I apologize for showing my back. However, to give the best illustration
of this exercise, I felt that this angle would be better understood. JVA
The "Hack" Squat is one of the oldest, yet still a very valuable assistance exercise, in Iron Game circles. Long before the invention and use of squat stands and machines, this exercise gained notoriety over 100 years ago, when old time wrestler and strongman, George Hackenschmidt introduced it into his training.
Also called the Hack Lift , or at times the Behind The Back Deadlift , this exercise is an excellent assistance exercise for both the squat and deadlift. However, body leverage and flexibility does play a key role in the proper execution of this movement!
To perform a Hack properly, you first stand with your feet about shoulder width apart with a barbell behind you. Stand as close as possible with your achilles tendon (heels) of each leg touching the bar. Then squat down looking up at a spot on the wall about eye level across from you when you were standing up. Try to keep your back as straight as possible.
Now, push off with your legs while concentrating on bearing the weight down on your heels. Don't push off with the weight forward over the balls of your feet. As the weights leave the floor, concentrate on keeping the bar close to your calves.
When the bar reaches the height behind your knees, you then pull your hips forward while simultaneously pulling your shoulders backward. This will be impossible to do if the weight is not over your heels, and if your back is rounded forward, because the rounding of one's back forward puts the center of gravity of the bar forward. Thus the bar will run into the hamstring area preventing the upward travel of the bar.
The two above illustrations shows incorrect positioning! Note the subject's hips
are too high at the start, to where he's reaching back instead of straight down.
This then creates a situation where the bar swings forward into the subject.
Now, although shorter armed people are at some disadvantage leverage wise, I am not convinced that such leverage makes this movement impossible. If you have problems with balance on Hacks, try starting at the top or finished position doing an eccentric movement first, by squatting down and then back up. Remember, when the bar gets below the height behind your knees, just slide it slowly down your calves. Stop with the bar just a few inches below your knees until you get used to going lower.
Another alternative, to get used to this exercise, is start higher up with the barbell sitting on blocks or the pins in a rack. And remember, keep your shoulders back, with your back straight, and don't forget to pull your hips forward as the bar passes your hamstring area.
Now, I always recommend using a Hook Grip on Hacks. This is the best way to hold onto a barbell. Sets and reps are up to the individual. Personally, I like the 5X5 approach here. Also, for a warm-up prior to starting my Hacks, I recommend doing a set or two of light full deep squats.
My preference is to power clean a light weight and then do about 5 to 10 full deep front squats to stretch and circulate blood into the knee area. Then I do my 5 to 6 sets of Hacks.