The golf grip, in degrees of clubface angle

Three grips, one clubface, five degrees

About 5 degreesClubface angle at impact, strong grip against weak, twelve PGA professionals

Howie Carson, Jim Richards and Bruno Mazuquin sat twelve right-handed PGA professionals in front of ten motion-capture cameras and had each hit eight drivers with a strong grip, eight with a neutral one and eight with a weak one. Strong meant the lead hand on top of the handle showing three knuckles, the trail hand underneath showing one. Weak was that reversed. Neutral showed two knuckles on each hand.

Mean clubface angle at impact came out 1.5 degrees open with the strong grip, 2.6 degrees open with the neutral one and 6.4 degrees open with the weak one, measured against the ball-to-target line. Only the weak grip separated from the other two by a significant margin, at P = 0.011 against strong and P = 0.019 against neutral. Strong against neutral did not separate at all. Note the conditions: a squash ball hit at a laboratory wall fifteen metres away, with face angle read from markers on the clubhead rather than from a ball in flight.

The V's, and why the weak grip is the outlier

15 degreesSpacing between the five grip positions tested on TrackMan

In a neutral grip the V between thumb and forefinger of each hand points at your trail shoulder, which is the checkpoint Foresight Sports uses. Turn both hands clockwise from there and more lead-hand knuckles come into view; turn them the other way and fewer do. That rotation is the entire strong-to-weak axis, and it is the only part of the grip with degrees attached to it. The slice guide covers the repair at one end of that axis, where a face leaking open gets rotated back.

Morgan D'Arcy and colleagues measured the axis on a TrackMan radar. Twenty-eight recreational golfers, mean handicap 15, driver speeds between 120 and 153 km/h, hit from five grip positions spaced fifteen degrees apart across a sixty-degree range. Grip position significantly affected six accuracy measures, clubface angle and club path among them, and two distance ones. Neutral and the stronger positions gave the best accuracy and the best distance, while the weaker positions were significantly worse at both. A symmetrical change produced asymmetrical results, which is what the laboratory means hinted at.

Overlap, interlock, all ten fingers

How the hands join each other is a separate question from where they sit. The overlapping grip rests the trail little finger on top of the lead hand, the interlocking grip hooks it between the lead index and middle fingers, and the ten-finger grip joins nothing at all. Foresight Sports pairs the overlap with larger hands and names Phil Mickelson and Adam Scott, the interlock with smaller hands and names Tiger Woods, Jack Nicklaus and Rory McIlroy, and the ten-finger grip with juniors, beginners and players who arrived from baseball.

Neither study above touched the connection. Both changed rotation and held the rest still. No controlled comparison of the three connections for clubface angle, clubhead speed or accuracy appears in the literature, so the confident claims that one of them adds speed are long-serving opinions rather than findings. Rotation has numbers behind it. The link between the hands does not.

Pressure is a curve, not a setting

Under 7%Swing-to-swing spread in one golfer's grip force, eight low handicappers

Steven Langlais and John Broker instrumented the handles of eight low-handicap golfers' own 7-irons and drivers, USGA indexes of zero to seven, and recorded what the hands did through the swing. Force fluctuated widely rather than holding a level. The dominant forces came from the lead hand, and within it from the last three fingers. Each golfer repeated their own pattern closely, with standard deviations under seven per cent of total force, and their 7-iron and driver traces correlated at r-squared 0.86.

Coach Michael Jacobs makes the same point without a sensor: pressure changes during the swing whether you intend it or not, the way your hand adjusts on a fork. The two hands are also not doing the same job. Hyeob Choi and Sukyung Park built a six-axis force-torque sensor into a driver grip and measured nine right-handed professionals directly, finding roughly three times more torque from the trail hand than from the lead one. The lead hand holds and the trail hand turns.

Where the averages stop being useful

The spread inside those laboratory numbers is wider than the effect. Clubface angle at impact carried a standard deviation of 4.7 degrees under the strong grip and 6.9 under the weak one, both larger than the 4.9-degree gap between the two group means. Carson's group then read the individual files and reported that not one participant matched the tidy strong-neutral-weak ordering the averages showed. The direction of the effect holds. Its size, for any one golfer, is a guess.

Clubhead velocity did not move: 38.2, 38.6 and 38.0 metres per second across the three conditions, with no significant effect of grip type. And the grip you set is not the grip you deliver. Lead-wrist extension differed by about eleven degrees between the strong and weak conditions at address, and by about six by the time the club reached the ball. Pebble Swing reads joint angles and the backswing-to-downswing tempo ratio out of the frames, but your hands on the handle are the one thing a single still at address already shows.