Position the barbell across your traps, step back and have feet shoulder width.
Bend your knees to approximately 90 degrees.
Extend back up to the start position and repeat.
Knees caving in past big toes.
Using momentum to drop down.
Bending the back.
With the barbell racked at approximately armpit height, position your traps securely against it. Then press up and take a couple of steps back, positioning your feet roughly shoulder width apart and pointing slightly outwards.
Start by bending your knees until they are roughly at a 90 degree angle then push through the heels and squeeze your glutes to extend back up to the starting position. Engage your core to keep your back straight whilst pushing the hips slightly back on the way down and then thrust them forward on the way back up. Your knees should bend in line with the angle of your feet. Repeat for the desired amount of repetitions.
Perform the movement at a controlled pace and avoid having your knees cave inwards past your big toes when at the bottom of the movement.
