I'm a High School Senior now, and I've been wondering a very important question for this year. How much mileage can a person do until they lose their fast twitch? I've done about 350 mile this summer, just base. A couple of strides ,a fartlek, and hard runs, but that's it. I've probably averaged a little over 45 miles this summer, with this week being at 70. Is that too much for a High Schooler? I average my runs at about 7:10-6:20 pace, sometimes dipping under 5:40s if I'm feeling good. Will I have lost all the speed I gained from track, or come back stronger?