Squeezing glutes on Deadlift

[giussepe20]

So my ass tucks in during my set-up and I get lower back rounding.

I have a question. Are you supposed squeeze your butt cheeks in during set-up and throughout the whole movement all the way up until lock out? Because all this time I've really only been squeezing them at the top when I lock out. Does that have anything to do with my ass tucking in?

[SuffolkPunch]

Read through the setup descriptions on Greg Nuckols How To Deadlift article. There a re few choices but the one you'll most likely use involves raising your chest and winding in your spine to pre-tension the core before your lift off.

I don't think you need to actively squeeze the glutes as they are a prime mover so they will be activated regardless.

[Garage Rat]

You need to be tight on on the start through out the whole body.
Creating tension equals strength and no power leakages through areas that are not tight.
You should be driving mostly through the heels which will activate glutes and hamstrings.
In the start position it's hard to get good tension on the glutes as the quads are involves on the first 1/3 of the pull.
When the bar gets to about the knees really squeeze the glutes hard and drive the heels through the floor.
Your ass tucking could have something to do with your technique on max weights.
Post a video.

[Radicalnotions]

Only squeeze the glutes at the top. At the bottom, you should feel tension in your hamstrings. If your ass tucks in, it could be because you're not hinging at the hips properly and instead are rounding your lower back.

[zGwild]

Your ass is tucking because of your hip position. You are set up wrong. Your hips need to be higher.

Record yourself and watch where your hips are when the bar leaves the ground. That is where your hips should be at the start of the pull. This should flatten out your back angle and get rid of the rounding.

watch these 2 videos

First will show you why different people have different looking deadlifts.
The second will show you proper setup

[DLandCheese]

When initiating the lift, concentrate on bracing your core while straightening your legs. When doing so, ensure that your shoulders rise at the same rate as your hips. Then, as the bar approaches knee height, push your hips forward while attempting to rotate your legs, from hip joint to ankle, laterally. Of course, your feet should remain planted and not rotate outward.