Placing the barbell in the crook of your arms for a squat fires up your abs and helps take the load off your spine. It's also a good front squat alternative if you don't have the hip and shoulder mobility for that move. Be warned: It might be one of the toughest exercises you’ll try. Because there's no longer a vertical load on the back, the low back and ab muscles have to work a lot harder. Feel free to wrap the bar in a towel or pad where it sits in your arms. The weight can get uncomfortable as it gets heavier.