Sunday, December 02, 2012

Too many marathons can kill, warn doctors

Doing too many marathons could kill you, doctors have said in a stark warning about the dangers of taking too much vigorous exercise.

Fitness fanatics should do “just one or a few” marathons or full-distance triathlons, say the cardiologists, because over-exerting the heart for years can lead to long-term damage.

There is now convincing evidence that repeatedly asking the heart to pump “massive” volumes of blood, for hours at a time, can lead to an array of problems, they say.

These include overstretching of the organ’s chambers, thickening of its walls and changes to electrical signalling. These could trigger potentially dangerous heart rhythm problems.

“In addition, long-term excessive exercise may accelerate aging in the heart, as evidenced by increased coronary artery calcification, diastolic ventricular dysfunction, and large-artery wall stiffening,” they write in the journal Heart.

Dr James O’Keefe and Carl Lavie, from St Luke’s Mid America Heart Institute in Kansas City, and the Pennington Biomedical Research Centre in Baton Rouge, US, say the heart is only designed for “short bursts” of intense activity.

They cite the example of Micah True, the hero of the book Born to Run about ultra-endurance running.

He died in March, aged 58, on a 12-mile training run in New Mexico. He routinely ran a marathon a day, sometimes more.

They believe that decades of such exertion led him to develop Phidippides cardiomyopathy.

Named after the original runner, who died delivering news of the Greeks’ victory at Marathon, it is “the constellation of cardiac pathology that has been in observed in the hearts of some veteran extreme endurance athletes”.

They concluded that most people should limit vigorous exercise to 30 to 50 minutes a day.

“If one really wants to do a marathon or full-distance triathlon etc, it may be best to do just one or a few and then proceed to safer and healthier exercise patterns,” they advise.

No amount light to moderate exercise is harmful, they note.

“A routine of moderate physical activity will add life to your years, as well as years to your life.

“In contrast, running too fast, too far, and for too many years may speed one’s progress towards the finish line of life.”

Ellen Mason, senior cardiac nurse at the British Heart Foundation, said: “Whether you’re taking part in an endurance event, watching your weight or staying healthy after a heart attack, it’s important to build up your activity levels gradually, especially if you’ve not exercised in a while.”


Citrus warning alarmist: medicos

WARNINGS about "killer grapefruit" have been blown out of proportion, according to two Canberra medicos who say it is safe to eat the tart citrus fruit unless specifically prohibited by your doctor or pharmacist.

This week the Canadian Medical Association Journal reported the number of drugs that can cause serious problems when taken with grapefruit increased from 17 to 43.

As little as one grapefruit or one glass of grapefruit juice can affect some medications and cause conditions such as irregular heartbeat, kidney failure, muscle breakdown, difficulty with breathing and blood clots.

And some very common drugs are on the danger list including cholesterol-lowering medication Lipitor, Verapamil, which is used to treat high blood pressure, and the chemotherapy drug Vincristine.

But Professor of Pharmacy at the University of Canberra Gabrielle Cooper said Australian pharmacists and doctors were aware of problem.

"Grapefruit has a strange interaction with a range of drugs and when a pharmacist dispenses that group of drugs they put a sticker on the box saying do not use with grapefruit," she said.

Dr Cooper said grapefruit can be a danger because it interferes with how drugs break down and can cause a drug overdose.

"There is an acidic interaction but there is also a metabolic pathway inhibition which occurs with grapefruit.It stops things being excreted normally.

"We have pathways in our body which have enzymes involved and that enzyme is inhibited by that grapefruit so it stops that drug being removed by the body in the appropriate time frame so you build it up."

Chairman of the ACT Medicare Local Board Rashmi Sharma said Warfarin, an anticoagulant that stops blood clotting, interacts with anything green.

"The take home message is that it's not just grapefruit juice that can affect the enzyme system, so without wanting to be alarmist it's important that people do tell their doctors what they are taking," Dr Sharma said.

And other citrus fruits including Seville oranges, limes and pomelos can cause the same effect as grapefruit.

"It's not a new warning, we were aware and as prescribers we warn our patients.'


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