Endurance Training May Lead to Pacemaker Later
Intense exercise messes up a heart-regulating protein, says study
By Kevin Spak, Newser User
Posted May 14, 2014 7:00 PM CDT

(Newser) – Could exercise be—gasp!—bad for you? Well, not exactly, but there is a downside to too much of it, a new study from the British Heart Foundation has found. In mice, endurance-based exercises were linked with a drop in production for a key heart-regulating protein, resulting in lowered heart rates of the subjects, the BBC reports. The finding may explain why human fitness devotees often have lower resting heart rates—sometimes with dangerous lapses between beats—making them more likely to require a pacemaker as they age.

In the past, people have believed that it's the nervous system's increased activity that tricks athlete's hearts into slowing down. "But our research shows this is not the case," says the lead author, according to the Times of India. "Actually the heart's pacemaker changes in response to training." But sorry, couch potatoes: The researchers said that overall, the benefits of working out exceed the drawbacks. (Click to read about a previous study suggesting that moderate runners live longer than those who log mega-miles.)

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May 15, 2014 6:34 PM CDT
This is a study on mice. I would like to know what is considered "endurance training" for a mouse, and how did they persuade the poor mice to work that hard. Perhaps it was the constant harassment/torture needed to keep the mice moving that caused the problem and not the exercising itself. I would also like to know what kind of diet the mice were receiving during this extreme testing.
May 15, 2014 10:05 AM CDT
Everything in moderation, including moderation. Words to live by.
May 15, 2014 10:03 AM CDT
1. Guess what, we're all dying anyway. That's not what it's about. It's about looking and feeling your best while you're here. 2. I want to know what they are considering "endurance " training. Are they looking at purely long distance cardio, HIIT training, etc? Why do I ask - because most marathon runners I know would be the first to tell you that running marathons isn't particularly good for you. Doing anything past a logical point of moderation isn't good for you. I doubt these findings are true for those of us who HIIT train or do combo weight lifting and cardio sessions for 45 minutes to 2 hours, 4 times per week, and are otherwise just mindful to do things like ride our bikes or walk instead of driving. 3. Exercise is good for you. People who exercise are generally happier, more successful and sick less often. 4. Studies like this are retarded. They generally study the extreme and then advertise the results like they are studying a normal person's exercise routine, and freak people out for no reason.