Your abdominal oblique muscles, on the sides of your belly, have an important function in the golf swing. They help you maintain your address posture as your trunk rotates, which is critical for making good contact. If you tend to slice the ball or hit it fat or thin, it's likely you're not staying in your address posture as you turn through the ball. In most cases, the body straightens, the shoulder plane flattens and the ball is struck with a glancing blow.
"If one of your buddies says you're standing up when you swing through, it's probably because the obliques aren't functioning as well as they should," says Golf Digest fitness advisor Ben Shear ([@benshear](https://twitter.com/benshear)). To find out if your core muscles are cheating you of yards, Shear says take this test:
1. Sit up in a chair holding a rolled-up towel or similar object between your knees (pictured above), with your hands gently touching the back of your head, elbows flared.
3. Once fully rotated, bend as much as possible toward your opposite knee and then as far as you can away from it.
Make sure you do this test rotating in both directions, and bend toward the knee and away from it, Shear says. If you can't bend without losing your maximum rotated position, or your elbows move closer together, or your torso drifts forward or backward, then your obliques need some work. Many times, Shear says, a golfer can perform the test in one direction, but not the other. This indicates a muscular imbalance between the left and right obliques.
The good news: The prescription to correct the issue is the same as the test, Shear says. Keep doing this twist-and-tilt exercise. The only adjustment is to gently push your body a little farther each time, holding the increased range of motion for five seconds before relaxing.
Ron Kaspriske is the fitness editor of Golf Digest.
(Photos by Dom Furore)