I was on a treadmill at the club and bumped up my intensity (at the time my pulse was 150'ish). Before I knew it, my heart just started racing and I got lightheaded... so I started slowing down the treadmill. Next thing I know, I'm waking up and asking, "Why did I fall asleep on the treadmill?" Long story short, went to the doctor and had EKG and bloodwork done, and she said I had Premature Ventricular Contractions (PVC's). She suspects that I may have fainted because of dehydration; and that dehydration is sometimes the cause for PVC's. Got a follow-up appointment today, and they'll probably give me another EKG and a holter to wear for 24 hrs to monitor the PVC's. I also picked up a basic Polar A5 heartrate monitor to ensure I don't get my heartrate too high again. Obviously my "perceived rate of exertion" isn't accurate.

Anyone else here have this type of problem? I've seen other threads about folks with PVC's, but never heard of anyone passing out.

After long rides . I seem to be vunerable for syncope . ie .. over training or dehydration and suger imbalance . Do you drink lotsa of milk ? Its really bad for you . causes diabetes among other things

Yep..Saturday after a really hard run - not on the bike -after @ home.
Went down twice.

Second time I smacked my head.

I have a tendency to faint too, but not for the reason you have. It's important for me to stay well hydrated and consume lots of salt. Really hot weather can be a problem. It's a problem of the autonomic nervous system.

Many things can cause syncope - it's good that you have a diagnosis, and I hope it doesn't keep you from exercising the way that you would like.

If you are thin..I think it happens to a greater degree, the rapid loss of sugars etc.
Dehydration is a factor and electolytic? action.
Also more blood is below your heart, any vascular constriction even if perscription could maybe affect how much gets to the brain.
The other thing I can think of is oxygene. a room with 'filtered' air is pretty full of c-dioxide, c-monoxide. Small factors can add up, evena pollen allergy. But still, the tests are good for re-asssurance.

Hey- if i'm stressed, I get a mild hypertension..biking cures it though..hypertension while biking would be a drag.
Why I don't yell at cars.

Best to you.

Had a follow-up today. My thyroid, electrolytes, potassium, etc were all normal. Blood pressure and oxygenation were all good. They ran another EKG on me today - no PVC's but my heartrate was only 49 when it's usually around 60-70. So he's referring me to cardiology to be on the safe side (mentioned something about possible pacemaker down the line) and I'm getting a holter next week to monitor my heart for 24 hrs. In the meantime, he told me only light exercising (not-too-brisk walking, yoga, stretching, etc.) until I get the okay from the cardiologist. Kind of a bummer, but I guess I can ratchet it back for a few weeks.

As for milk, no I don't drink it cuz I'm lactose intolerant. And I'm not thin, actually a little overweight (which is what I'm trying to remedy). So I guess I'll just have to keep an eye on consumption for the next few weeks....

Not being able to exercise in the interim is a big drag, but it could be worse. When I was getting the cause of my syncope diagnosed (there was a possibility it was seizures), I wasn't allowed to drive at all, making it really tough to get things done. One of the faints was at a conference I had driven 4 hours to - fortunately, some friends were there too and did me a tremendous favor by driving my car back for me.

However, it was OK for me to ride my bicycle. Thank goodness for that.

Syncope (fainting) with exertion can be a symptom of more serious heart conditions - rhythm disturbances with or without ischemia (coronary disease related lack of blood flow) or valve abnormality especially aortic stenosis. MANY times it isn't and is a simple faint related to things like overexertion. IMHO anyone who passes out exercising should not return to that level of exercise until they have a stress test (i.e. treadmill or cycle exercise test) at a minimum.

Good luck

Yeah, it's a bummer not to ride... but I will at least get to take strolls out (the weather's really nice right now) with my friend, and go to yoga. I figure that I won't even do any of these alone in case I pass out again. Will be wearing my heartrate monitor too just in case. Will keep you posted.

I become vunerable for syncope after rides of 70 miles or more . Im not sure if I want to see a doctor . since it only happens in extreme situations .

I lucked out - a cardiologist appt opened up today and he looked at all my EKG's and bloodwork and said everything actually looks fine. He thinks I was dehydrated and that caused my fainting. The PVC's were probably brought about from the stress of the day, dehydration and caffeine (I drink a lot of coffee). He said that, if I keep hydrated and cut back the caffeine, I can exercise as usual as long as there is someone else around in case I faint (which he doubts will happen). The holter is still going to monitor my heart next week and he's ordered an echocardiogram (to be extra safe) in a couple weeks; but he suspects that this is a singular occurence. While he says I can resume as before, I will be using my heartrate monitor to ensure I don't go over 85% and will eliminate all that coffee. I eased back in today with 30 min on the elliptical and 15 on weights. It's just a bummer that I can't bike alone cuz it's hard to find folks to ride during the weekdays with me. But oh well, at least it's not anything too serious... and when I get the results of the holter and echo back, I can probably ride alone again.

I had something similar happen to me about 7-8 years ago. I was working out like a maniac (lots of stair-climbing). Then, while driving home, my heart just went off the handle - beating uncontrollably fast. I had to pull over for a minute, but it only lasted a few seconds. I didn't faint, but I think I probably came close. Happened another time or two, but then, I used the val salva manuever to quell it. This is when you close your mouth, pinch your nose and blow gently. It's a technique used by scuba divers to equalize the pressure in their sinuses when descending (same idea as yawning, chewing gum, etc. when gaining/losing altitude). This does have some effect (on the vaso-vagal nerve? don't quote me - I'm not a doc), and would be a good thing to remember.

Long story short, I did have PVC's as well, but nothing to worry about according to docs. Of course, for months, I worried like crazy which made it worse. There is nothing like getting older and thinking about your own mortality to stress you out! Somehow I settled down (I do limit my caffeine now), and haven't had that problem again, knock on wood. You should definitely get checked out by the cardio guys, but here's a vote for also reducing stress in your life - it really does have an effect.