I always start training with a warmup or (sometimes a stretch). But if you wanna give them sprint, then I guess do some very easy attack/defence drills (1 or 2 in total) then let them sprint.
Some combinations also work extremely well, always set up the schedule like an in-game scenario. The opponent takes a corner (which is a cross, actually). You head it out, and one attacker hits the ball hard to the other half. Luckily it (intentionally) went to your ST and they have only 2 defenders.
Thus, it makes sense to use a pattern of set piece delivery-defending crosses-fast counterattacks.