Beta blockers and “warming up”

In recent months, Jay and I have both had some troubling blood-pressure readings and have been put on hypertension drugs by our doctors. As luck would have it, we are both now taking metaprolol, one of the family of “beta blocker” medicines. Beta blockers have the general effect of slowing down the sympathetic nervous system, aka the “fight or flight” or adrenaline response. This means that when events would previously have caused your blood pressure to rise, it rises much more slowly; this of course has the effect of lower average b.p., which is the point. Another effect, though not the one being sought, is that your heart rate stays lower on average.

And therein lies the problem. Exercise requires a “warm up” interval, during which the heart rate is being brought up to a functional speed for aerobic exercise. Now, I don’t know much about the physiological reason for this, but I have found in the last few years that if I want to get a really hard workout, it is extremely hard for me to keep going for about the first half-hour, and then it suddenly gets easier.

It’s like, when I make a demand on my heart, it goes, “NO! NO! NO! SLOW DOWN! I CAN’T TAKE IT! I’M GONNA EXPLOOOOOOODE!!!!” at first. But then if I keep pushing through it, my heart finally says, “Oh, well then, if that’s what you want.” And stops protesting.

Now, the problem? The beta blocker slows everything down. This means that I am working hard for even longer to get through the “NO! NO! NO!” period. It also seems that I must work much harder during every minute to get my heart-rate up into the “Fat Burning” or “Aerobic” zones … you know, the ones you calculate as a percentage of your max heart rate? Like, take 220 minus your age (178 for me) then multiply by 60% for fat-burning (107) or 70% for aerobic (125). But I’ll be honest, now that I look at these numbers, I think I was spending much more of my time than I realized in the 80% range before now. I mean, I know when I went bicycling, I was routinely up to HR of 150.

So anyway, now, I have to recalibrate my efforts. It feels as if I have to work a lot harder just to get to the 60% mark (because I guess I was getting there too easily before), and I’m having a hard time with that. Jay is also feeling this effect, according to what he wrote about his running yesterday. Of course, his problem is on a much different scale from mine. He’s reasonably fit; I’m about as close to couch-potato as I can get.