Recent exercise program causing palpitations?

I am a 36 year old male, about 195 lbs, and 5'11".   I sit in front of a computer most of the day and have had a very sedentary lifestyle the last few years.  Recently, I've decided to change that and for the past few weeks have been taking brisk walks of 1.5 - 3 miles most mornings and evenings and doing some strength exercises (dumbbells, crunches, etc) and have been trying to eat better and cut out caffeine and sugars.

In the past, I have experienced anxiety and panic attacks (though not for a few years) and have dealt with accompanying palpitations.  Now, about 3 weeks into my new exercise program, I am starting to get palpitations during the day, while sitting at my computer.  I also sometimes feel them when I'm starting a walk, however, it seems that once I warm up a bit, I don't feel them anymore.  It actually seems like the only time lately I'm not feeling occasional palpitations is when I'm in the middle of a walk.

It's very difficult to focus on my work with these frequent, anxiety-producing palpitations, and I'm concerned about whether I'm putting too much strain on my heart all at once.  Is it likely that the palpitations will go away if I continue my routine, or would easing back a little be prudent?  In any case, I assume seeing a doctor would be a good idea, but I'd like to get other opinions as well.  

Thanks much.

[debbier]

Good for you for making a change and getting healthy,   I would definetly check with a dr, maybe wearing a holter monitor for a few days while you excercise will give the dr the information you need.      It could be now that your moving and getting your heart rate up your more aware of your heart rate and feel the pvc's more.      Good Luck!

[is_something_wrong]

What you are experiencing is very common, and almost a classic anxiety symptom. I have this problem myself from time to time, getting heavy palpitations early during exercise. I can 100% relay to your problems.

Palpitations during exercise are usually caused by premature atrial contractions (PACs) in other words normal heartbeats that origin somewhere close to your natural "pacemaker".They are conducted through your heart through normal pathways, they do not reduce your cardiac output, and they are essentially completely benign.

When you start exercise, you will get elevated adrenaline levels, and with a somewhat high "baseline" adrenaline level due to anxiety (and especially if you have this on your mind and expect them) will make your heart do some extra beats. It usually settles later during exercise when adrenaline levels are more normal, you are reassured, feeling "this wasn't so bad after all, I survived, etc.)

It's fairly normal get aware of palpitations when resting, between panic attacks (panic attacks usually cause sinus tachycardia, normal high heart rate, or the skipped/double beats just disappears in the mess a panic attack can create). I'm famliar with this problem, too.

I agree with debbier's answer, it's a good idea to see your doctor and get the necessary tests done, just to rule out any problems and, more important, get this out of your mind.

What I maybe disagree, is this being PVCs. Palpitations during exercise are usually PACs.