Running - how to improve?

I'm 60 and can run 5k in about 35 mins. I found that more interval running - run 1k, walk 500m, run 1k - helped me with breathing, overall endurance and improved my speed a little. I generally run 5k two or three times a week.

Quick answer: you’re running too hard and you’d benefit from doing more brisk walking - where you feel like you’re faster than a comfortable walk, but can still speak full sentences.

Kudos to you, you’ve been pushing through regardless, so you definitely are capable of getting better. You just need to get the strategy right.

Longer answer: a 40 min 5k is 8 mins/km. Given your sex, age, that you’re a bit overweight and don’t have a long training background, I would generously estimate your VO2 max at 30 ml/kg/min. This means the 8 min/km running is likely above something called your aerobic threshold - the point where it likely gets uncomfortable to run. Doing more movement just below this threshold will benefit you.

I’d reduce the number of runs at your current pace from 3 to 1 per week and treat it as your higher intensity session. For the remainder of the week I’d try to increase the frequency of brisk walking. Ideally, brisk walk every day. We actually ran some analysis on Strava data and what separated the best runners from the rest -> it was clear that sports science was right: focus on increasing frequency (number of times you go out per week), distance (how far you go during the week) and then intensity (time below your aerobic threshold). Intensity is important, but not before you get these things right.

If you lower the intensity to brisk walks you should recover better and be fresher for the higher-intensity run with friends. Plus, each session should be more enjoyable.

The exercises that made you ache, you need to keep on doing them. As long as it's not pain just ache, they'll be doing you good. 3 times a week, work up to a harder level from a simple start. Good luck!

I’m in a similar position to you and I don’t think 40 minutes for a 5k is that bad!

I signed up to a free training plan from Runcoach, which is just two long runs plus a tempo run with some exercises (high knees, skipping etc) and strides (almost sprint intervals) every week.
I found out that the pace I have been doing my long runs is actually my tempo pace, so my long runs need to be much slower.
I used an online calculator and just put in the time for my last run. .https://runbundle.com/tools/running-training-paces-calculator

It seems counter intuitive to run slower to get faster, but it seems to be the thing to do.
I’d say don’t worry about heart rate zones too much, mine has come down a lot as I’ve got fitter.