I'm in my late 30s, riding 100 miles a week with no known health problems. About once a year for the past 25 years I get the palpitations described in the link below. Normally, I'm off the bike when these happen, so they go away after a few minutes.

https://www.ecureme.com/emyhealth/data/Racing_Heart.asp

But this time I was on the bike, riding to work at only medium intensity, when they started up. I pulled over for a few minutes and they seemed to slow down enough. But then when I started pedaling again I noticed that the heartbeat would get mildly uncomfortable once I started picking up speed. I was able to finish my ride, but only at low intensity to keep the heart rate down.

Time to see a doctor?

It wouldn't hurt to get the pump checked.

I was running, swimming and riding while training for triathlons about 15 years ago. I was in darn good shape. When I stopped, I would get those heart-skips-a-beat deals. It was just annoying, I never got dizzy or felt pain.

Went in for an EKG...everything was fine.

and your asking a bunch of non medically trained individuals why?

go see a doctor.

Yeah, honestly, go see a doctor. There are completely harmless conditions that can cause wierd heart behavior, and there are completely fatal conditions that can occur in healthy individuals. None of us is going to be able to diagnose which it is.

I used to get palpitations frequently due to anxiety attacks (which also mimic heart attack pains, shortness of breath, dizziness, etc...). I'm also diabetic, so my doc sent me off for a whole round of tests - stress test, ekg, blood work, the whole proverbial nine yards. Ticker was fine. Head's a bit of a problem, but the heart is good So, moral of the story? Go see the doc. If nothing else, it's good to get peace of mind and baseline records of your cardiac health for later in life.

I'm yet another person who's experienced this and can strongly recommend that you go to the doctor. In my case I had EKG and blood work done. Your doctor will also have your complete medical and family history to consider.

If you're asking here for support in wanting to see a doctor, you've got it--get it checked out!

Given that I also have a family history of heart disease, I went to the local doc during lunch, who was able to do the EKG and the blood samples. He gave me a reference for a cardiologist to do the rest of the tests, treadmill, etc.

I had that and the doctor found it to be sinal arrythmia (heart speeds up and slows down with my breathing makes it hard to check resting heart rate accurately when I wake up). Anyway, I get palpatations when I go from breathing hard and fast to breathing less (but not so much anymore, I think getting in better shape helped that). Go see your doctor and let him figure it out.

Get it checked out man. I hate going to the doc's myself, but I don't hesitate in suggesting other people go.

Go see a doc.
But here's something interesting. My wife had mercury poisioning from a bunch of amalgam dentil fillings.
Eventually she had them all replaced and had to go through chelation therapy. But during the ordeal, she suffered from anxiety/panic attacks which sometimes produced heart palpatations.
She is now A-OK.

Beware amalgam fillings, especially if you have a lot and also have a tendicy for anxiety.
https://www.generationrescue.org/mercury_dental.html

I can't agree more with the other responses. Get thee to thy physician.

My experience...I had a similar problem. Palpatations (felt like my chest was gurgling) about once a year for about forty years. I always attributed it to too many cigars until further reflection made me realize that they had been occuring when I was a non-smoking child. Suddenly they started occurring a few times a day and I became concerned. Went to the doctor who had me do a stress test. Nothing happened during the test but soon afterward as I was leaving the gurgling started. I ran back in and they documented the palpatations. Cardiologist did an EKG and told me I had a hole in my heart that had probably been there since birth. I was about 45 yo at the time of the diagnosis. Simple cathardization and one night hospital stay and I was fine. I walked around the hospital ward talking with the nurses the night of the "procedure" and drove myself home the next morning.

I would also get this, seemed like my hart was being kneaded like dough, or fluttering. I had it happen the first time in 84 when I was in the Navy. The ships Dr. said not to worry about it too much, so I didn’t. Last December I had it happen again, and again I didn’t think too much about it. I started my diet, and had a physical, and told my Dr. about it, and he had me do an EKG. Then he set me up for a stress test. I took that, and the heart Dr. said my heart would have an extra beat every once in a while, but nothing else showed up. I also had a ECG, and that also didn’t show anything. They think it may have been caffeine, which I did note I was drinking a lot of coffee, and diet pop.

Anyhow you are nuts not to get it checked out. Even the stress test was not bad, (I actually thought it was kind of cool) and now I know what it is, and how to deal with it. It was the best thing I ever did, because even though the ships Dr. told me it was nothing, I always scared me when it happened.

GET IT CHECKED ! !

Please see this thread for my insight on this issue.

Then get thee to a doctor.

I am having a PVI Ablation by a world famous physician in San Francisco (I live in Colorado) August 26th to correct Atrial Fibrillation, which first started as what I thought to be palpitations.

After the first time it happened on the bike two weeks ago (my first post above), I went into the local urgent care center. They did the chest xrays, EKG, and blood tests and everything was OK. They suggested I follow up with the cardiologist just to be sure.

Same symptoms happened on the bike another day last week. I finally made it to the cardiologist a couple of days ago. He heard a heart murmur, so he put me on the stress test. Turns out I have a valve that acts funny once my heart rate goes up, and it causes a skipped/extra beats and takes a while to get back to normal. But at least no heart damage or anything like that. He said it's treatable with medication (atenolol), the correct dose will have to be worked out through trial-and-error.

I forgot the name of the condition, but I've got a phone call into the doctor so he can tell me, so I can do an internet search for more information.

Good to hear it won't call for surgery. I get the impression, too, that it's not deadly when it does happen?

That's one of the things I want to research more. I'm sure it's not deadly when it happens, but it's rather unnerving.

I've asked for heart rate monitor (HRM) recommendations in this thread: https://www.bikeforums.net/training-nutrition/130372-hrm-recommendations.html#post1471978

I have a 10-year-old bottom of the line Polar HRM that measures heartbeat every couple of seconds or so. I'm thinking of upgrading to a model that would take more frequent measurements, so that I can catch the irregular heartbeats. But on the other hand I'm wondering if that's just setting myself up for anxiety, as I do tend to be a bit of a hypochondriac. Maybe I'm better off just keeping the old HRM and using it just to set a target maximum rate.

Speaking of heart rate, how do you determine the maximum heart rate when it is limited by a heart condition? If I were to calculate my theoretical max HR by the 220-age formula, I'd end up with 183. (I know that formula's not perfect, especially since the last time I used a HRM about 5 years ago, I knew that I could get my HR up higher than the 220 minus age formula.) But during the stress test, the heartbeats got so irregular when I reached a rate of 170-175, and the doc stopped the test. So do I use 170-175 or 183 as a basis for when I try to use % of max HR?