such as a coronary artery calcium score (CACS) may be advisable. CACS is a 'score' which tells the amount of calcium in one's coronary arteries and a direct evidence of amount of calcified fatty plaques . Higher the number of these plaques (CAC score) higher the severity of coronary disease and chances of a cardiac event in future, whereas a score of zero implies absence of calcium containing plaques (doesn't rule out soft plaques) . CACS does not require injection of any liquid but has the disadvantages of cost as well as slight but definite exposure to radiation (equivalent to about 10 chest X rays) which could be 'potentially' carcinogenic.

    - A still better test to reveal all kinds of fatty plaques in the coronary arteries is a CT coronary angiogram which has still higher risk of radiation (equivalent to about 30 to 60 chest xrays) and potential effect on the kidneys due to the liquid contrast injected. It should be clearly understood that both these above mentioned tests are as yet not recommended as mandatory or routine in people without symptoms before joining a vigorous exercise program.

    - However, looking at the higher incidence of heart attacks in young Indians (3 to 4 times that in westerners), and inability of routine tests like an ECG or a stress test to pick up disease in many, these tests may be worth a consideration- but only after talking to one's cardiologist, and after fully understanding the risks versus benefits of such tests.

  3. A 2 D Echo is advisable in people who have had heart attacks, angioplasty or bypass surgery in the past or have some abnormality detected during clinical examination by the doctor or an abnormal ECG. 2 D Echo is a safe procedure for everyone but adds to the cost. It can reveal structural or functional abnormalities of the heart which may not be picked up on routine clinical exam. It does not reveal the state of coronary arteries.

  4. Proper control of risk factors like hypertension, diabetes and abnormal cholesterol with healthy lifestyle and addition of medications if required.

  5. Use of preventive medications such as statins and low dose aspirin, on the basis of your risk defined by clinical evaluation, routine tests and your coronary artery calcium score (if done) and after medical consultation. Statins have been proven to shrink and stabilize fatty plaques and prevent them from rupture. Aspirin prevents clumping of platelets. Extension of same benefits during vigorous exercise may prevent a heart attack.

  6. Starting slow - when starting afresh. For initial week or so exercise at very low intensity and pick up in intensity and duration after a few weeks of lighter exercise. Same precautions should be observed when RESTARTING after a break of more than a week. Warming up and cooling down at every session, each for about 5 to 10 minutes.

  7. BEING REGULAR. Out of all the characteristics of an exercise program, this is the most important. Regular means at least five times a week, round the year. IF THERE IS A GAP OF MORE THAN EVEN A FEW WEEKS, START ALL OVER AGAIN WITH LOW INTENSITY EXERCISE AS ABOVE.

  8. Avoiding prolonged sitting in front of TV, computer or work desk or if possible, have frequent "standing" breaks.

  9. Listening to your body : STOP exercising and go to your doctor or hospital if you have any of the following feelings at any time before, during or after exercise: tightness or heaviness in chest, unusual breathlessness, fainting or dizziness, nausea or vomiting sensation, pain the back, arm, jaw or throat or unusual gas or indigestion. It could be a warning sign of an impending heart attack.

  10. Ensuring proper rest or sleep for 7 to 8 hours daily. If your sleep has been less the previous day or night, or if you have not rested well the previous day, skip the next exercise session or make it very light.

  11. Finally one must remember, regular moderate exercise is no guarantee against heart disease if you also indulge in unhealthy eating habits or smoking or heavy alcohol consumption. So these have to go if you want be "heart-safe".

In summary if you have been 'screened' properly (including a CACS, if deemed appropriate), if you make a gradual entry into an exercise program, building up your stamina and endurance slowly and safely, noting any unusual symptoms at any time, are leading a healthy lifestyle with diet, regular exercise and sufficient sleep, using protective medications if advised and enough fluids, you are sure to minimize your chances of a heart attack and are on the road to success without tears.