Running is never enough to get better at running. This is why the Runner Strength workout focuses on the tendons and ligaments that power the lower body. Used for absorption of impact vibrations from running and the preservation of energy in each step, a strong lower body makes running a far easier physical activity than it has the right to be. If you truly want to outrun the Zombies, when the Apocalypse comes, then this has to be a workout you come back to often.