Re: Marathon/Multi Sport Training
It probably depends a lot on your body and background.
I ran my first Marathon on a modified Hal Higdon's Novice... because of my schedule, I only followed his long run progression, but did it on an average of under 3 runs/week, and about 15-20 miles/week. My target was just to finish, and I did it in 4:40... hurt a lot, but the pain was over in just a few days. So... it's possible to finish it in one piece, with a low mileage. For my 2nd marathon, I trained more, about 3-4 runs a week, peak mileage 20-30/week, and was ready for a 4h marathon, but got sick the day of the race and barely made it to the finish.
I'm not an expert here, but my question is: on a 12-16 miler, if you still feel strong at the end, if you can throw in a few miles at tempo pace, if you can pick up the speed on your final mile, then I think the current weekly mileage is OK. If it doesn't feel that good, then you definitely have to increase the mileage but throwing in longer runs.
Chris