Just saw a post by @Sushi about using a beta blocker to lower heartrate so as to tolerate some activity, and I have wanted to look into this for some time. I was prescribed a beta blocker in 2014 for hypertension, and ever since then I have wondered how the reduction in heartrate should be treated when trying to estimate my anaerobic threshold. Should the formula to estimate this be adjusted to take account of the beta blocker, or can we assume that the new heartrate can be treated in the usual way in the formula? So basically, if the beta blocker means that I appear to be able to tolerate more activity before reaching my maximum permissible heartrate, can I trust this or do I need to adjust the maximum permissible heartrate downwards? From experience, I do seem to be tolerating the usual maximum permissible heartrate since starting the beta blocker, but have not been measuring it very often. (I get very little PEM.) Also, others have said that the formula is 0.6 times (220-age), but I have queried whether the '0.6' applies to someone whose function is 0.6 of that of a healthy person, so should be adjusted according to our individual activity levels. See this thread for discussion of these.