Quote Originally Posted by KnottedYet View Post
Are you the sort who can go forever and not run out of steam, or are you a little bunny rabbit who goes very very fast? When you were in track, did you run 50/100/200 m, or were you in the 400m and up?
I am most definitely a fast-twitch gal. I ran the 200 and the 400 quite well in high school track but I was barely able to run 2 miles straight even though I was in tip-top shape.

Right now if I try and go for a run my HR hits 170-180 within the first 2 minutes of a run (and that's on an easy run) and stays there. My resting HR is around 78. My HR does recover fairly fast so if I go for a run I have to alternate jogging and walking.

However, I've been biking for a month now (almost at 200 miles total!), and I am able to do 15-20 miles averaging 12.5-13.5 mph without any issues. My HR generally sits around 130-140 most of the time and gets up to a max of 170 when I'm really pushing. I rarely feel out of breath unless I'm really pushing hard for a long time.