Fronts Squats are NOT part of the StrongLifts 5x5 routine because you can lift more weight with Back Squats. This is important because heavier weights stress your body more and this means more muscle and strength gains.
Here's why you can Squat much heavier weights with the Back Squat: the front bar placement on Front Squats pulls you forward and forces you to keep your chest up in order not to lose the bar. So your legs won't be the limiting factor on the Front Squat, it will be your upper-back keeping your chest up.
Front Squats are therefore great to assist Back Squats, but not a replacement for Back Squats. From my experience, if you only Back Squat and increase your max, so will your Front Squat increase. But if you only Front Squat, you won't gain much strength on Front Squats and your Back Squat will hardly increase.
Here are some of my best tip to master the Front Squat technique...
Clean Grip vs. Crossed-Arm Grip. I do not recommend Front Squatting using the bodybulding-style crossed-arm grip. Here's why: it's much harder to keep your elbows up with the crossed-arm grip, and if your elbows don't stay up, the bar will roll off your shoulders. The clean grip is therefore not only safer than the crossed-arm grip, it also allows you to Front Squat heavier weights.
The Front Squat Setup. Like with Back Squats, your body is supposed to hold the bar not your hands. On Front Squats this means you should keep your chest up at all times so your shoulders support the barbell, not your wrists. If you try to support the weight with your hands, it will hurt. Chest up, elbows high, open hands. Don't hesistate stretching your wrists and triceps if you lack flexibility.
- Foot Stance. Stance should be slightly wider than on the low bar Back Squat. Start with shoulder-with stance, go a bit wider.
- Toes Out. How much depends on your foot stance, but they should always point in the same direction as your knees. So 30-45° out.
- Chest Up. Put your chest forward and lift it up. This gives the bar a solid base to sit on & makes it impossible to round your upper-back.
- Tighten Lats. You can't tighten your upper-back on Front Squats like on Squats. However you can tighten your lats: spread them.
- Look Forward. Up is bad for your neck, down will make your lower back round. Look forward, fix a point in front of you.
- Bar Position. Behind your clavicles and close to your throat. Coughing is possible and clavicles may hurt. Front Squat more, you'll adapt.
- Hands Open. Your shoulders support the weight, not your hands. Open your hands, relax them. Three fingers under the bar is okay.
- Elbows Up. Put your elbows up with your upper-arms almost parallel to the floor so the weight doesn't end up hurting your wrists.
- Elbow In. Push your elbows toward each other during the Front Squat. This will be easier on your wrists.
How to Front Squat. Sitting back is harder on Front Squats because of the front bar placement and upright position - if you sit back too much, you will lean forward and lose the bar. However, you should try to Front Squat "between your legs" like Coach Dan John said. This involves your hip muscles more.
- Sit Back. Squat between your legs while pushing your hips back. You'll stretch your hip muscles when breaking parallel. Bounce from it.
- Break Parallel. Should be easy because of the upright position. Squat down until your hip joint is at least lower than your knee joint.
- Knees Out. Squat up and down while pushing your knees out. Do not allow your knees to buckle in, it's guaranteed to cause knee injuries.
The best way to increase your Front Squat is to increase your Back Squat. Check out my article on Back Squat technique.