It has become fashionable that the first thing people do when they get to the gym is lay down. In the name of prehab or rehab they enter a facility entirely designed for movement and instead of moving they...lay down.
"I have to warm up" they profess.
They either forgot or never knew the first few sets of any workout are the warm up. Those sets are of things like squats, presses, and rows. Not holds, foam rolls, or muscular isolations.
In those sets you grease the groove of the movement. If it feels good with little or no weight you gradually start adding. Over the course of a few sets and minutes you work your way up to a weight that's appropriate for a 'workout.' Seem simple?
That's because it is. We want exercise to be more complex than it needs to be and as a result we started warming up for our warm ups with more physical therapy esque exercises and damn near couch like behavior. It's dumb and a waste of time. If you're hurt and need rehab that's one thing. Exercise itself is prehab for about every ailment we may need rehab from so justifying it with that is silly.
If you do anything but move when you get into the gym you're doing it wrong. Certainly don't lay down. And for your own sake take a few sets and minutes with your first movement to get yourself acclimated to work.
Your warm up doesn't need a warm up.