Looking for a little more oomph in your downswing? Train this muscle

Every golfer in the pro ranks has some aspect of his or her swing that stands out. For big Sepp Straka (above), who has three wins on the PGA Tour, it's the power he generates swinging down. Sure, he's listed as 6-foot-3, 235 pounds in the PGA Tour media guide (and probably bigger in real life), so you could argue his massive body is the reason his swing looks so powerful. However, one key reason he can pulverize a golf ball is the strength of his shoulders, says John Tillery, one of Golf Digest's Best Teachers in Georgia.

Straka's arms are huge, but other fast swingers in pro golf don't have nearly as much muscle mass. So how are they able to get from the top down so quickly? The key might be the functionality of the subscapularis muscles, says Dee Tidwell, a Golf Digest Certified Fitness Trainer and one of the 50 Best in America. Tidwell trains golfers at Colorado Golf Fitness at the Studio in Denver.

"The subscapularis muscle is the largest of the four rotator-cuff musculature, and one of the most important for golf because it’s the only internal rotator (rotates the arm inward) of the group," Tidwell says. "It also is important for adduction of the arm, which is when the arm moves toward the body. Both movements are crucial to a golfer from transition to impact, because the arm is going from almost maximum external rotation with a bent elbow and abduction to straightening the elbow, internally rotating and adducting the arm.

"Since it is a stabilizer of the gleno-humeral (shoulder) joint, it can present problems for the other three rotator-cuff muscles if it's weak."

EMG testing shows the subscaps are extremely active in the forward swing, especially the muscle in the dominant arm, and they provide an extra boost to speed generated by body rotation. They also stabilize the golf swing down and through impact and help slow the club down afterward. Not to sound gory, but they help keep your arms from flying off your body.

Training them is simple, Tidwell says. And he will demonstrate what you should be doing to keep them functional and strong.

"The following exercises not only create better movement capability for the subscap, they also help all the rotator-cuff muscles remain in balance working synergistically to create stability and mobility in the shoulder and arm," he says.

Follow along with Tidwell here:

Scapulo normalizations

Lie prone with one arm behind your back and the other above your head so both elbows are about 90 degrees. Try to align your hands with your spine. Look toward the down arm. Lift the elbow of your lower arm five times, then lift your upper elbow five times; then lift both at the same time for 15 reps. Switch sides and do 2-3 sets of above of each arm in each position.

Subscapularis myofascial stretches

Lay prone on a table and place one arm flat with a 90-degree angle at the elbow. Place the other arm in a pushup-like position and turn your head toward that side. Keep your ear on the table, then push into the table with the push-up arm. That will make your torso move upward like the arrow shows. That will also push the other arm down. Now actively push that same shoulder into the table while simultaneously reaching that elbow away from the body. Do 2-3 sets of 30-second active holds (meaning, keep doing the described above for 30 seconds).

Prone internal/external rotations for subscapularis and teres minor

Lay on a bench or table and place a small towel under your arm. From the neutral position, externally rotate your arm while keeping your upper arm connected to the towel. Rotate as far as you can, then internally rotate your arm with the same rules. Do 2-3 sets of 20 reps each way.

Standing arm external rotations with a resistance band

Anchor a lighter-tension band and extend it with one hand. Turn your body toward the band about 15 degrees, then allow the band to pull your hand back into external roation, making sure to control the speed and not allow it to go farther than comfortable. Next, internally rotate your arm so your hand moves toward the parallel position. Do 2-3 sets of 20 reps with each arm.

Single arm protractions and retractions

Place a hand on the wall either vertically or internally rotated (fingers point inward) and allow your chest/ribcage to sink toward the wall. Done correctly, you’ll feel your scapula (shoulder blades) migrate backward toward your spine. Pause and now do the opposite, pushing your arm into the wall and your chest/ribcage away from it so your scapula migrates forward with the arm. Do 2-3 sets of 20 reps with each arm.

Click on this link if you're interested in becoming a Golf Digest Certified Fitness Trainer.