Aerobic Threshold With Beta Blocker
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I current take a beta blocker for a medical condition which can lower the heart rate. I am the stage where I want to determine my aerobic threshold, per the test found on Evoke.
I wanted to see if someone had any experience with this and how it effects training, in the long term. I have tried the aerobic threshold test twice, the first test the stairmaster rate was to low, so when I attempted it again I raised it’s rate by one, and it was to fast. I complete my cardio with box steps, as I have patellar tendonitis so running is not an option.
I appreciate any feedback.
I can’t find a way to edit my post, but wanted to add some more information.
I have included the output from my latest cardio session, showing my consistent HR. This was done with box steps, and holding a consistent 100 ft of vertical gain per 10 minutes (1200 ft total). If I use this then my aerobic threshold is about 125 bpm, which is below the average which I believe comes from my beta blocker use.
Great question, and one which I am not sure has an easy answer. The first thing I will ask is whether you’re on beta-blockers for a cardiac or a non-cardiac issue (and I don’t expect you to divulge any specific medical information on this forum), because this can obviously influence the exercise prescription. If you’re coming back from a heart attack, for example, then caution is needed at higher intensities.
Coming back to your question, and assuming that you are healthy from a cardiac standpoint, HR becomes a far less reliable indicator of exercise intensity when beta blockers are being used. Studies have also shown that amongst individuals, the response is quite individual, and the HR response to exercise is non-linear, and therefore there is no easy or reliable formula to correct for beta blocker use. It likely depends on the condition being treated, the beta blocker dose, time of day etc, etc.
None of this helps you however, but in general, the HR effect will be blunted, so if your AeT HR off betas blockers is 135 bpm, then it will very likely be lower on beta blockers foer the same metabolic intensity. That’s about all that one can say, and the drift test will not be accurate.
RPE (rating of perceived exertion) is probably more reliable, especially if you are very experienced and in tune with your training intensities, but some people struggle to gauge their RPE, and other things can throw it off.
The only way to reliably determine your thresholds would be in a lab, with either lactate determinations or gas exchange. These can be costly tests, and aren’t available everywhere.
A couple of other quick points: (1) the chart that you added above looks to show almost no drift to my eye (I could be wrong though on that) but as I have said, I would not rely on a cardiac drift test to determine AeT HR.
(2) There is some suggestion in the literature that the long term training effect whilst on beta blockers is blunted, though there is limited published work on this. Is there an alternate treatment? Some patients take beta blockers for migraine prevention, for example, and there are other effective treatments now for this condition.
(3) Have you applied the MAF HR formula to your particular scenario? I am somewhat interested in where it would put you (purely out of curiosity). Do you have any thoughts on RPE at your ‘calculated’ AeT? Does it feel sustainable?
(4) Lastly, remember that ‘all training works’. Some is just more effective. So this may be a moot point, and I do not know what your goals are, but there is rarely anything negative to say about a large amount of low intensity work!
I am interested in whether any of the other coaches on this forum have encountered this scenario, and how they handled things.
I have no cardiac issues and have been preparing for a Rainier attempt for two years. I begin the 16 week training plan this March, but overall have been using the TFNA training logic for the last two years. This is why I am spending about 4-8 hours a week training, with a lot of “Level 2” aerobic box steps, and I have been hiking on various hikes.
The beta-blocker is for a movement disorder, which you can probably Google “Beta-Block & Movement Disorder” and find out the condition I was born with. I don’t need them, but use them to control my movement disorder. However, as I have been training with them for the last two years, I think it makes more sense to continuing my training and attempt with them.
I need to reread your reply to ensure I understand everything, but I will reply with some answers.
Using the MAF HR Forumla, my threshold is about 147 bpm. I know this probably isn’t the best technique, but when I train I am using my Garmin Fenix 6 to track HR/Stats and have been using the default heart rate zones. I know Scott is a big fan of nose breathing, and using this technique I can nose breathe at a higher HR than what is included above, probably around 145 bpm. However, that HR does not feel sustainable which is why the MAF HR formula does not seem correct to what conditioning with beta blockers.
As for RPE, I can say the 125 bpm that you can see in my workout above is sustainable, I am slowly increasing time each month. But at this point I can keep that pace for 90 minutes and potentially longer.
Typically with MAF there is an adjustment based on health or medications, so I would definitely make a subtraction; by how much though is anybody’s guess, but a minimum of 5. Nasal breathing is another good option here, especially in the aerobically fit, which it sounds like you are, so I’d guesstimate that your true value (on beta blockers) lies somewhere between 125 and 140. Without more detailed testing though, it is hard to know, and as I say, a high volume of easy training is never a bad idea!
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