|
Post by utahgolfer on Mar 29, 2020 16:49:10 GMT -5
The kinematic sequence tracings provides the evidence that the left arm is moved mostly by the shoulder turn during the first half of the backswing and the first half of the downswing. This is illustrated as the pelvis, thorax, and left arm move at similar speeds during the first half of the backswing and first half of the downswing. The kinematic sequence tracings also show that the left arm moves more independently during the second half of the backswing and the second half of the downswing. This is illustrated as the left arm begins to move faster than the pelvis and thorax during the second half of the backswing and second half of the downswing. What we see happening during slow motion video parallels what we see illustrated on the kinematic sequence tracings. The nature of left arm motion during the swing is based on the premise that during a given movement, proximal motion is more dominant during the initial stages and distal motion is more dominant during the later stages. The same is true with forearm rotation (supination and pronation) and the wrist hinge (ulnar deviation and radial deviation). All distal body motion happens more in the second half of the backswing and downswing, respectively. Some instructors say to "start the downswing from the ground up" which is acceptable because it promotes a proper kinematic sequence. One could say the same for the backswing. But, this is a little vague and makes it sound like the feet and lower legs is where the swing starts, which is not exactly correct, since this is a distal part of the body. In reality, proximal isometric core muscle activation is what occurs first before any noticeable body motion. Any body motion requires a stable foundation from which to move from, and core muscle activation occurs first. The feet and legs provide a stable fixture on the ground, which is essential, but this is not where the golf swing begins. With enough core muscle activation and stabilization, body movement can begin, but this movement is also proximal and should first include muscle activation to move the pelvis and lower torso. It would be better to say, "start the swing with the pelvis to move the rest of the body". Of course, when the pelvis turns, this turns the spine, which turns the shoulders, which moves the arms, all because of skeletal inter-connection and coordinated muscle activation. Consequently, the whole idea is to swing more proximal (inside) during the first half of the backswing and downswing, and to swing more distal (outside) during the second half of the backswing and downswing. It is obvious that the pelvis and deep core should be the starting point of any proper movement, when we walk, run, jump, or swing. During the backswing, the first movement should begin by rotating the pelvis and core, which immediately begins to rotate the spine in the same direction. The left arm should follow the lead of the body. Consequently, during the first half of the backswing, the left arm follows the lead of the pelvis and shoulders, but during the second half of the downswing, the left arm moves more on its own. The same is true with any left forearm rotation (pronation) and wrist cocking (radial deviation)--most of this happens during the second half of the backswing. Ideally, we should move primarily from inside out, from proximal to distal, as we swing. The same concept applies for the downswing. The first movement should begin by rotating the pelvis and core, which immediately begins to rotate the spine in the same direction. The left arm should follow the lead of the body. The left arm only begins to move faster than the pelvis and shoulders during the second half of the downswing. Again, this is when most left forearm rotation (supination) and wrist uncocking (ulnar deviation) should also occur--during the downswing's second half. These swing mechanic principles are fundamental, and are the basis of a proper kinematic sequence. This should be taught during a golfer's first lesson and repeated many times. The dog's core wags the tail. A dog's tail does not wag the core. The same is true in the golf swing, and any whole body human movement pattern. UG
|
|
|
Post by dubiousgolfer on Mar 29, 2020 19:00:17 GMT -5
Hi UG Not sure about your idea regarding the kinetic sequence of the backswing. If you look at Phil Cheethams article below: www.philcheetham.com/media/Basic-Biomechanics-for-Golf-Selected-Topics-by-Phil-Cheetham-2014.pdf THE TAKEAWAY SEQUENCEIt is common for most good ball strikers to begin their takeaway sequence with the club first, followed by the arms, chest and then hips. This is not always the case, but the key point is not to let the hips start the motion. Having the correct takeaway sequence will aid the golfer to create a good transition as shown in Figure 8. Figure 8. Takeaway Sequence. The graph shows that the club moves first because it has the fastest initial backswing velocity and pelvis last because it has slowest backswing velocity. DG
|
|
|
Post by utahgolfer on Mar 29, 2020 20:26:09 GMT -5
DG, none of what I've said applies to the golf club itself, only the pelvis, thorax, and left arm. The key in the takeaway is how the pelvis, thorax, and left arm all move together, with the left arm speeding up last. The slight increase in club speed is minor and only reflects that a slight amount of wrist motion is speeding up the club during the takeaway. The premise that the global swing begins around the pelvis is logical and accurate, whether it involves the backswing or the downswing.
UG
|
|
|
Post by utahgolfer on Apr 2, 2020 14:14:29 GMT -5
Milo Lines also discusses this athletic motion concept in this video:
Proximal to distal motion creates the most effective early hand speed and on-time club head speed.
