You could make a case that this is the single-worst piece of golf-swing advice

There's a lot of cliche' advice in golf instruction: "Hold the club like it's a baby bird." "Finish in a trophy pose." "Keep the left arm straight." In most cases, the advice was borne out of necessity, to get someone to make drastic changes to his or her golf swing when nothing else would work. That's certainly where "keep your head down" came from. Too many golfers rise out of their golf posture letting their head lift up in an effort to help the ball in the air, or they're so anxious to see the result of their shot that they take look up too soon.

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Unfortunately, "keep your head down" is an awful piece of advice, both for your golf game and your health. Dan Shipman, named one of Golf Digest's 50 Best Trainer in America, explains the health part.

"Neck issues are a big problem for many of my golfers," says Shipman, who trains players at his gym, Full Torque Fitness (@fulltorquefitness on Instagram), in Largo, Fla. "Whether it's an executive who lives behind a desk or a retiree who sits a lot, many struggle with mobility around the neck."

From a biomechanics standpoint, your neck is really good at doing one thing at a time, Shipman says. It can flex or extend (think up and down movement), it can side bend left and right and it can rotate left or right. When there is a general lack of mobility around the top of your spine, the cervical spine, you're putting extra stress on the entire neck region and that can lead to injuries.

"And when neck rotation is limited, the body looks to make up for that lack of function by getting movement from another area," Shipman says. "Most of our exercises with clients who have limited neck mobility are to get the upper traps (trapezius/upper-back muscles) to stop dominating. We'll also look at the lower traps, mid back and sometimes the serratus anterior (thorax region)."

Trying to keep your head down also sucks for your golf game, says 50 Best Teacher Hank Haney. It actually restricts your chance of making a functional swing. "Too much focus on keeping your head down prevents you from turning through the right way," he says. "Your timing will be messed up, and you'll probably hit the shot fat. Let your eyes follow the clubhead as it hits the ball and moves into the follow-through. In other words, synchronize the swing of the club with the turn of your head toward the target. You'll start hitting it more solidly and consistently."

At the the top of the page, Haney demonstrated what keeping your head down looks like at the top of the swing. This is what he'd rather see (below).

If you play a lot of golf, it's probably a smart idea to incorporate some neck and upper-body exercises into your fitness routine, Shipman says. Here he offers a few ways to improve this region of the body.