I found that weight training my legs hurt my knees no matter how light I went. So I focus on torso and arm workouts. My sprint improves greatly when I have a stronger back, and I know I'm getting in form when my stomach muscles hurt after a sprint. So I work on both of those.

Dead lifts - for lower back.

Crunches and whatnot - for stomach

Arms - for pulling up on the bars - I lift so the bar goes fore-aft, not left right, so it's more like the drop position of the bars.

Shoulder area - for strengthening your collarbone. I did this as soon as I learned it might help.

Lats - for pulling up too.

However, all the lifting in the world won't make you have more endurance. Lifting gets you power, and if you do plyometric type workouts, you can gain speed. You have to do the aerobic type work in some other way.

cdr