UG
|
|
|
Post by imperfectgolfer on Apr 2, 2020 17:12:39 GMT -5
Milo Lines also discusses this athletic motion concept in this video: Proximal to distal motion creates the most effective early hand speed and on-time club head speed. UG Stop Milo's video at the 5.58 minute time point when the two pro golfers are reaching their P5.5 position. Note that their right elbow is far away from the right side of their torso due to a very slow right arm adduction maneuver. Now, look at Rory McIlroy's right arm adduction speed.
Note that his right arm is fully adducted against the right side of his torso by P5.5 due to a very fast right arm adduction maneuver (which I think is a major factor that increases hand speed between P4 => P5.5).
Jeff.
|
|
|
Post by utahgolfer on Apr 3, 2020 23:14:05 GMT -5
Jeff, I have the opposite opinion on this topic.
I still don't see how independent right arm adduction is a major factor in early hand speed in a player who has normal hula hula flexibility and an elite pivot. It is hard for me to believe Rory makes any overt attempt to pitch his right elbow or any attempt to move it fast. He has one one the fastest hip rotation speeds and probably one the the fastest upper torso rotation speeds, too. Of course, there is some independent right arm adduction, but the right arm gets closer to the right side primarily due to the shoulder turn. Rory has a fast shoulder turn, therefore his left arm moves quickly toward the target. Rory has a fast shoulder turn, therefore his right arm gets closer to his right side quickly. Any independent right arm adduction is in a micro-move category, with minor significance. Rory's fast pivot has to be what is determining his fast early hand speed from p4 to p5.5.
Any golfer can display fast independent right arm adduction. Only elite players have elite hula hula flexibility and blazing fast pivots. A flexible player with elite pivot speeds does not need to worry about pitching the right elbow at a fast speed. It will happen primarily due to the pivot. Of the two, I would predict sufficient right arm external rotation is more important. It automatically creates some right arm adduction and sets the pitched elbow, at the same time. But, sufficient right arm ER is still a micro-move that most players can do, and micro-moves do not distinguish the hack from the elite.
Even DJ's prominent right arm adduction is a micro-move. It only looks prominent due to his amazing flexibility, and his elite pivot motion. It can't be why he is an elite golfer.
If you take the elite pivot motion away from an elite golfer, any micro-move is never going to make up the difference.
My mantra is that the pivot rules!
UG
|
|
|
Post by imperfectgolfer on Apr 3, 2020 23:33:52 GMT -5
UG, You wrote-: " I still don't see how independent right arm adduction is a major factor in early hand speed in a player who has normal hula hula flexibility and an elite pivot. It is hard for me to believe Rory makes any overt attempt to pitch his right elbow or any attempt to move it fast. He has one one the fastest hip rotation speeds and probably one the the fastest upper torso rotation speeds, too. Of course, there is some independent right arm adduction, but the right arm gets closer to the right side primarily due to the shoulder turn. Rory has a fast shoulder turn, therefore his left arm moves quickly toward the target. Rory has a fast shoulder turn, therefore his right arm gets closer to his right side quickly. Any independent right arm adduction is in a micro-move category, with minor significance. Rory's fast pivot has to be what is determining his fast early hand speed from p4 to p5.5." Here is Rory's 3-D kinematic sequence graph. The blue graph is his left arm's angular velocity graph. Note that it is moving faster than his upper torso's angular velocity graph (green graph) from very early on in the downswing and continuing throughout the P4 => P5.5 time period. The slope of the blue graph is even steeper than the slope of the green graph, implying a faster acceleration speed that causes the gap between the two graphs to increase before both graphs reach their peak values at roughly the same time. How do you explain that "fact" if the left arm is simply being pulled along by the rotating upper torso, which moves the left shoulder socket targetwards?
Jeff.
|
|
|
Post by syllogist on Apr 4, 2020 5:01:09 GMT -5
Dr. Mann,
I think that the answer to the torso/left arm velocity difference is because the left arm is longer than the width of the torso, of course, depending on where markers are placed. If, for example, the left arm rotates at the same rpm as does the torso, the angular velocity of the left arm as measure at the wrist joint will be greater than that of the torso. The velocity of a distal point of a line segment is greater than that of a proximal point.
In any event, I personally don't think that right arm adduction is a significant factor in initial left arm hand speed.
S
|
|
|
Post by imperfectgolfer on Apr 4, 2020 9:45:03 GMT -5
Dr. Mann, I think that the answer to the torso/left arm velocity difference is because the left arm is longer than the width of the torso, of course, depending on where markers are placed. If, for example, the left arm rotates at the same rpm as does the torso, the angular velocity of the left arm as measure at the wrist joint will be greater than that of the torso. The velocity of a distal point of a line segment is greater than that of a proximal point. In any event, I personally don't think that right arm adduction is a significant factor in initial left arm hand speed. S I think that you are totally wrong! Angular velocity is a measure of the change in the angle, which means that every point along the length of the left arm will be traveling at the same angular velocity, even if the linear velocity of a peripheral point on the left arm is traveling faster than a more proximal point. Angular velocity is basically a measure of the rpm. Jeff.
|
|
|
Post by dubiousgolfer on Apr 4, 2020 10:40:19 GMT -5
Hi S
The y axis of that graph above is the degree of angular displacement vs time (x-axis). Therefore the slope is the angular velocity (the rate at which angular displacement changes over time) and one can clearly see that the blue graph (left arm) is rotating faster (ie. its angular velocity) than the torso (green graph) very early in the downswing.
