Squat Wedge Block Set of 3/5 - 960 LBS Capacity - Slant Board for Calf Stretching with 5 Stackable Angles - Calf Stretcher Slant Board - Workout Equipment - EPP Material for Exercise Equipment & Physical Therapy

when I'm at the bottom position of a back squat for some reason I'm willing to bet you're butt-winking. Essentially you're going down farther than your ankle flexibility allows, which causes your hips to bend at the bottom of your squat. This causes your back to no longer be straight, and can cause lower back strains. Stand with a 2.5lb weight on your heels, or buy some wedges to raise your heel, which allows you to go down further without the butt-wink.