for endurance on the field, work your calves! the more apt your calf muscles are to quick reaction will make the lead off of sprints faster and will help you to be light on your feet. (: it worked for me, i was the speed of my high school team and when i got injured sophomore year, my physical therapists had me work my calves a lot so i could catch up to speed with our work outs.
Here you go anon. Thank you!