Go to a track and do 400 meter intervals. Run them at about 90%. Then walk 400. Repeat. I'd worry about injury with shorter distances. And with the required work/recovery time i dont know if this is an optimal workout for a body builder. Unless you are an athlete who still competes in their sport - football, bb, mma wrestling, soccer, badmittin, (Tiger Woods extracuricular sports) . If your really feeling stupid, only walk 200 and repeat.