So, I’m out of shape and I recently started using an exercise bike. I’d pedal for about 20 minutes and my heart rate would go up to about 130ish.
Trouble is, I also have a bit of a panic attack problem. I spoke to my doctor about it and she put me on a low dose beta blocker. Beta blockers slow down your heart rate. Now, when I hit the bike, my heart rate barely breaks 100, and I have to work pretty damn hard to hit even that.
Am I still getting cardio benefit from the workout? If so…how? I’m under the impression that in order for cardio to strengthen your cardiovascular system, your heart rate needs to reach a certain level, and that level is definitely more than 95-100 beats a minute. Am I wrong? If so, I’d be hugely grateful if someone more knowledgeable can explain how.
PS - Just FYI, I don’t enjoy cardio, and the reason I’m asking the question is if I’m no longer getting any benefit from it then I’m just going to stop. I’m not going to stop taking the beta blockers because in terms of my panic attack problem they’re an absolute Godsend, and I’m already on the lowest effective dose.
If you actively dislike doing an exercise you will probably stop doing it. So find something you don’t actively dislike; the only such exercise I have found is walking a couple miles a day.
Trouble is, I have bad knees (found this out recently when I started jogging). That pretty much limits my cardio to cycling and swimming. I love swimming but the nearest pool is a 20 minute drive and it’s always super busy. Cycling is unfortunately the least bad option. It may be that I get sick of it and give up anyway, but I’m pretty motivated to get in shape this year. If I can be confident my bike workouts are actually having a positive effect on my cardiovascular system then I’ll probably stick with it. I just don’t know how they could be if my heart rate only hits about 95-100 during a session.
I have a severe, untreatable form of heart failure, so I’m familiar with some of the literature about beta-blockers and “chronotropic incompetence” in that context, but … as a treatment for anxiety …?
I don’t see anything directly on point in the literature after a very quick search, but I think it’s reasonable to extrapolate from some knowns …
… and to infer that raising your heart rate is better than not, and that – while you may not maximize the benefit with beta-blockers (“BBs”) to the exact same degree that you could without them – you’d still be gaining some measure of the benefit.
Something … generally better than nothing. It’s probably analogous to you running a 15 minute mile rather than your previous 10 minute miles.
As the above article points out, start watching how much your heart rate recovers in the first minute or two following your exercise. That will give you some indication into your state of cardiovascular fitness and any changes you’re making to it by your (admirable) efforts.
I don’t have an answer, but share your question. For reasons, I am currently on 320 mg of Sotalol (not a beta blocker, but similarly suppresses heart rate). Now, when I run, I can’t get my HR over 90 bpm and if I don’t ease into that very cautiously, it feels like crap and I have to quit. My 5K time is 50% slower than last Spring. At that point, I typically ran at ~130 bpm, which I could maintain for over an hour.
That said, 130 bpm is pretty firmly in my “zone 3”, so I’d been consciously trying to ease it down for long runs. 90 bpm is ridiculous, though.
I see both my cardiologist and my electrophysiologist in a little over a week and will be pressing them on this to reduce or eliminate the Sotalol. I’ll report back what they say (although neither demonstrates much competence with exercise cardiology).
Thank you for the correction. It was characterized to me as being different, but my current cardiologists have given more than a bit of evidence of being dumb-asses.
Short version before diving into the weeds: yes you are still getting benefit and in your specific context using a “rating of perceived exertion” scale (RPE) is going to be a better proxy of how hard your cardiorespiratory system is working (and therefore the benefits) than heart rate based on a formula determination of heart rate max.
So into the weeds!
First it wasn’t easy to find the study that best addresses this because the first batch of articles was more focused on the context of those on beta blockers after heart attacks and having more concern about individuals working too hard, rather than than not hard enough!
Second, heart rate is just a proxy measurement for the system work. This article goes into great detail but to a large degree the heart compensates for the slower rate by increasing the efficiency of oxygen delivery per beat (as measured by oxygen pulse) so more work is being done at a lower heart rate.
