Pros Vs Joes

In the March 2007 edition of Golf Digest, they used a "state of the art" swing analysis device including sensors placed on the body, club, ground, et cetera to measure a players swing "energy". I found the results interesting.

The break down is as follows:

Pro Body Weight Amateur

90% Applied back foot at top 50%
of backswing

110% Of body weight applied to 65%
front foot at start of downswing

25% applied to both feet at impact 50%

It would seem that the pros really push of of their front foot at the start of the downswing. They also talked about the degree of seperation betweenn hip and shoulder and with the pros it was more pronounced - a good seperation was 21 degrees and a poor seperation was 8 degrees.


James

hi
how can you apply 110% of your body weight when you only have 100% max to start with. if your body weight is 100 to start with where does the other 10% come from.
i hate it when people talk about giving 110% when 100% is the max. when i swing a golf club its at about 80/90% and that means i have a little more i can give if i really need it but i cant swing at 110%.
i do take the point you make on the rest of what you say and the pro's do have such good timing the the extra seperation is always controled.
bill

If 25% of the pro's body weight is on each foot at impact, where is the other 50%?

Jeff.

when you jump, before you leave the ground your feet are still touchig. so when you are pushing off the ground you will be decreasing the amount of your body weight that is on the ground and when you finally leave the groud you will have 0% when you land the impact will be greater then your body weight. If a pro is only at fifty percent that is because some weight is being directed upwards.
look at pictures of sam sneead and tigers squat, this directs force down into the front foot at the start of the downswing, then they direct force back up in a reaction to that and you may see pictures where they look like they jump out of their shoes.
look at the feet of these players at/around impact, especially natalie, jenifer, and laura http://images.google.com/imgres?imgu...%3Den%26sa%3DG
Let me know if I explained that clearly enough, sometimes very hard to type what you understand in your mind

I think the weight shift above and below 100% is due to the centripetal force the player applies. Since he can't react as quickly as the clubhead loses speed at impact, he jumps up because of the centripetal force he's been applying to the club by pushing down with his legs.

Centripetal force is a force applied toward the center. In this case, it's toward the center of rotation of the swing. The player applies this force with his hands mostly but he must apply this force against something, that something is his legs and feet planted firmly on the ground.

As the player swings the club, the club may appear to weigh as much as 60 pounds right around impact because of its centrifugal acceleration and opposite centripetal force. Now because of the opposite centripetal force that must be equal to that otherwise we'd call it throwing, we must add this weight to the total weight of the player on his feet. That's probably where the 110% comes from.

As he strikes the ball, the club loses speed in the process and the player doesn't need to apply so much centripetal force to hold it in his hands but he still does apply this much force because he's not so quick that he can ease up as fast as the club loses speed during impact. As this is happening, the extra centripetal force that the player applies is transformed instead in an upward motion: He jumps.

The greatest centripetal force is obviously applied upward at the moment of impact so the greatest reactions to that would surely happen during that time.

It's easy to see at this point how a professional player would fare against an average player. The professional player would apply much more centripetal force so his apparent weight would increase and decrease by much more during the swing than the average player's.

That may not be exactly what happens but that's what I think anyway.

I read something like that from a few places such as Tiger Woods' How I Play Golf and Leslie King's method. The sensation of pushing down with the right foot or something along those lines.

Sorry about that post - when I typed it I had headings, and the proper spacing but it was lost in the post! I was wondering about the same things you were wondering about. In order to get 110% of the weight on the front foot - I think you would have to be pusing off of the front foot as you accelerate the club down. I have seen footage of some long drivers and just after impact one or both of their feet was off of the ground - remarkable. I posted that video here before.

The numbers I reported are the ones I got from the magazine.

James