Slightly irregular HR during exercise?

Hi, just need a little bit of advice here:

Quick history: A couple of years ago, I got heavy palpitations (quick heart rate and thumps in my chest and neck) and irregular heart rate while carrying a rather significant amount of cash (equal to $10.000) to the bank through a bad neighbourhood (it had to do with work - no criminal activity). For some reason, I related the palpitations to walking and not the neighbourhood, and I got palpitations when working out after this event. Holter monitoring confirmed PACs (not PVCs). Other tests were completely clean.

Anyway, I started using a beta blocker (10-20 mgs of Pranolol), some magnesium and Omega-3, and started exercising 3-5 times a week, and the symptoms went away completely.

For a couple of days, I tried to measure my heart rate while exercising, not because I'm afraid, but I want to find an optimal heart rate. I cannot help noticing my heart rate is slightly irregular sometimes. It's regular - but once in a while a beat, or a couple of beats, seems somewhat "lighter" (but still the same rhythm) or a slight irregularity like one beat is slightly delayed and somewhat stronger. It happens perhaps once every 30-40 beats.

I have absolutely no symptoms, and if I didn't measure my heart rate I would never have noticed it. When I had PACs, they were VERY noticeable, and it's not a skipped beat per say, just a slight "delay" before the next beat, or a "light" heart beat appearing right where it's supposed to. It possibly have some connection with my breathing, but I'm not really sure. At rest, I can have quite pronounced sinus arrhythmia, but I thought this was supposed to go away with higher heart rate.

Anyone else experiencing this? I'm not afraid or complaining, just a little curious.

[Brooke_38]

Just like other muscles; the heart responds to exercise with increased efficiency. Sometimes, the changes can be a bit unnerving and cause one to think that something is seriously worng.

Generally as we becomes more fit, our resting heart rate slows - a sign that our heart is pumping blood with greater efficiency. In the first six to 12 weeks of training, resting heart rate decreases by five to 10 percent.

The resting pulse of a trained heart is usually less than 70 beats per minute. Many athletes monitor their heart rates while exercising and while at rest (either immediately upon awakening or after 10 to 15 minutes of inactivity). But sometimes the results are unsettling.

For instance, you notice a skip between beats. Skipped heartbeats are usually premature heartbeats - one beat quickly follows another, and the resulting pause in the rhythm of your normal heartbeat is assumed to be a "skipped" beat. Occasional premature beats do occur in healthy people and usually don't indicate a problem unless they're accompanied by chest pain, light-headedness or other symptoms.

The description you give sounds likely to be termed "Phasic Sinus Arrhythmia", a pulse that speeds and slows with respiration. Up to 69 percent of aerobically trained athletes demonstrate phasic sinus arrhythmia. This benign rhythm discrepancy becomes more common as you become more fit; it temporarily disappears when you increase your heart rate with exercise. The rate can be anything from regular to irregular and the same with the rhythm; regular to irregular. If you don't have any serious symptoms, those that I mentioned above, I'd think nothing more about it and continue your "heart healthy living" :)

[is_something_wrong]

Thanks ;)

I know this is likely to be sinus arrhythmia. I'd just hate to get those PACs back again during exercise. A PAC or 20 now and then at rest doesn't bother me, but atrial trigeminy during exercise was a bit frustrating. I'm happy the betablockers help, but I just got afraid they now was masking the symptoms instead of removing the premature beats.

I know I'm whining about nothing here. I'll just keep exercising and ignore them.

My resting heart rate is 50 by the way, so maybe those hours on a bike start to help ;)

Thanks again :)

[kay2486]

beta-blockers slow your heart down and keep it under control so even when you exercise your heart wont go much faster than resting heart, beta-blockers have loads of side effects and one of those is irregular heart beat, i wouldnt be worried unless you get breathless longside it.  Ive had a break from reading cardiology, my doctor told me if i want to look up anything on the internet then a website to look at is www.patient.co.uk its what doctors use too so the text is different, im still coming to terms with pvcs and learning they arent dangerous.

If i were you id stop counting your pulse, get rid of whatever heart equipment you have or hide it, you have nothing to worry about as you've seen a lot of doctors, i find it easier to ignore pvcs if i dont check my pulse every so often i feel so much better, it is difficult to get out of the routine of doing it though.
I found a panic away programme and it works, it also tells us the heart doesnt beat regulary or in rhythm all the time it will have it moments when it beats irregular or harder with no underlying problem, its the heart and it knows what its doing so let it do its job and stop checking it.