Just thought to add this over here as well, in case some are looking for ideas. PL's are using sleds like football players, to improve speed and explosiveness. This thing is a LOT harder than you would think, so one sprint will have you gasping! One old Tire One eye bolt, 3/8" One wood block inside for eye bolt nut One scrap piece of 2x10 inside Some old cement weights or rocks Tow strap or rope Weight belt or cartridge belt