For some time now I’ve been aiming to do my endurance training at my MAF heart rate. MAF stands for Maximum Aerobic Function, and it’s the heart rate where you’re producing the maximum output without having to use anaerobic systems. Although the MAF formula just produces an estimate, there’s quite a bit of data to back it up.

If you do almost all your training at MAF, you’ll get better (run faster) at that heart rate. The idea is that you first do that, and only when your performance plateaus do you need to start doing any sort of speed work (and then not much of it).

As I say, for some time I’ve been aiming to train at my MAF heart rate, but it’s a low enough level of intensity that I’ve persistently had trouble not running too fast. I have a heart rate monitor, but it’s not very useful during a run, because my heart rate is displayed on my phone, and I don’t want to run around carrying my phone where I can see the screen. The upshot has been that I’ve inadvertently done a great deal of my training somewhat above my MAF heart rate, which rather defeats the purpose.

To get a better grip on my MAF training, I finally broke down and bought another heart rate monitor, which displays my heart rate on my wrist so I can check it while I’m running. It also has an alert function, so I can set it to vibrate if my heart rate goes above some value. After looking around a bit, I settled on the Mi Band 4 (which is available for cheap because the Mi Band 5 is now out). It does the thing I want well enough. (It also does a bunch of other stuff that I don’t care about, and some things that I do care about (sleep tracking), but that I do some other way, such as with my Oura ring.)

After a shakedown run a few days ago, where I spent a lot of time trying to figure out how to use the device the way I wanted, today I went out for a run where I tried to use it for some proper MAF training, and I think I was very successful. I probably only spent two or three minutes (out of a 51-minute run) with my heart rate above my target.

This very easy run was nice and gentle. Sitting here at my computer maybe an hour after I got home, my heart rate is already back down to just 64 bpm, which amounts to a surprisingly complete recover. After a run only a little bit faster, I’d expect to see my heart rate stuck in the 70s for several hours.

Now to see if regular training this way produces the speed gains it is reputed to.

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