If the efforts are 600m and the recoveries are 4 mins, either the intention is that you go flat out during the reps and run v slowly to recover (which you certainly should do in 4 mins), or that the reps are not absolutely flat out and you keep going at a reasonably steady pace for the 4 mins. Depends a bit what you are trying to achieve. That sounds like a very short rep with a very long recovery unless you are an 800 metre runner or something.