For functional leg strength, you'd be hard pressed to find a better exercise than the not-so-common box squat. Think of it as the lost twin of the traditional back squat — similar looking, yet rarely seen. The box squat eliminates the bounce-at-the-bottom effect that often happens during a classic back squat. Without the bounce, you're forced to fire more muscles to raise back up. This makes it a great tool for building your glutes, quads, and hamstrings, along with your mid and upper back.
Start with a box height that allows you to squat so your thigh is no more than three inches above or below parallel to the floor. (Easy tip: Choose a box as tall as your leg from ankle to knee). If your box is too short, add a few weight plates or rubber mats on top. If your gym doesn't have boxes, straddle a bench.
On leg day, replace a non-functional machine exercise, like seated knee extensions, with four sets of five reps of box squats (see a video demo here). The first two sets are your warm-up, so go easy. For the final two sets, choose a weight that's challenging but allows you to perform the exercise with perfect form. And keep these five tips in mind:
#1: Get Mad at the Bar
A quality box squat starts with a focused set-up. Grab the bar and squeeze tight, like it just insulted you. Use a shoulder-width grip. Duck under and pull your shoulders back so the bar sits on the natural shelf created by your shoulder blades.
#2: Tear the Bar Apart
Pull your elbows forward, take a deep belly breath, and tighten your midsection, like you're preparing for a gut punch. Imagine the bar is a towel and you're pulling it taut, bringing your shoulder blades down and back. This creates tension in your lats, which is transferred to muscles that protect the spine.
Maintain this tightness in your upper body and unrack the bar. To conserve energy, take only two steps back. Make sure one corner of the box is angled forward so you can straddle that corner. Set your feet wider than shoulder width and turn your toes out slightly.
#3: Thrust Hips Back
Keeping core tight, back flat, and chest up, reach your hips back while driving knees out. Think of someone standing behind you, pulling you by a rope that's tied around your waist. When you can't shove your hips back any farther, push a little more. Sitting way back on the box allows you to keep shins perpendicular to the floor, which helps reduce knee pain.
#4: Sit on "Broken Glass"
Slowly lower to the box without rounding your upper back or losing belly tension. Don't plop down. This places excessive pressure on the lower spine. Instead, imagine you're sitting on broken glass — you should only pause on the box for a second or two. This pause allows elastic energy, built up in your muscles and soft tissues, to dissipate as you change directions from squatting to standing. You'll reduce injury risk while boosting the effectiveness of the exercise.
#5: Blast Off the Box
Drive through heels, push knees out, and explode through hips to stand. To build better strength, resist the urge to rock off the box.