I'm 32 and hadn't run since high school. I've been back running about 4 months. I can tell that I keep getting faster because my everyday running paces that used to feel hard now feel easy. What used to feel like a tempo run, now feels like an easy run
After 2 months, I ran 10k and it was near 100% effort. I treated it like a race. 47:39 worked out to 7:40 pace.
After 3 months, I ran a 10k on a very hilly course in 40:40 6:33 pace.
Earlier this week, after 4 months, I ran 10 miles at 7:00 pace with relative ease. It felt fast but nothing like race pace. I was not exhausted after.
Is there a rule of thumb of how long it takes to get near peak shape? Like to where gains take much longer to achieve?