Good question! The meta analysis advises that for the first 8 weeks, so as you are building up to sprinting 3 times a week, your rests should be active. But this is a level 1 on the perceived exertion scale, so very very light movement and 50-60% of your max heart rate. For me this would be about 97bpm, which would be a walking pace.
Then once you have built up to maximum volume, it suggests that you rest completely between sprints.