Lately I have been wearing 10 lb ankle weights on each leg, 8-12 hours a day. I also do leg lifts, 30 reps a day, and 100 knee lifts a day along with any other lifting I do while I'm sitting around. I'm looking for a bit more leg strength, but mostly I'd like to increase my speed. I'm worried that the wrong exercises will bulk up my legs and hinder my speed. What are some good leg exercises to help myself get faster?