Pumping Marvellous

This article talks through the effects of intensive and prolonged exercise without recuperation and shouldn’t be confused with regular exercise.

Too much exercise can scar the heart and increase the risk of sudden death, experts claim. Research shows that extreme endurance sports such as marathons, triathlons and long-distance bicycle races can cause structural changes to the heart and large arteries.

Usually recovery occurs within a week. But for some individuals, repetitive injury over months and years of training and competition can lead to patches of fibrosis, or scarring, in the heart, say scientists. This can lead to an increased likelihood of potentially fatal abnormal heart rhythms.

Dr James O’Keefe, from Saint Luke’s Hospital in Kansas City, US, who led a review of the evidence, said: “Physical exercise, though not a drug, possesses many traits of a powerful pharmacologic agent. A routine of daily physical activity can be highly effective for prevention and treatment of many diseases, including coronary heart disease, hypertension, heart failure, and obesity.

“However, as with any pharmacologic agent, a safe upper-dose limit potentially exists, beyond which the adverse effects of physical exercise, such as musculoskeletal trauma and cardiovascular stress, may outweigh its benefits.” The research is published in the June issue of Mayo Clinic Proceedings.

Endurance sports such as ultramarathon running or professional cycling have been associated with as much as a five-fold increased risk of atrial fibrillation, one kind of abnormal heart rhythm, say the scientists. Excessive sustained exercise may also be linked to coronary artery calcification, and dysfunctional and stiffened large arteries.

One study showed that around 12% of apparently healthy marathon runners had signs of heart scarring. Their chances of suffering a heart-disease event was also significantly higher than average. A famous victim of excess exercise may have been legendary US ultramarathon runner Micah True who died suddenly while on a routine 12-mile training run on March 27, it is claimed. True, nicknamed Caballo Blanco (Spanish for “white horse”), would run as much as 100 miles in one day. After death at 58, his heart was found to be enlarged and scarred. He died from a lethal heart rhythm irregularity.

What are are Implantable cardioverter defibrillators

People who have a particular sort of abnormal heart rhythm, called pulseless VT (ventricular tachycardia) or VF (ventricular fibrillation), may need to have a device fitted called an ICD. Ventricular tachycardia is when the heart beats too fast, and this means that there is not enough time for the heart to fill with blood properly between beats (contractions), so not enough blood is pumped round the body.

In ventricular fibrillation, the heart rhythm is so abnormal that the heart no longer contracts, but quivers instead. This results in death, unless an electrical shock is given to the heart to restart it.

An ICD works by constantly monitoring the heart rhythm. If ventricular tachycardia is detected, the ICD will try to correct it. If this does not work, the ICD will try to bring the heart back to normal by giving it a small, controlled electrical shock. If this fails, the ICD will deliver a larger shock, which is known as defibrillation.

If the ICD detects ventricular fibrillation, it will defibrillate the heart immediately.

As with pacemakers, ICDs are implanted in hospital, usually under local anaesthetic and complications are rare. Like pacemakers, you will need to avoid things that can interfere with the way in which the ICD works, such as airport security systems.