Yes, I probably could have run today after a 15 miler yesterday. My question is, will it help me race faster 2 months from now?
I am banking on the answer being no, but I guess that depends on how much damage my leg muscle fibers have endured and the length of time needed to recover. There is a time and place for overstepping the boundaries of fatigue, but the day following your longest run of the week is probably the best time to lay low or do something else. Intuitively, I like to use 2 hours as a threshold for not running the next day, but that doesn't mean I don't cross train. I feel surprisingly good on the bike the day after a long run!
It's a constant dilema among serious runners- what's more important- a higher weekly mileage total or sacrficing some easy miles in hopes of turning in an extra quality workout? Normally, if I can bounce back with a good session on Tuesday following a Sunday long run, I think I've made the correct decision.
Check out Rethinking Junk Miles- A Fresh Look at Recovery Runs by Matt Fitzgerald