Running

I’m a casual runner. Not very consistent. In 2022 I was running more and aimed for speed for 1-4 miles usually. But my heart rate was always in zone 5. 180+. Some runs were 90% in zone 5; obviously not safe.

So lately I’ve gotten back into running and I’d like to get close to what I was doing 4 years ago, but with a safer heart rate. I’m assuming I can simply run very slow 11-minute miles and keep my heart rate below 160. But perhaps you have some experience or advice on how to maximize efficiency? I’ve seen experienced runners doing sub 8 minute miles for 10 miles with an average of 140bpm. That’s so out of reach for me right now. I’m 36 and my max HR is currently 194 based on recent activity I guess.