Hi Mammer, I used to be a distance sprinter. Nutritionally I would intake more carbs than protein and carb load before a race. Heavy weight training will not harm your aerobic performance. The extra strengthening of your joints, tendons and of course stronger muscles will help your running speed. If it is your endurance you are mainly having trouble with then give that extra attention to endurance training. I liked inteval training. Now I'm lucky I have always had great endurance.... I do believe a lot that helped me was breathing....I would practice deep breathing, expanding my lungs ect. As with anything the more you do it the better you get. Try getting on the treadmill at a fairly steep incline and run. Keep your pace constant. After you "level out" with that speed it up and go faster till you level out again. I also would do traditional short sprints for power. I hope this helps some.