Hey guys, I started football this year as a sophomore in high school.. i've always wanted to play but was afraid I was too small. Eventually I just decided to do it and here I am. Anyway, I can run miles long distance at pretty descent speeds and have no problems but when we did sprints in football I just couldn't take it. It was horrible.. I often threw up even from small sprints because once I felt like throwing up and kept pushing myself it was enevitable. I have a heart condition in which one of the valves sending blood to my lungs to be "reoxygenized" lets some blood flow back into my heart making it less efficient. I don't know how much that contributes to my problem since I can run long distance fine. Anyway, I just really have no Idea what's going on with me and how I can fix it. I really like football and want to get better but I get so tired so quickly from the explosive sprinting I can barely take it. If I don't change this I don't think I will be able to take the physical strains of varsity/jv football next year.... does anyone have any advice?