I’m getting close to setting PR at 50+. I ran 16:40 5K as an undertrained runner in high school; it’s still my PR. Last year I hit 17:40 at age 49. I’ve upped my training considerably This year and will have a decent shot at sub-17. I should also get lifetime bests as a 50 year old because of weak PRs in the 10KM (36:30), half marathon (1:21 set at 49 years old) and marathon (3:09 set at 48 years old).