Some riders push their hands down unto their thighs, holding the reins as to force the horses head down. It means you have to tip forward –out of balance- and brace your back. I have even seen instructors advising this. But if you need such force to get the outline, there is something very wrong.
The harder you pull him down, the more a horse wants to push his head up. If you use draw reins with force and you take them off, a horse will stick