Add 42 yards now!

As Rick Smith demonstrates above, many golfers start down with the upper body, which pushes the club to the outside (left). To stay inside, let the legs and hips lead the downswing (right). Smith shows how to swing from the inside on pages 96-101. Below, note the dramatic difference in yardage between a downswing that approaches from 9 degrees outside the target line and one that comes from inside or on the line.

Think about that for a minute: What would another 42 yards on your tee shot do for you, besides get you jazzed to play more golf? Maybe make some of those long par 4s reachable in two, or even the par 5s. You might be able to hit a short iron into more greens -- hey, we love those new hybrids, too, but who wants to pull them out on every hole? Fact is, distance makes golf a more enjoyable game. In this package, we share our findings from an exclusive Golf Digest test in which we measured the effect of swing path on driving distance. It's commonly said that power comes from hitting from the inside, but here we quantify what that really means. Then Golf Digest Teaching Professional Rick Smith goes through the faults that prevent the inside approach and offers tips and drills for achieving it. Finally, we share the power secrets of eight tour players. You might never hit it like them, but 42 more yards is a darn good start.

The idea is not new.

Horace Hutchinson, whose book Hints on Golf basically invented the art form of written golf instruction, suggested it in the 1880s. The great British champion J.H. Taylor discussed it about a hundred years ago in his own volume on instruction. And J. Douglas Edgar, winner of the French and Canadian Opens before the introduction of the steel shaft, actually created a training aid in 1920 to groove what he called "the movement," saying "it has the exhilarating effect of champagne, without the aftereffects."

It's what we call today "hitting it from the inside," otherwise known as swinging the club on a path that approaches the ball from the golfer's side of the target line as opposed to outside. And though it's a common refrain from instructors and a somewhat obvious swing theory (everybody knows that swinging out to in is a sure way to hit a weak slice), for the first time Golf Digest has documented the real value of the inside move. Just how important is it? In the bluntest of terms, it's 42 yards more important. Champagne effect, indeed.

Utilizing a robot simulation of the golf swing from industry testing leader Golf Laboratories Inc., we were able to mimic downswing paths at six angles, as well as a straight-on, or neutral, approach. At a swing speed of 95 miles per hour (slightly faster than average), our results show that an inside path of 3, 6 and even 9 degrees, as well as the neutral swing path, combined to produce drives averaging 244 yards. But when those paths veered outside the target line, bad things started to happen. The average on as little as a 3-degree out-to-in path was 233 yards, or a loss of 11 yards versus the neutral-inside paths. At 6 degrees the loss of yardage was a whopping 30 yards. At 9 degrees, average drives were going just 202 yards, for a loss of 42 yards, as in the numerals "4" and "2."

What was going on? Looking at the numbers on TrackMan's ball-flight radar system, it's fairly simple physics. Shots hit from the inside were mirroring the distance maxim of high launch/low spin. (Generally speaking, the higher you launch the ball with a lower amount of spin per degree of launch angle, the farther your drives will go.) In our test, the out-to-in swings were doing just the opposite: launching low with a lot more spin per degree of launch angle. The neutral and inside paths produced launches more than twice as high (13.6 degrees versus 6.2) with spin rates less than half those of the out-to-in swings (203 revolutions per minute versus 452 rpm per degree of launch).

Those severely out-to-in paths might seem outrageous, but sadly, they're not. According to Dave Anderson, TaylorMade's director of research, the universe of golfers they have tested on the company's swing-analysis system falls along a swing-path range that stretches to 11 degrees out to in. Meanwhile, the majority of tour players in TaylorMade's research stays within a range of neutral to about 3 degrees inside.

Fredrik Tuxen, the inventor of TrackMan, has studied swing path at the tour level. His research shows that a great influence on distance is the trajectory the clubhead takes into the ball. Specifically, players who hit down on the ball are not maximizing distance. (This is important to our research because generally speaking, an out-to-in swing produces a downward hit, and an in-to-out swing leads to an upward strike.) According to Tuxen, two players can have the same swing speed, but the player who attacks the ball on the upswing can produce as many as 28 more yards than a player with a downward strike. One solution can be found in equipment, he says.

"It's very difficult to change one's clubhead speed," Tuxen writes in a paper presented in March at the World Scientific Congress of Golf V in Phoenix. "Also, the attack angle is difficult for most golfers to change without intervention, such as instruction. So, the easiest thing the golfer can do is change the club!" (See box, below left.)

Still, to see the real benefits of the inside path, you need to make a swing change. "Biomechanically, great players look so good because they're so efficient at using their bodies," says Dave Phillips, co-founder of the Titleist Performance Institute. "How often do you hear, 'They swing so slow and hit it so far -- how do they do it?' The reason is, everything is moving in harmony." Harmony. Champagne. Either way, hitting it from the inside is pretty sweet.

The robot never lies

The Golf Laboratories swing robot simulated seven paths at a slightly above-average speed. Inside and neutral swings produced an average of a 42-yard gain over the most extreme outside path.

Can't fix swing? Change clubs

Don't have time to correct your out-to-in swing? Try a higher-lofted driver as a temporary solution. It will improve your launch angle and mitigate the effects of sidespin without a meaningful loss of ball speed.