(My wife found the incompetent heart thing pretty funny.) And the nurse who did the ECHO, which is an ultrasound of the heart, said my left atrium is severely dilated, which could indicate years of hard riding, or a problem. The nurse who did the treadmill test speculated that the low heart rate could be fromВ chronotropic incompetence. The first doctor listened to my story, looked at some of my heart-rate and power data from previous rides, and said, вЂњItвЂ™s probably nothing, but letвЂ™s do an EKG just in case.вЂќ When the EKG returned results for a first-degree heart block (which sounds much worse than it is!), he said, вЂњWell, itвЂ™s probably nothing, but I want a cardiologist to tell you that.вЂќ So I went to a cardiologist, who effectively said, itвЂ™s probably nothing, but letвЂ™s do an ECHO and a treadmill test. In light of my friendsвЂ™ experiences, my weird heart-rate drops, combined with chest pain when just hanging out at the house, prompted me to go see a doctor. When I ease off on the pedals, my heart rate will jump back up to where it was.ДЄfter seeing weird fluctuations in my heart rate on hard rides, i went to get it checked out Seeing unexpected drops in heart rate (in red at right) while riding hard sent the author in for tests with a cardiologist In the past year IвЂ™ve been experiencing heart rate fluctuations in the other direction, where my heart rate will drop from 150 to 100 or below - while riding hard and steady at or just above threshold power. VeloNews managing editor Chris Case wrote an eye-opening story about some extreme cases of heart problems in cyclists, centering largely around our friend Lennard Zinn. In most cases they have tachycardia, where sometimes their heart rate will rev up to 180, 190 or even 200bpm when it should be somewhere around 150. WhatвЂ™s clear to me is that six guys I ride with or used to ride with have diagnosed heart issues, and I know of more through mutual friends. The million-dollar question, of course, is how much is excessive? There is no clear answer. John Mandrola and cardiologists like Dr Lisa Rosenbaum have argued that a number of studies show an association between excessive exercise and abnormal heart rhythms. Although this is a debated subject among the experts, cardiac electrophysiologists like Dr. вЂExtremeвЂ™ endurance athletes, such as those of us who ride a lot, may be at a greater risk for developing atrial fibrillation, which is an irregular, usually high, heart rate that interrupts the normal rhythm.

Dizzy after mtb ride