Stand in front of a barbell with your feet shoulder-width apart and pointing slightly out to the sides.
Bend down and grasp the barbell from behind using a pronated (overhand) grip.
Keeping your back straight and your chest up, stand up and lift the barbell up the backs of your legs.
Execution
Inhale as you flex your knees and hips and lower the barbell either to the floor or at least until your thighs are horizontal.
Exhale as you stand back up and lift the barbell up along the backs of your legs, driving through your heels.
Repeat.
Comments and tips
Keep your back and arms straight and your chest up.
To improve mechanical leverage, keep the barbell close to your body.
Keep your feet flat, and your feet and knees pointing slightly out to the sides, in the same direction.
Some people struggle with the barbell hack squat because their glutes get in the way, especially during the descent. If this happens to you, allow your knees to flex forward as you descend.
The barbell hack squat is great for developing your quadriceps. Compared with the barbell deadlift and barbell squat, it places less stress on your lower back, which makes it more suitable for those who suffer from lower back pain.
With the barbell hack squat, your hamstrings and gastrocnemii only act as dynamic stabilizers, which is why they have not been highlighted. I only highlight the target and synergistic muscles.