Unlike a regular split squat where you attempt to push close to half of the weight load with the back/rear leg, to do the Bulgarian split squat you use the rear leg only for balance as the forward leg does the bulk of the work. To do this exercise, you can use a barbell for added weight and control or work without it. If you use the barbell, place it on the front of your shoulders like you are going to do a front squat or behind your neck, while placing one foot well out in front of the other in a staggered position with your rear foot placed firmly on top of a bench or box no higher than 18″. Make sure that you set your core and maintain an erect torso as you lower your body as deep as possible into the squat, while keeping your front heel firmly on the floor throughout the movement. As you begin to rise upward, exhale as you pass the halfway point during the ascent. Complete all the reps with one leg, then switch to the other to complete the same number of reps on the other side.
This is simply a stationary lunge (legs hip width, one leg in front, one in back) done with the back leg in an elevated position, usually on a step or bench. These are an advanced move (requiring strength and balance), I have done them myself, and do them with a few of my more advanced clients. You get a good hip flexor stretch in the back leg, while working the front leg.
I agree with Janet, and in addition it provides some additional core stability and balance work. It’s really important with this exercise to emphasis to your client to concentrate on ‘sinking at the hips’ rather than allowing themselves to move ‘forward’ when lowering their body.
Primarily the Split Squat works the quadriceps but it also targets the calves, glutes and hamstrings. What a lot of people may not know is that in addition to strengthening the leg muscles, split squats improve flexibility in your hip flexors, and if someone happens to have a bilateral leg imbalance, (that is a strength differential between the right and left legs), the split squat is one of many ways to go about correcting this. I personally had a hip tumor when I was younger and many surgeries and it left me with about 1/2″ difference in my legs and by doing this exercise, has made a big difference in both my balance and my strength of both my legs.
If you are working “legs”, it is a great exercise to fit into your workouts.