Warm up by doing 10-20 minutes on the bike first, then go straight to squat. I don't like to pre-exhaust my legs before squats, why take away from the best leg exercise? After squats I will superset extensions and curls to burn them out, or do deadlifts. After that I can't walk anymore.
Properly performed, which they seldom if ever are now-a-days,
using leg extensions immediately prior to squats could be a god-
send, depending on how you are wired.
That sequence of exercises is capable of making far greater inroads
and will stimulate your quads in a very safe and effective fashion
without breaking your back in the meantime or subjecting it to
potentially dangerous loads. The pump / burn and the resulting
growth if you have it in you, must be experienced to be believed.
And for those people who have trouble standing up after a set of
squats . . . well . . . you will have problems laying down after doing
But you have to know how to do them, you can’t over-do them,
and you must check your ego at the door. (Not many people are
capable of all three of these things.)
leg extensions are a complete waste of time and energy. you want to do another exercise after squats then throw in a set or two of front squats.
If this means anything to you . . . I wish you could have seen
a guy I used to train with eons ago. Never did ANYTHING, ever
for his legs except leg extensions, and he did more sets of them
than I cared to count. And he had huge, thick, cut, vascular
quads. Probably the best quads I had seen on a non-Pro.
So while they might not “work” for everybody, they sure as hell
worked for him.