Beware this killer 'jackknife' golf swing mistake that can give you the shanks

The problem with coming over the top is that for so many golfers, it feels so natural. When the ball's down below you, it makes sense in theory to send the club towards it on the most direct route — as if you were swinging an axe — especially when your eyes are tricked into thinking you're aiming more to the right than you actually are.

It's why so many golfers, at some point during their golfing life, end up working on shallowing the club. They're trying to swing more from in-to-out, and hit less spinny slices as a result.

But what's the best way to do that? There are lots of feelings floating around, and the team over at Athletic Motion Golf, co-founded by Golf Digest Top 50 Teacher Shaun Webb and Golf Digest Best in State Teacher Mike Granato, break a few of them down in a fascinating and nerdy video, which you can watch for yourself below.

What is the 'jackkife' mistake?

Granato, speaking in the video, explains that one big mistake he often sees his them "jackknifing" the club at the top of the backswing. This happens, he explains, when golfers try so hard to excessively externally rotate their trail shoulder in the downswing that it pitches the club flatter, so much so that it ends up kicking the grip of their club closer to the golf ball.

Look at the photos below, and you'll see what he means.

When Granato draws a line directly up from the golf ball, you can see how the grip of the amateur golfer's club (the one with the red line) tracks more towards the ball line on the downswing than the pro's club. This often happens, he says, when golfers try to overdo a feeling they may have, and excessively externally rotate their trail shoulder during the first part of the downswing.

"Those movements jacknife the club down," he says. "When you add in the body turn, you get everything working out too far towards the ball. Moving the hands too far out, too soon, loads a shank into the system."

Nobody likes the sound of that. So what's a feeling Granato prefers? He suggests a quick mobility test, and says golfers should prefer the feeling of their arms lowering to start the downswing, rather than moving outward.

"It's like everything else in the downswing," he says, "you're just reversing what you did on the backswing."