Hack Squat - Use Heels or Ball of Feet?

[bbfitness101]

Let's assume we want to target just the quads.

Some sources say drive through with your heels, others say use the ball of your feet. Will using the ball of your feet cause strain on your knees and ankles or is there a safe way to do it that way?

[etet1919]

I've never used the balls of my feet on the hack machines or any other type of squat (I'm not referring to split Bulgarian squats, where your back leg is placed on the balls of your foot). You have to drive from your heels!

[Garage Rat]

Drive through the balls of the feet placed slightly lower on the platform.
Heels may come up a bit depending on the angle of the platform.
Check out videos of Tom Platz doing hack squats.
While i don't recommend his style unless your an advanced bodybuilder his style is totally a quad emphasized movement.
With this style the knees will come out over the feet similar but not the same as a sissy squat.

If you go with feet towards the top of the platform driving through the heels and leg are in a 90 degree angle for the most part glutes,hamstrings and quads take much of the stress.
Also would control the movement and not"dive down"each rep.
A controlled push feeling the quads doing the work instead of momentum.

[coeur]

Not OP but here for hack squats

I’m doing barbell/no platform and my chest kinda caves in at the bottom, and of the videos I’ve watched this seems common... but how much is too much?