Premature Atrial Contractions

Dr. Michael Kemelmen, a cardiologist, gave me a stress test today.

He cleared up what it is that I remember, from my last stress test some years ago, as being "odd" about my heart rhythm: I have "premature atrial contractions," or PACs. They're not to be confused with "premature ventricular contractions," PVCs. Neither PACs nor PVCs are particularly worrisome, but there's a small chance that PACs may be associated with valve problems, so I have to go back next week for an echocardiogram.

Dr. K says my "extra heartbeats" may be confusing my simple heart rate monitor, causing it to read high. That sounds like as good an explanation as any for why my measured heart rates seem too high for the amount of effort I'm expending when I jog. When I was hooked up to close to a dozen electrodes for purposes of the stress test, the final phase had me subjectively working much harder than I seem to be doing when I run, say, a 14-minute mile. Yet my measured heart rate was the same: about 165 beats per minute.

I imagine Dr. K's ultra-sophisticated BPM counter factors out my "extra heartbeats" from PACs. So when my cheap monitor says 165, the real number is lower, and I'm actually in the proper aerobic zone which books on exercise recommend.

Assuming my echocardiogram comes out normal, all this doesn't explain why I can't yet beat a roughly 13-minute mile, after two months of working out.

Nor does it explain why I have needed these last four days to recover from my prior near-daily workouts over the period of two months. After going to Basic Fitness class last Thursday — this is Monday — Friday I was near-comatose, and each day since then has seen me gradually get closer to a normal level of energy.

So I'm thinking that I simply can't sustain workouts more often than every other day. My recovery time is apparently too slow.

Failing to honor that constraint may be what keeps my jogging times too high. I've noticed that the improvements I actually have made in my jogging pace, recently getting down to a mile in just over 13 minutes, have tended to come after a day off.

So I'm thinking of cutting back to Tuesday and Thursday mornings at the Basic Fitness venue, plus one weekend morning jogging. That makes sure I don't work out on back-to-back days ... unless I decide to walk on the other weekend day. Then we'll see.