The Squat to Stand with Overhead Reach is my favorite mobility exercise, one that I do every time before I Squat, Deadlift and even Bench. There are 2 things you'll achieve by including Squat to Stands in your warm-up routine:
- One, you will boost your hip mobility (stretches hamstrings & adductors) so you can Squat deeper. This can eliminate nagging knee/back pain.
- Two, you'll increase your thoracic mobility (upper-back/chest). This helps achieving the low bar Squat position while improving your posture.
Watch the video of the Squat to Stand with Overhead Reach below. The guy in this video is Tony Gentilcore CSCS who Deadlifts over 550lbs. 
3 Squat to Stands Technique Tips. Do 2 sets of 8 reps as part of your warm-up. I also do reps between my Squat sets afterwards. You can never do too much mobility work, you will only gain flexibility and perform better on your Squat.
- Force Your Knees Out. Your stance should be wider than shoulder-width. Grab your toes and Squat down while pushing your knees out. Push your elbows gently against your knees to increase the stretch.
- Keep Your Chest Up. Same technique as for Squats: you do NOT let your chest sack in. Instead, you keep your chest up and your head inline with your spine (not looking at your feet or at the ceiling).
- Hold At The Top. Tony isn't doing this in the video, but when you reach overhead you should hold the position for 1 second before coming back down. Don't force the stretch, but don't rush it either.
You can find more exercises to boost your flexibility and eliminate nagging Squat pains once and for all inside Eric Cressey's new Show & Go system. Eric is a bestselling author with a 650lb Deadlift and a Master's Degree in Kinesiology so he knows what he's talking about. Click here for more info.