When squatting, you often hear coaches cue "arch your back!" But how much arch is too much? For anyone with tight hip flexors, weak abdominal muscles, or a hyper-mobile spine, too much arching in the lower back creates a postural fault that I myself have to consistently work on - lower crossed.
Lower crossed (also called excessive lordosis) is generally regarded as a female postural fault, as it is emphasized with the posture created by high heels. However, this is a common problem for men and women alike, and can happen to anyone with tight hip flexors, i.e. someone who spends the majority of their day seated at a desk.
How it Affects your Game
So what? Well, I'll tell you. Ignoring this positioning will lead to many issues in your CrossFit performance. The power you can muster for your overhead movements, power clean and snatch will be reduced. As this posture compromises your mid-line stabilization, You will have to fight to get ideal set positions, and will limit you on your squats numbers. Additionally, you can develop chronic neck and back pain (and as the song goes, the back bone's connected to the hip bone... and so on and so forth).
If this is a postural position you tend to adopt, you need to address these issues on your own before class and at home. You will need to work both on mobilization of your hips and quads as well as strengthening your deep abdominals and glutes. For a solid article of how to go about this, I strongly recommend reading the CrossFit Journal article Tuning the CrossFit Athlete - Part 2. As Kelly Starrett, owner of San Francisco CrossFit and author of MobilityWod, Deskbound: Sitting is the New Smoking, and Supple Leopard says, "I come pre stretched." Handling your body's junk before you CrossFit will help you get after it and get out of it what you put in.
Got questions? Had issues with your lower back? Post to comments below.