The barbell squat with plate slide is an exercise targeting the quadriceps, with the plate slide also working the adductors and abductors. It can help you get more total-leg and hip development out of squats, but is probably not the sort of thing you want to do with a seriously heavy load on your back.
To begin, first set the bar on a rack to just below shoulder level. Position a weight plate on the ground a couple feet back from the rack. Once the bar is loaded, step under it and place the back of your shoulders across it.
Hold on to the bar with both hands and lift it off the rack by first pushing with your legs and at the same time straighten your torso.
Step away from the rack and adopt a wide stance with the toes slightly pointed out, with one foot on the weight plate. Keep your head up at all times. This will be your starting position.
Begin to slowly lower the bar by bending the knees and hips. Continue down until the angle between the upper leg and the calves becomes slightly less than 90-degrees.
Raise the bar as you exhale by pushing the floor with the heels of your feet as you extend the hips and knees.
At the top of the movement, side step, bringing your feet together on the opposite side of the plate.
Using your inside foot, push the weight plate, sliding it across the floor to where you were just standing.
Place your inside foot on the weight plate, adopting a wide stance for the next repetition.