As a coach, not a day passes without someone saying to me, “I need a stronger core.”
Nobody will argue that a strong core is bad for you. But I think what most of us mean to say is that the stability that comes along with core strength can prevent and even heal some back injuries, while building a foundation for overall athleticism.

Core Mobility Comes From the Hips

Breaking Muscle Shop
Stability requires mobility to be useful, and for the core, mobility comes from the hips and upper thoracic spine. This is especially true now that many athletes have expanded their fitness paradigms to include gymnastics, hand balancing, crawling, and natural movement. If you want to crawl, practice MMA, or do yoga, you need good movement through your thoracic spine and hips. If you are locked up in these areas, your access to those movements will be limited. 
I’ve discussed twice before (here and here) how to open the upper spine. Now I will provide ways for you to open your hips and quadriceps. Most people are tight in these areas because they sit too much, which shortens the muscles that actuate the hip. If you’re not sure if you’re tight in your hips, try doing the Thomas test. Or you can try this simple test to see if your quads are the culprit.
a strong and mobile core
For your core to be athletically useful, it can't just be strong and stable. It must also be mobile.

Immobile Hips Are Ruining Your Squats

Shortened hip flexors place your hips into constant flexion, and drag the upper spine along with them. This forces you to shift your weight back and your posture forward, which decreases length in the hip flexors and quads even more.
Squatting in this posture is a complete trainwreck. Most of the time, you will push your knees forward, driving the force of the load into the knee joint and quads, with little or no help from the hamstrings and glutes. Your quads end up doing most of the work, and you put your knee at risk for injury.
The only way to keep your knees back with this posture would be to compensate by dropping the chest forward without moving the hips back. This increases the pressure on the low lumbar spine and decreases the activation of the glutes and hamstrings. With all of the weight going into the lumbar spine and no help from the hamstrings, glutes, or quads, you've got a perfect recipe for a serious back injury.  

3 Stretches to Open Your Hips and Quads

In this video I will give you three ways to stretch your hips and quads: 
  1. A basic lunge that you can modify with blocks on either side of the body as a starting point. 
  2. An intense partner stretch I learned from Stretch Therapy™. If this stretch is too challenging, back up and start with the first lunge sequence with blocks. Stay with this stretch until you feel more comfortable and can go deeper. You can also add this gentle quad stretch to further your progress.
  3. If these are both too difficult, try doing the last one.



Want Deep Squats? Spend Time Getting Mobile

Take your time with these stretches. The quads are large muscles, and it will take a few weeks for some of you to see the difference. Getting deeper in your squat requires an open thoracic spine, mobile hips, and length in the quadriceps. Perform the drills from each of the three videos in this series every day to increase your flexibility, and you will feel the difference.
More Mobility to Enhance Your Strength:
Photo courtesy of CrossFit.