Muscular symmetry is paramount to staying injury free, and you should always exercise muscles on the left and right sides of the body—as well as the back and front—similarly. However, when it comes to synchronizing the downswing and creating clubhead speed, a key ingredient is generating good internal hip rotation on your dominant side (right hip for right-handed swingers). What does having good internal hip rotation mean? If you're sitting as you read this, with your butt on the edge of the chair and feet on the floor about shoulder-width apart, you should be able to touch your left knee to your right and vice versa—or at least come very close—without having to move the other leg inward.
Watch the video below to see Andrew and one of his students demonstrate it.
And if you're interested in more ways to improve your swing using flex bands, their SuperFlex Golf Swing Kit ($69.95) comes with a variety of bands and how-to instructions. You can buy it at superflexfitness.com. A single band costs $5 to $36 depending on thickness and function.
Ron Kaspriske is the fitness editor of Golf Digest.