Oops mistake :
The left arm is rotating faster than the upper torso, therefore it seems that the shoulder girdle muscles are actively being utilised in the early downswing.
DG
edit 19/05/2020
Got the above wrong so struck through- The y axis of the graph was angular velocity while x-axis time. Therefore the slope represents angular acceleration as per Dr Mann's previous post
|
|
|
Post by dubiousgolfer on Apr 4, 2020 11:08:24 GMT -5
I have been looking at this 'Sandtrap' thread where there is obvious disagreement between what powers the golfswing. Look at Erik Barzeski comment below (I think that's his name) - who I also think is a 'PGA Pro Instructor' using the poster name called IACUS thesandtrap.com/forums/topic/97118-speed-from-the-arms-in-the-golf-swing/?do=findComment&comment=1418272Then also look at the you-tube by Martin Hall Its strange that the golf industry in our high tech age still cannot decide 100% what powers the golf swing. DG PS. Not sure what he meant by the following (I might register and ask him). "'ll be honest: I'd typed out a whole long paragraph explaining how this graph demonstrates that the arms are doing a LOT of work against the platform the chest ( not only to maintain the chest's acceleration but to further accelerate the arms beyond that, and ultimately the bottom of the double pendulum - the shaft of the club), but I'm not sure you'd get it, and I've already spent way too much time on this. "
|
|
|
Post by utahgolfer on Apr 4, 2020 23:11:33 GMT -5
I played golf with Jeff today and he helped me to see the value of the right arm adduction maneuver. One example is to swing with the left arm only and to notice how fast the left arm moves from p4 to p5.5, and then to repeat this with both hands on the club with the addition of the right arm. Not only does the right hand provide stability and help guide the hand arc path, but the right arm adduction maneuver increases the hand speed from p4 to p5.5. Another important insight is that the right arm adduction maneuver shouldn't be applied beyond p5.5, since this can over-accelerate the left arm into impact and not provide sufficient time to release PA#2.
Of course, we all agree that the pivot is what drives the master power accumulator #4, but the right arm adduction maneuver is important when applied correctly and is an integral part of the swing.
Just for fun, check out Kyle Berkshire great pivot, right arm adduction maneuver, and the release of PA#4 and PA#2. What a beast!
And, check out his hyper-extended left leg at 0:22. Crazy!
UG
|
|
|
Post by syllogist on Apr 5, 2020 6:38:56 GMT -5
Dr. Mann,
You're absolutely correct - my error in using angular. Also I didn't release that the graph wasn't pure velocity.
DG,
There's a youtube video (https://www.youtube.com/watch?v=GbQPc-hMgBc) that shows Gears marker placement. If we use the orientation of the back of the left hand as an example of avatar error, I noted that there is no marker placed on the back of the left hand. The closest marker is on the wrist joint in line with the back of the left hand. I don't know whether the marker placements have been changed since this video but I have a thought that might involve certain measurements:
I'm thinking that a marker only shows position in space and, if the marker is on something that just spins axially, its position in space does not change. I don't know what Gears does to account for this type of rotation (e.g., rotation of left hand).
S
|
|
|
Post by dubiousgolfer on Apr 5, 2020 7:21:45 GMT -5
|
|
|
Post by dubiousgolfer on Apr 5, 2020 7:43:40 GMT -5
Hi UG
looking at the left leg extended for KB where he might be using GRF forces to increase clubhead speed (ie. parametric acceleration) but I don't think its very large (but obviously important for long drive competitions).
Strangely enough , I was looking at JS's swing here on 3D Gears and checked out his 'Grip Speed' on the video below .
Some things I noticed were:
1. Around P5 his speed was approx. 25.91 mph 2. Around P6.5 his speed drops to 21.02 mph (as PA#2 releases - clubhead increases speed , while his grip speed drops) 3. At around P7 his speed increases to 24.51 mph
In several other golfers on Gears, the grip speed keeps dropping after PA#2 release but in JS's case , he upped it by about 3.5 mph .
So the 'jumping up' and snapping of left leg extension (that Tiger used to do) maybe to utilise 'Parametric Acceleration' effect doesn't seem to add much clubhead speed .
DG
Correction 20/05/20 - At P7 his grip speed was about 22.7 mph so he kept his Grip speed virtually unchanged until impact. Then it jumped to 24.51 mph as residual clubhead energy started moving from club to arm post impact.
|
|