Ground reaction forces / angular momentum

[Kevin Shields]

Mandrin,

Great stuff as usual--thanks! Your point regarding redistributing forces is a great way to regard the swing IMO. I believe I recall a post from some time ago that mentioned the potential of accelerating the club by braking the pivot...essentially redistributing proximal forces to the distal attachment by intentional braking or retarding the pivot as the club approached impact.

Baseball season fast approaches here in the US. I had my son experiment with this idea in the batting cages. Instead of pivoting faster in response to a faster pitch he intentionally stalled his pivot once he initiated the swing...the bat flew inline much quicker and he was able to non nonchalantly handle the fastest pitching the batting cages could muster. Amateur baseball players often respond to faster pitching by pivoting faster..this results in a dragging attachment...they need to redistribute and listen to Mandrin.

Agree 100%. Good post

 

[teeithigh]

this begs the ? should we consciously brake the pivot to speed up the clubhead and if so how do we do this?

 

[tobell]

Don't want to thread-jack

Teeithigh,

I suggest that you use the search feature to find previous discussions on this topic. I apologize for starting a tangent that threatens to jack this thread. Mandrin's posts are always extraordinary and I for one would like to minimize any friction that may hinder his future contribution.

In your search you'll find gems like this from Mandrin;

"As soon as a club starts to accelerate angularly in the down swing it exerts a braking torque back on the arms. The faster the down swing the greater this braking torque. Hence the idea some seem to have that by exerting more effort it will somehow mysteriously go away is erroneous. Release and braking are like Siamese twins discussing chicken and egg problems."

 

[teeithigh]

thanks tobell cause i remember nicklaus in the 80's talking "reflexive unhinginging" saying he would try to keep his left arm pit snug to his chest to slow his arm down to release better....sounds like "pivot braking" or bmanz analogy of pushing the shopping cart faster by stopping your legs and extending your arms....same ideas right?

 

[tobell]

"Reflexive Hinging"

Teeithigh,

Never heard that "reflexive hinging" concept from Nicklaus before...thanks. My immediate response to it was Mike Austin's figure 7 concept...keep the lead arm in a figure 7 relative the the shoulders through impact...keeps you connected to your pivot.

I tend to think more in terms of retarding the pivot by slowing hip rotation...I'm sure it's a personal choice/style issue...but it's nice to know that there is some scientific validity to the general concept that the pivot slows as its energy travels outward toward the club. To quote Mandrin "It's a chicken and egg argument". My thoughts are that in a well synchronized swing, where the pivot and power package assembly (arms, hands and club) are well coordinated/sequenced you can play with Mandrin's idea of "redistribution". It's a athletic response, a dance, once you sense the acceleration forces from the attachment begin to retard the pivot you can then intentionally "redistribute" energy from the pivot back toward the attachment..you'll definitely feel some connection from the ground through the club...this redistribution seems to connect the ground to the club-head when done properly.

 

[Dustin Smale]

Mr. Nicklaus's Thoughts on Reflexive Hinging

Teeithigh,

Never heard that "reflexive hinging" concept from Nicklaus before...thanks. My immediate response to it was Mike Austin's figure 7 concept...keep the lead arm in a figure 7 relative the the shoulders through impact...keeps you connected to your pivot.

I tend to think more in terms of retarding the pivot by slowing hip rotation...I'm sure it's a personal choice/style issue...but it's nice to know that there is some scientific validity to the general concept that the pivot slows as its energy travels outward toward the club. To quote Mandrin "It's a chicken and egg argument". My thoughts are that in a well synchronized swing, where the pivot and power package assembly (arms, hands and club) are well coordinated/sequenced you can play with Mandrin's idea of "redistribution". It's a athletic response, a dance, once you sense the acceleration forces from the attachment begin to retard the pivot you can then intentionally "redistribute" energy from the pivot back toward the attachment..you'll definitely feel some connection from the ground through the club...this redistribution seems to connect the ground to the club-head when done properly.

