Do the Zercher Squat
It hits the whole lower body just as well as a back squat or front squat. And it's amazing for the traps, upper back, and biceps. You need these muscles to hold the bar properly. It's also one of the best exercises to build a solid core.
"Zercher" just means that the bar is held in the crooks of the elbows and the arms are flexed to prevent it from dropping. So you can do Zercher squats, Zercher deadlifts, and even Zercher carries. And with the squat version, you can do anything with it that you do with a normal squat: 1 RMs, accommodating resistance (chains and bands), etc.
There are two main ways to hold any Zercher lift: connected and unconnected.
1 – The Connected Variation
Both hands are joined together, grabbing each other.
Since we still want to maintain an elbow width that's about shoulder width, the shoulders will be internally rotated to allow the hands to connect. This variation is considered stronger because it makes it easier to hold the bar solidly close to you and prevent the arms from opening up.
The upside is that if your arms or upper body are holding you back in regard to how much weight you can lift, it'll allow you to use more weight than with the unconnected version. I sometimes use the connected grip when going for a personal best and I feel the bar slipping.
The downside is the internally-rotated position at the shoulder, as well as the reduced load on the biceps. So it might make it less effective to build your upper body as well as put more stress on the shoulder joint. The connected variation also favors rounding up the upper back when squatting, which we don't want.
2 – The Unconnected Variation
The hands are apart and the forearms are ideally perpendicular to the ceiling which puts your shoulders in a neutral position.
The unconnected grip increases loading of the upper back and arms. The downside is that you might have to use less weight if your upper body is too weak to hold the load properly. In most cases I recommend the unconnected grip since it makes the movement a bit more complete.
What I like with the Zercher squat is that it helps long-limbed lifters to shift a lot of the load on the quads. The grip forces you to stay fairly upright and the position of the load (more forward) also seems to help keep an optimal position, much like in a front squat or goblet squat.
Use the same squatting style you normally use. If you squat with a wider stance, do the same thing with Zerchers. If you prefer a narrower stance, use it on the Zercher too. Some people break at the hips firsts, others at the knees. I recommend using the approach that you're more comfortable with.
Once you become comfortable with the Zercher position, you should be able to Zercher squat around the same weight as you front squat. It could be a bit more or less depending on upper body and core strength.