Ever since my aortic valve replacement in 2017, I have been on the beta-blocker metoprolol. This is mostly to prevent possible heart arrhythmia but also helps control my blood pressure. It seems to be working fine and I have no noticeable side effects, other than my heart rate doesn’t seem to go up quite as high during exercise. Wednesday showed its effects more dramatically. I had finished my prescription bottle and Wednesday morning I could not find the replacement bottle. I usually take it first thing in the morning before any activity. I decided to go on my ride anyway and look for it later. Wednesday was scheduled to be a harder ride, a long brisk tempo ride followed by an interval session and on-bike strength training. I wore my chest strap for heart-rate monitoring, which I know is accurate.
During the tempo portion of the ride I noticed my heart rate was more then 10 beats higher than I expected, approaching an average of 120, despite the fact that my perceived level of exertion was similar to recent such rides, and I passed the “talk test” so my breathing wasn’t too labored. (so people don’t get concerned that I’m talking to myself going down the road, I use the alternative of reciting the alphabet). Then during the interval session I noticed I reached heart rates into the 150s, which I haven’t seen in a while. I found the replacement bottle after I finished the ride and belatedly took my dose. But this incident planted a seed of curiosity. I noticed the bottle says to take it “in the morning”, not necessarily first thing in the morning. Researching on the web, I could not find any reason why it is not OK to exercise early in the morning and then take metoprolol. It just seems to be a good idea to take it the same time each day. So I will start taking it consistently later in the morning after my workout.
I was also curious about what is known about it’s effect on athletic performance. It is mentioned in this video by a renowned cardiologist in the UK that beta-blockers like metoprolol impair performance by keeping heart rate lower during exercise. This seems logical. If I’m doing an interval and my legs are screaming for oxygen, it seems I might not be able to go quite as hard if my heart rate remains in the 130s instead of the 150s.
Lately I’ve been researching topics like this on Google’s Gemini. If you click on “deep research” in the “ask Gemini” box, instead of just answering your question, it will search a bunch of relevant sites on the internet, then go through the results and make a report. This is a fun use of AI. So I did this, and typed in “Metoprolol’s Impact on Athletic Performance”. It came up with this detailed report, from which I learned a lot. It does appear that metoprolol affects endurance performance, such as a slight lowering in maximal oxygen consumption (VO2max). My taking metoprolol is necessary for the prevention of possible arrhythmia. But for anyone who is taking this or another beta-blocker solely for preventing high blood pressure, there are alternative blood pressure medicines, discussed in the report, that have much lower effect on performance.
There is also a good discussion about beta-blockers and exercise on this website. The bottom line is it is perfectly safe to exercise vigorously while taking metoprolol, and it doesn’t seem to matter whether you take it before or after, as long as you take it the same time each day.
I’m not really worried about some slight impairment in performance. And since I’ve been on the drug since 2017, and mostly interested in competing “against myself”, all my recent performances I’d be comparing against were equally affected.
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