Since 2015, when Christopher McDougall’s Natural Born Heroes introduced me to the work of Phil Maffetone, I have not tried to work on running faster. Instead, I have focused on building a really solid aerobic base. Specifically, I have tried to run at a speed that kept my heart rate near 130 bpm (which was the MAF heart rate I came up with back then).

The theory is that, by training at that heart rate, you will gradually increase the speed at which you can run at that heart rate: You get faster at that particular level of effort. Basically, you persist with that—doing your runs at that heart rate—for as long as your speed increases. Only then do you add speed work (intervals, tempo runs, etc.), and then only as a few percent of your training.

In my own rather casual way I took all that to heart. I never did much speed work anyway, but I was happy to just not do any while I waited for the magic of the MAF system to kick in. But it never did. For the past five years I’ve been running very slowly (call it a 15-minute pace) at a nice low heart rate, but I’ve seen none of the gradual improvement that was promised.

I can’t really call it a failed experiment. I’ve enjoyed these slower runs. I’ve largely avoided injuring myself. I’ve built a solid aerobic base. But I’d like to be able to run faster, and following the MAF system doesn’t seem to have done the trick.

So I’m going to gradually ease back into running faster. I’ve done a little sprinting right along (more as strength-training for my legs than in an effort to work on running faster), and I’ll boost that up just a bit. But the main thing I’ll do is just run faster whenever I feel like it.

For years now, I’ve made it a practice to try to notice when my HR goes above 130, and ease up whenever it does. I might still do some runs like that—it does help me refrain from going out too fast and ending up exhausted halfway through a planned long run. But I think I’ll go back to just intuitively running at whatever pace suits me in the moment.

I did that today, and ran 3.16 miles in 43:16, for an average pace of 13:38. Not fast. But I wasn’t trying to run fast—I just quit deliberately slowing down anytime I noticed my heart rate was over 130. For this run my heart rate averaged just 134, so I wasn’t really pushing the effort. Maybe I can still run 12-minute miles!

(By the way, I wrote about Christopher McDougall’s Natural Born Heroes in a post on it and a few other human movement books.)