Are you asking immediately after a CrossFit workout or are you asking if CrossFit will help you with running 5k’s?
Experienced CrossFitters can usually wait 15 minutes after a workout and tackle a 5k but not at the same intensity as if they were fresh. CrossFit will most definitely help your 5k time tremendously in the long run. The purpose of CrossFit is to raise your overall fitness level, hence raising the physical potential for any individual to excel further in their sport, even for running.