Over the 60 years since the introduction of beta blocking drugs there have been a very large number of studies, which have anticipated but failed to find meaningful impairment in maximal exercise performance, in different groups e.g. healthy subjects (Mitchell et al., 2019) , athletes (Fikenzer et al., 2020), patients with coronary artery disease (Eynon et al., 2008) and patients with hypertension (Reybrouck et al., 1977). All these and others have shown that oxygen uptake was maintained. This study failed to find any major negative consequences on exercise capacity and symptoms by taking beta-blockers, thus confirming previous findings. The novelty of this study is that the reduction in heart rate was accompanied by an increase in oxygen pulse. … … The heart rate response was 18–19% lower due to the physiological effect of beta-blockers. This was accompanied by a higher oxygen delivery per heartbeat of 19.5% (VO2/HR: Oxygen Pulse). Whether this was due to an increase in the stroke volume and/or arterio-venous oxygen difference is of interest but could not be definitively answered.
I’ll add in a speculative wondering. In your context a formula calculation of HR max is wrong. The beta blocker has made your HR max much lower than that calculated number. I would be unsurprised if going by percent of TRUE, tested by graded max effort testing, max heart rate, was still a good guide. But I am NOT advising you do that.
This past summer I noticed that, after a run, my heart rate would stay above 90+ even after hours. I’m not in athletic shape yet it ought to drop to something 75-85.
I had previously been on 50mg of Metoprolol from 2000-2015. Doctors in Ireland would fill that prescription no problem even for 128/85. In the UK one said “that’s too long to be on Metoprolol” and I went onto onto Enalapril - an ACE-inhibitor. Occasionally, while trying to sleep my heart would be thumping fast and loud. Chewing on a bit of metoprolol would allow me to sleep.
The doctor I saw in Summer pretty much disposed of the notion of “too long” and back on Metoprolol - the tartrate version that I take 50mg in morning and 50mg in the evening.
Within a few hours my pulse had fallen to 70’s and after a run would get there soon enough.
A short anecdote: The last doctor I saw in the USA at a hospital asked me how much Synthroid (aka Levohyroxin I took) and I said “175 micrograms” and she looked at me like I was some drug addict and said “That’s a lot”. I was in for a broken collar bone else would have shrugged yet did say "would you like the name of my *endocrinologist? (from when I had gold standard insurance). They ran the tests and 175 it was and has been since. It’ll never go down.
I know Metoprolol is banned (and looked for) in Biathlon where you go from skiing to shooting at targets as fast as you can. Synthroid really has no good misuse - you will not bulk up or lose weight. Go for caffeine or something, err, north of it if that’s what you’re after.
Nah. Not even for a general population not on beta blockers. Of course the number is only in context to your HR max but even training in low zones, including 1 to 2, improves CR fitness. Just takes more time.
But again HR is a proxy for oxygen consumption which is what drives the positive adaptations. And it is a poor proxy when on a beta blocker.
Thanks for the information. It was useful and interesting! Sorry to hear about your health issues. Sending you best wishes!
Thanks so much for this! Your entire post and linked articles were very useful. I appreciate you taking the time to find all this out for me. Dopers are awesome!
I saw both my cardiologist and my electrophysiologist today. Both agreed that I should stop the Sotalol. The EP said to stop it abruptly, even though the package insert says that can be dangerous. I am reducing more gradually and am waiting to hear from the cardiologist, who thought the EP would have me titre it. I’m skeptical of both of them, but I don’t trust the EP as far as I can throw him. I need to find a cardiologist who is attuned to exercise, because neither of these two are.
Having tried to exercise for several months this way, I think the RPE picture sounds reasonable. Unfortunately for me at this dose, I only ever either get an RPE of 9 or of 10. If it’s “only” 9, then I can finish my run and feel like I got a workout. If I start infinitesimally faster (or on a slight uphill or into a headwind) it’s immediately a 10 and I have to quit. I think on a more moderate dose, it should be practical to use RPE to just run slower. In my case, the dose was kept stupid high for no good reason for far too long.