Last week there was a letter in cycling weekly by a chap called Barry Jones. He had developed atrial fibrillation during a ride. It had been blamed by him and by the medics on coffee. I think it’s an example of “attribution bias”. This is when you look for the reason you want, rather than the real reason, to explain away a problem

For many years, doctors were taught that caffeine led to heart rhythm problems. Doctors have been counselling patients to avoid caffeine when they present with palpitations. There is no doubt that in overdose, caffeine can indeed cause heart problems.

But, “normal” caffeine consumption and the risk of heart rhythm problems has now been looked at in several large populations. The bottom line is that, for most people who drink only moderate amounts of coffee, caffeine intake is not related to heart rhythm problems, including atrial fibrillation (AF). Caffeine can also improve performance. As a cardiologist with an interest in heart rhythm problems and exercise, I have had to change what I advise over time.

Sadly, there is growing evidence that AF is related to exercise. The risks of developing the condition are many times higher in athletes, and there is an apparent relationship between exercise volume and intensity, particularly in men. I see many cyclists and triathletes who develop this problem in middle age. It is incredibly frustrating for them. The story of an athlete’s heart rate monitor showing high heart rates for long periods of time (not just the brief spikes we all see) along with a drop off in performance is classic.

It is possible, as with everything in life, to have too much of a good thing. Overall, exercise appears to be beneficial to health, at least in moderation; the upper limits aren’t well defined yet. I keep exercising (moderately) with adequate recovery. Life is all about balancing risks. But don’t blame the coffee when your heart rhythm goes haywire. It’s probably a consequence of your epic suffer score. And do seek medical attention – there is lots we can do, and lots you need to know.

Some references, for those who are interested:



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