Runners don't need to strength train.
A lot of runners, especially the old school ones believe strength training is not necessary for running. Maybe this comes from seeing the elite long distance runners as skinny men going really fast. What a lot of people over look is that these guys are not light because they don't eat, but they rather have really dense muscles which have become really efficient at processing energy through lots of work. If you ever meet an elite runner, though, ask them if there's any strength training involved and you will know the truth. Having a strong support for your frame will help having a right posture, endure the impact with more ease, and prevent injuries over the long run (pun intended)