First distance run focusing entirely on BPM

I had read somewhere not that long ago that running at a lower speed in order to keep your heart rate at an "optimal" level is the way to build endurance. I think that most people probably just go out there and try to run as fast as they can without ever looking at their heart rate and trying this is likely why a lot of people get frustrated and quit.

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_{it is still very cold here}

I have a ton of different tactics for my runs but recently on a number of occasions I have felt like I was actually losing progress even though I was going more frequently. I read a lot in my efforts to try to improve and one of the things I read was to gain endurance and improve cardio in the most effective way, one needs to get into zone 3 and stay there for a long period of time. So this is exactly what I did yesterday.

I didn't have a particular distance in mind, the only thing I was trying to do was to constantly be looking at my watch to ensure I was staying in zone 3 and not even entering zone 4. I messed up and ended up in zone 4 pretty regularly but was able to slow down and get myself back into 3 for most of it.

Aerobic state is meant to be the "best" state for gaining endurance for distance runs. The science part of this in a shell is that a person will be able to continue doing exercise, whatever that exercise is, for a longer period of time if they remain in this zone. Over time I suppose the idea is that your cardio system gets stronger because of this sustained strain, even though it is a slight strain.

I CAN run faster than this and I am NOT pleased with a 8:30 km pace, but this is what I need to stay at in order to remain in zone 3.

km 11 doesn't really count because that was mostly me standing somewhere trying to get my finger dry enough to turn off my timer. But these certainly aren't impressive km speeds.

Is this effective? I don't really have any idea but I tend to believe some scientists when they talk about it. I do know that this run wasn't really all that taxing and I never felt spent or gassed out, in fact, I felt like I could have done another 10k but there was a small issue developing with my knees even though I think much of that was psychological.

I have always said that one of the most important aspects of exercise is that you don't end up hating it and honestly, this was not a bad run at all although I probably looked like an old man shuffling down the street, which I suppose I kind of am since I am in my 40's. I did get some joy out of when a couple of other runners whizzed by me like I was standing still only for me to catch back up with them later because they couldn't maintain the speed they were doing. Perhaps they were doing some sort of interval training which, from what I have heard, is also effective.

No matter what you do for training there is likely someone out there with a YouTube channel dedicated to telling you how you are doing it wrong.

For me, I am going to stick with this one for a while because I found it to be easy plus I like the idea of having an elevated but not uncomfortably heart rate for 90 minutes or so.