A while back, after doing an exhaustive study of how elite players strike a ball on the turf, former pro golfer Bobby Clampett, now an instructor, found that the swing bottom of the best players is up to four inches in front of the ball!

You read that right. Four inches. Their irons descend into the ball, strike it, then slice into the turf and keep heading downward for another couple of inches before ascending again. That’s why you see those carpet strips of grass flying when someone like Tiger pures an iron shot.

You might wonder what they’re doing to create such a powerful impact condition? In short, it occurs because their hands and lower are in front of the ball as the clubhead strikes it. Hard to picture? Here’s a look at defending U.S. Open champion Wyndham Clark a millisecond before impact (below). Note his belt buckle and hands. See where they are in relation to the ball?

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You might think Clark can hit a 7-iron 200 yards because he’s been playing and practicing golf his whole life, and you wouldn’t be wrong. But there’s another reason why he’s able to deloft his irons and compress the ball off the turf, and it doesn’t have to do with outlier golf skill.

It’s a gym thing.

Darin Hovis, a Golf Digest Certified Fitness Trainer, says that “lagging” action, where the clubhead trails the hands and body rotation through the impact zone, can be trained in the gym. It takes a combination of strength, stability and mobility, plus the coordination of moving in multiple planes in a timed action, but it’s easier than you think if you follow his four-part workout.

Hovis, one of Golf Digest’s 50 Best Fitness Trainers in America, trains golfers at Par 4 Fitness in Naples, Fla. and is a +0.1 handicap golfer (so he pure irons as a hobby). He says the key to turning a 7-iron into a 5-iron, by making ball-first contact and taking a divot after, lies in understanding how to use the ground as a leverage post.

“You want to train to learn how to deliver the hands forward of the ball enough to create this dynamic compression,” he says. “A lot of the time amateur golfers throw the clubhead at the ball and it’s actually ahead of the hands at impact. It’s not lagging the way it does when pros strike the ball.”

Watch his four-part training program on how to train for clubhead lag. And click this link if you’re interested in knowing more about Golf Digest’s Fitness Trainer Certification program.

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This article was originally published on golfdigest.com