Lifting as a warm-down from sprinting

Most of the time we finish our speed work and go right into the weightroom. Should we warm-down after the speed work before the lifting or will the lifting serve as a warm down of sorts followed by static stretching and self massage/treatments. It seems to me we should hold off the warm down till after the lift, but most of my sprinters dont feel the need to warm-down after a 45min lifting session. Are their muscles stretched enough after deep squats?

Scott Weiser