Golf release: the rate the clubface turns

Release is a rate, and the unit is degrees per second

1,800–3,600 °/sPeak clubface rate of closure, golfers of any standard

Foresight Sports puts a number on it. On their launch monitors, closure rate is the rotation of the clubhead heel to toe about the shaft, in degrees per second or rpm. That is release as a measurement rather than a feeling: the face sits open to the target line, arrives roughly square at the ball, and that changeover has a speed.

Sasho MacKenzie, whose primer on the subject sits on Golf.com, writes that rate of closure peaks near impact, and that a typical range for any group of golfers, whatever their standard, runs from 1,800 to 3,600 degrees per second. With 0.04 seconds left before contact, tour players included, golfers still have 70 to 100 degrees of face closing to do. Nobody steers a rotation already running that fast.

The 94-golfer spread, and what it did not predict

652 to 2,432 °/sHandle twist velocity at impact, 94 tour professionals

Phil Cheetham's 2014 doctoral dissertation captured 94 tour professionals on the AMM3D system, a sensor clamped to the shaft below the grip sampling at 240 Hz. It reported handle twist velocity at impact: the speed the grip turns about its own long axis. The mean was 1,307 degrees per second. The slowest professional came in at 652, the fastest at 2,432.

Against clubhead speed that number correlated at r = .14, and against driving accuracy at r = -.14. Set the fastest 32 golfers beside the slowest 32 and clubhead speed came out at 109 miles per hour against 107, not significant. Accuracy, 62.2 per cent against 63.9, also not significant. Twenty-three in each group of 32 had won on the PGA Tour.

Posture is what did separate them. At impact the slow-twist players were further open, 31 degrees of thorax rotation against 23, and further side bent away from the target, 34 against 28. A release speed comes attached to the body that has to accommodate it.

Forearm roll is part of it, geometry is the rest

Lead forearm supination is the part most people mean by release. Cheetham measured a mean of 1,569 degrees per second at impact, individuals from 851 to 2,299, tracking the handle at r = .68. His fast-twist group supinated at 1,811 against the slow group's 1,295. He cites MacKenzie and Sprigings's model, which makes axial rotation of the lead arm and forearm the primary mechanism squaring the face.

Geometry supplies the rest, which is where the shorthand about rolling your hands over goes wrong. MacKenzie counts three contributors. Swinging faster closes the face faster. The inclined plane closes it for nothing: at 90 mph of driver speed, a plane 30 degrees from vertical adds roughly 800 degrees per second, a flatter one at 45 degrees roughly 1,200. Only the third, shaft twist, is forearm rotation.

The lead wrist barely features. Its extension velocity at impact averaged 433 and 446 degrees per second in Cheetham's two groups, under a third of the forearm figure and indistinguishable between them. Release is not mainly the wrist letting go.

Roll, block and the names that do not line up

PGA professional Jack Backhouse, writing for National Club Golfer, splits release into three. In a roll release the trail hand rolls over the lead hand until the forearms touch. In a block release the trail arm and wrist stay bent well past impact and the face feels square or open; he names Viktor Hovland. His third, the Hogan release, extends the lead wrist while the trail wrist bends under, adding loft without closing the face.

That vocabulary is older than the video. Cheetham traces the same split to Cochran and Stobbs in 1968, who sorted players into Rollers, Squares and Pushers by how far they twisted the shaft going back, more than 90 degrees, exactly 90, or less; and to Suttie in 2011, who called the two ends open-face and closed-face. No gap appears in Cheetham's scatter where a category should stop.

Reading the frames after the ball has gone

About 44°Grip rotation between two frames of 30 fps video, tour mean

Arithmetic first. At Cheetham's tour mean of 1,307 degrees per second, the grip turns about 44 degrees around its own axis in the 33 milliseconds between two frames of 30 fps video. MacKenzie's closing window, 70 to 100 degrees inside the last 0.04 seconds, is roughly one frame and a bit long. Your phone will rarely hand you the frame of contact.

So the follow-through earns a look. The rate peaks near impact rather than ending there, which makes the first clean frame after the ball has gone a sample of the same rotation, slow enough to resolve. Backhouse's markers show up there: forearms crossed and touching is a roll; the trail wrist still bent, arms running out toward the target, is a block.

None of that gives you a number. Foresight's camera units report closure rate as a club delivery figure; TrackMan's published club data list, club speed, attack angle, club path, face angle and dynamic loft, carries no rotation rate. Pebble Swing reads joint angles and the backswing-to-downswing tempo ratio out of the frames, and a rate about the shaft is not among them.