Art De Vany: Torque and Power in the Golf Swing

« What Hump? | Main | Followup to Torque and Power in the Golf Swing »

Torque and Power in the Golf Swing

June 16, 2005 04:13 PM

I love to do these analyses of the golf swing (and of the baseball swing too). It is preparation for my plan to play at bit more golf. I may do some long drive competitions too, but not with those 50 inch shafts (I think they just changed the rules to limit the shaft to 46 inches, so that a long drive is no longer a trick shot). I am mostly a FT person and a shorter shaft actually lets me generate more club head speed, but I am getting ahead of myself.

These are some reflections based on research in The Physics of Golf by T. Jorgensen and and article in Sports Engineering (2002) 5, 23-32 by E. Sprigings and S. Mackenzie. It is called Examining the delayed release in the golf swing, but it has a lot of other good information.

It had been thought that 3040 watts was necessary to hit long drives. This is about 4 horsepower to generate a club head speed of 100 mph. But, it turns out a lot less than 2040 watts is required; it is more like 1650 watts. And this is because linear reaction forces at the joint centers transfer energy to the club head by joint-force power.

Consider power generation at the shoulder, the wrist and the torso (this is shoulder rotation about the spine, with some hip rotation too). The powers generated at these points are: shoulder 800 W, wrist joint 600 W, torso 390 W. The shoulder joint transfer point generates the highest power, followed by the wrist joint. No wonder Annicka can hit 300 yard drives; she has the best wrist release in golf and her arm-torso separation is excellent. That is, her arms speed up relative to her torso as she almost "walks" through the swing. The slow tempo of her torso is a key; this segment only contributes 390 W, so keep it smooth and it serves as a point for absorbing the torque reactions from the arms and wrists. As the shoulder rotates, the torque reaction transfers to the torso and tends to slow it down. Walking through the rotation absorbs the torque reaction. As the wrists release, the arms slow down as they absorb the torque reactions.

The way the segments slow as the power is transferred to the next one down the chain from torso to shoulder to wrist to club makes a well-synchronized swing look slow. Even when the club head speed is 120 mph.

Annicka's wrist release (unhinging of the wrists, forearm rotation and extension of the bent right arm at impact) must be one of the best ever seen. Her release and shoulder-arm acceleration are more than 3/4 of her power and her smooth torso rotation absorbs these forces. Thus, she looks so smooth and yet generates high power. So does Ernie Els. Both of them look like they are swinging so slowly because their torso rotation is slow, but continuous and supporting to the higher power generated in their shoulder and wrists.

The torso is mostly slow twitch (ST) fiber. So, the torso generates high torque, but not such high power because of the slow movement of the uncoiling. The higher torque of 120 N m in the torso was exerted only at a rotational speed of only 3.25 radians per second, thus generating only 390 W.

The shoulders and wrists are predominately fast twitch (FT) muscle fiber. So, they generate high speed and power, even though they produce less torque than the torso.

So, don’t spin the hips as this cannot produce much power and causes all kinds of problems. Do release the wrists and begin far enough before contact. This also favorably affects club path, promoting a more in to out path and keeps the club head going down the line longer.

The delayed release adds a bit more power, about 5%. The downswing takes about 0.34 seconds with a delayed release and 0.36 seconds without it. The retention of wrist cock shortens the swing path and delays the negative torque reaction of the release on the arms, shoulders, and torso. So, the swing is faster.

The release has to be full and must be initiated at 0.10 seconds before impact. This is just after reaching the final third of the downswing.

The modern swing is described by many, including Gary White here at Coral Canyon, as a dropping of the hands, a release, and a "walking through" the swing. Not bad at all. This has about the right tempo in the parts to maximize power, using the torques and speeds of each body part. Dropping the hands on the right path promotes a build up of power in the wrist cock and a bit of a delayed release. Having the hands closer to the body increases the rotational speed of the arms relative to the rotating torso. The smooth flow of torque through the torso prevents "spinning out" and excess rotational speed and, thus, keeps the swing path on line. Tiger sometimes spins his torso, hips and shoulders so fast that his club face stays open and he may even change his spine angle or central point of swing rotation. I have fast legs and hips too and this has been one of my problems.

You can see now that this is dumb. Torso rotation is a minor source of power relative to the shoulder and wrists. Keep a smooth flow of torque in your torso rotation and generate power in the arm-torso rotation and the release at the wrists. Mike Austin is another instructor who emphasizes wrist release. The physics bear him out, not only in the power generated, but in the swing path it promotes.

