I've been running for about 3 years now. My weekly mileage for a couple of years have been in the 30 to 40 mileage range. Last year after my first marathon, I got really serious about my running, and ramped up my weekly mileage to the 50-60s as I geared up for another marathon. I'm currently now running around the 70-80s with a one or two 12-15 milers during the week in addition to a long run sunday and easy doubles during recovery days.

My 10k time is mid 35's with my last marathon being around 2:45.

Based on my recent races, I think I may have hit a plateau or a point of diminishing returns. I don't race often but usually once every couple of months to test my fitness. I haven't seen much improvement on my shorter distance (10ks) times and am beginning to wonder if I am being to aggresive with my milegage.

For those high mileage runners out there (what I consider running over the 70s range), how long did it take you to work up to that level?