Here is a link I found of Mr. Nicklaus talking about hinging of the wrists being a product of "the ever-increasing momentum of the club head." I love the name of the topic, Stop Being a "Loser."

My Golden Lessons Golf Tip of the Week - Faults and Fixes - Stop Being a "Loser"

 

[drewyallop]

Mandrin,

Need some help onthe original post:

1. What is a "ground reaction force"?

2.Why is there no conservation of angular momentum in the golf swing?

3 What is "internal most proximal torque"

Drew

p.s. how are you finding Chalmers? PM me with your thoughts if you like.

 

[drewyallop]

Mandrin,

I am not sure how your analysis fits with Brian's assertion earlier that the pivot contributes only about only about 15% to clubhead velocity. I admit that I could be incorrectly linking redistributive torque with pivot.

Drew

 

[mandrin]

Mandrin,

Need some help onthe original post:

1. What is a "ground reaction force"?

2.Why is there no conservation of angular momentum in the golf swing?

3 What is "internal most proximal torque"

Drew,

1. What is a "ground reaction force"?

Forces don't exist in isolation. They always come in pairs. Every action force is associated with an reaction force, along the same line of action, but in the opposite direction.

For instance – when the clubhead strikes a golf ball there is a force exerted on the ball but the ball exerts an equal and and opposite force on the clubhead.

Ground reaction force similarly refers to the reaction force, the earth exerts on you, due to the action force you exert on the earth with your weight.

Standing still correspond to the static ground reaction force. But moving and rotating body parts cause dynamic ground action forces and consequentially equal and opposite ground reaction forces, acting through the feet/ground interface.

Forces are vectors and are specified with both a magnitude and a specific direction in space. Just standing still, the action/reaction forces, acting through the feet/ground interface, will be very close to vertical in direction

As soon as you start creating internal torques between various body parts then also horizontal ground action force components are generated between the feet/ground interface, resulting in action/reaction torques primarily through the leverage arm between the two feet.

By moving the body briskly down or up, or even both sequentially like Tiger, one dynamically generates larger vertical action ground forces, hence creating more friction between feet and earth, allowing to generate more ground action/reaction torque without slip.

2.Why is there no conservation of angular momentum in the golf swing?

To conserve something you have to have some entity to be conserved. However on the onset of the down swing a golfer has no angular momentum whatsoever. He starts generating it as he progresses into the down swing.

In the last portion of the down swing there is also some redistribution to the clubhead. A Bobby Jone's type 'free wheeling' swing maximizes this transfer, whereas a forceful muscular hitting action diminishes this redistribution.

3 What is "internal most proximal torque"

The muscles acting on the various bones create torques at the joints, ankles, knees, hips, spine, shoulders, elbows, wrist and fingers. The golfer forms a kinetic chain where the ground is referred to as 'proximal end' and the clubhead as the 'distal end' of this chain.

One can consider body torques, such as for instance associated with the wrists, by themselves, but also how these body generated torques do create torque relative the earth via the feet/ground interface. The most distal wrist torque generates negligible ground torque whereas the combined action of ankles, knees, legs and hips creates a large proximal torque.

 

[mandrin]

Mandrin,

I am not sure how your analysis fits with Brian's assertion earlier that the pivot contributes only about only about 15% to clubhead velocity. I admit that I could be incorrectly linking redistributive torque with pivot.

Drew

Drew,

I can't not make such an assertive statement with regard to human golfers. This is only possible when one considers a human golf robot where everything would be defined once and for good. It is a kind of statement to be carefully defined and restricted for certain specific type of swings.

Just consider. Keeping arms/wrists like spaghetti, just using lower body for motivating the swing, is dramatically different from a golfer who takes a very short stubby back swing and hits hard primarily using trail arm extension.

My analysis, 'ground reaction force / angular momentum', wasn't meant to accurately represent a golfer but rather try to show some light on this rather obscure notion of ground reaction forces, everyone is referring to freely, but really not understood by many.