These results are supported by Jorgensen. In his examination of the golf swing, physicist Jorgensen emphasizes the "pull of the left shoulder on the left arm." If you "throw it over the top" or "go outside the line" you are initiating the swing with the right shoulder. And you are releasing the wrists early, thus slowing the rotation of the arms about the shoulder through the negative torque reaction.

By pulling with the left shoulder, he means pulling the club handle back from the top along the swing plane. Thus, the initial pull at the shoulder is backward from the eventual flight of the club through the ball.

If you start the swing with the right shoulder, you have no chained torque reaction through the swing segments, a bad swing path and a glancing strike on the ball. This produces little power. You are putting all your hope on torso rotation and we know that generates little relative to a good release and a swinging of the arm about the shoulder. So, start the swing with a pulling of the left shoulder on the left arm. Drop the hands, release fully 2/3 thirds of the way down and around, and walk through it while retaining your central axis of rotation. The geometry of the swing will be better and you will have far more power even though your swing looks slower.

Sounds easy. I can't wait to try it when my softball, snowboarding, motorcycling, fooling around hurts are fully healed.

· Sports

Comments

I have something to add that is both a comment and a question. Sure would appreciate your posting this and hopefully some comments/amswers to the question.

As to the torso generating a lower power than the shoulders and wrists, if the torso is just spun, yes agreed. However, as mentioned by another posted comment, a real key to he shoulders having this power is from the shoulders first resisting and the torso/hips turning some to add more torqe. Then the shoulders release (with CONNECTED arms to the torso) the power is released. Think of a spring. Backswing is a coil with hips steady as much as possible. Then torque the spring more by lower torso coil. Then shoulders/arms connected spring releases. Proper hip torquing is the key. not spinning the hips, but staying in balance with weight (sitting on bar stool position) and keep back foot on the ground!!! - A lateral move of the hip with the back foot on the ground torques the hip proper. Just keep the arms connected to the body (triangle)and let the coil release by itself!! Arms rotation and wrist release is very imprortant for power. However, this happens by itself due to proper ball position and proper grip. The left shoulder is not pulling the left arm. That would be like pulling a coil sprng!

The proper hip torqing mentioned is slight. If over done, the hips out race the upper torso and never allows the coil to release until too late, which results in a pull hook.

Proper grip, stance,Balance: Then proper slight hip torque (hip lateral with back foot planted), connected arms, auto release of coil/arm rotation and wrists.

Question: Tempo - how can I apply this slight hip torque at the proper speed and time? Right now I actually try to coil just a bit more as I do the lateral hip move with back foot planted, then stay into the shot on balance and auto release everything. this produces 300 yard plus drives consistant. I would like some comments please!! - on proper hip timing.

Posted by: Steve at June 14, 2007 7:19 AM

Posted by: Flower Online at September 11, 2006 2:15 PM

I agree whole-heartedly with the key to power being in the "pulling sensation" of the left shoulder. I learned the golf swing on my own - doing research and basically "digging it out of the dirt". Anyway, consistency and power come from first making a complete shoulder turn on the backswing. This is because I want my left shoulder to be tought (muscles fully coiled). Then, without releasing any of that "coil" I shift my hips laterally ever so slightly before rotating them. It is exactly the same lower body motion as a pitcher throwing a baseball. This is to keep the tight coil in that left shoulder-arm relationship a bit longer and also keeping the right shoulder "inactive". Then, keeping my arms and hands fairly passive, I allow the uncoiling and release of my hips and upper body. This action "ka-flings" the arms/hands/club lever tearing through the impact zone. This is the only way I see that you can consistently hit powerful, crisp and consistent golf shots! It is a thing of beauty, such a violent action yet under control.

Posted by: scripkilla at April 22, 2006 7:40 PM

..surely aside from the walking and the intermittent swings in an actual game, the rote repeticious practise these fellas do, is exactly the thing one would try to avoid ? Am asking....

Posted by: simon FELLOWS at June 17, 2005 12:16 PM

Dear Art
I havn't played golf in a long time but I've heard that Tiger Woods suffers from a bad back from time to time.Too much hip rotation maybe.
Sincerely
Barry

Posted by: barry bocchieri at June 17, 2005 11:33 AM

..Gents/Sir off topic so sorry.
Anyone have any idea about stretching/yoga and insulin sensitivity, please ?

Posted by: simon FELLOWS at June 17, 2005 11:28 AM

Torque and Power in the Golf Swing

June 16, 2005 04:13 PM

Comments

Post a comment