Sprint related drills/exercises will have the biggest benefit and in my opinion almost all of the benefit, the only slight benefit i would see to weightroom accounting for a significant portion of training is during times of bad weather were no running facility is available and maybe for the 55/60m dash, besides that sprinting and sprint related drills should be the main focus, lifting may have some benefit if you are plateauing on the track, but that is just my opinion not scientific in nature.
