McLeans' X factor

[JeffMann]

HF

 

I read that McLean article about the triple X-factor in the GD.

 

I don't think that there is much new - its only the idea of a dynamic X-factor rather than a static X-factor.

 

I have changed my thinking in the past year. I now think that the idea of a X-factor is junk science. I don't believe that the human body can coil and uncoil - like McLean suggests. If anybody believes otherwise, please explain in anatomical terms what body part is coiling and uncoiling.

 

Consider two examples.

 

Example 1. Imagine golfer A turning his hips 30 degrees while golfer B turns his hips 45 degrees. Both turn their shoulders 100 degrees. According to McLean, golfer A has more static X-factor, and should hit the ball further. If you believe that this is true - explain it in anatomical/biomechanical terms.

 

Example 2. Golfer A and golfer B have a 40 degree hip turn and a 100 degree shoulder turn. However, golfer A turns his hips towards the target before the shoulders have completed the backswing. Golfer A therefore has a greater degree of dynamic X-factor. If you believe that golfer A therefore has greater swing power and can hit the ball further, explain it in anatomical/biomechanical terms.

 

Jeff.

[hoganfan924]

[quote name='JeffMann' post='822371' date='Dec 12 2007, 09:48 PM']HF

I read that McLean article about the triple X-factor in the GD.

I don't think that there is much new - its only the idea of a dynamic X-factor rather than a static X-factor.

I have changed my thinking in the past year. I now think that the idea of a X-factor is junk science. I don't believe that the human body can coil and uncoil - like McLean suggests. If anybody believes otherwise, please explain in anatomical terms what body part is coiling and uncoiling.

Consider two examples.

Example 1. Imagine golfer A turning his hips 30 degrees while golfer B turns his hips 45 degrees. Both turn their shoulders 100 degrees. According to McLean, golfer A has more static X-factor, and should hit the ball further. If you believe that this is true - explain it in anatomical/biomechanical terms.

Example 2. Golfer A and golfer B have a 40 degree hip turn and a 100 degree shoulder turn. However, golfer A turns his hips towards the target before the shoulders have completed the backswing. Golfer A therefore has a greater degree of dynamic X-factor. If you believe that golfer A therefore has greater swing power and can hit the ball further, explain it in anatomical/biomechanical terms.

Jeff.[/quote]

Pretty simple Jeff. Average tour pro's have 17.4 degrees of 'X-factor stretch.' Typical amateurs have 5.9 degrees. Pro's hit the ball a lot further and generate a lot more clubhead speed than the typical 17 hdcp. Tour pro's also have more "static" X-factor as you put it (I don't recall the numbers, I'm sure Points could inform us)

As I've written several times on this site in the last year, I tend to agree that "Static" X-factor as you put it (it's of course not really static, just measured at one point in the swing) is not overall as important as Dynamic X-factor (my term for the combination of "Static" and X-factor stretch) or "X-factor stretch" alone (McLean's term) in generating speed, but [b]both[/b] must be present. If there's no "static" X-factor at the top, a player could create tons of X-factor stretch (for arguments sake, let's say 30 deg.) and not be as effective as a player that has 50 Deg. of "static" X-factor and an additional 20 deg. of X-factor stretch. In biomechanical terms, you have to elongate a muscle before you can produce motion by contracting that muscle. The more a muscle is elongated, the more distance it can contract. The more distance it can contract, the more work it can produce and power it can create.

Here are the physics equations: Force x Distance = Work. Force applied without motion produces no work. Therefore a muscle applying a contractile force over a longer distance produces more work. Work/Time = Power. The more power you can generate and transfer to the club, the more clubhead speed. The muscles in question in this case IMO, would likely be the Transverse abdominus, Latissimus Dorsi, Rhomboids, Hip adductors, glutes, Psoas major, obliques and probably a few more (but please correct me if I'm mistaken as I'm not a Doctor). The more those muscles stretch, the more work and power they can produce.

Is that a sufficient "biomechanical argument" for your tastes? Not junk science at all.

I know I've seen a swingvision close up at some point of Tigers midsection. You can very clearly observe his pelvis rotating forward in the downswing while his shoulders are still moving back. Would post it, but couldn't find it.

Also Jeff, concerning coil: The pelvis rotates relative to the feet. The shoulders rotate relative to the pelvis. The muscles elongate. There's your coil.

[Veritas]

In addition to Hoganfans talk about the increased distance the muscles can produce work over there is also an additional argument beyond just the muscle contracting over a longer period. The muscles in addition to the tendons and ligaments are going to be stretched as you create the x factor. Each of these components can be thought of as a spring and are storing energy as you stretch them more. Due to the elastic nature of these components once the load is removed from the spring they will return to the original position and release the stored energy. Thus, the larger the "x-factor" produced, the more energy you are going to store in your muscles, ligaments, and tendons that will be released upon swinging. As a result of the distance the muscle can contract and the energy stored due to the elastic nature of the materials, I think there is a very sound biomechanical reasoning for this theory.

Note: I think the muscles are going to be your predominant contributors in this situation compared to the ligaments and tendons.

[kosmosspoetz]

McClean is not my favorite teacher, but.... He has collected data using a K-Vest type of device. His first one (CIRCA 1993-4) was designed by Mike McTiegue, but I can't remember the name of it. What he found was that long hitters have a bigger X-factor than short hitters. This new article is just an update.

I hit with the old system a bunch. It just measures what you do. How do you argue with that?

[hoganfan924]

[quote name='rdbivyleagun' post='822441' date='Dec 12 2007, 10:36 PM']In addition to Hoganfans talk about the increased distance the muscles can produce work over there is also an additional argument beyond just the muscle contracting over a longer period. The muscles in addition to the tendons and ligaments are going to be stretched as you create the x factor. Each of these components can be thought of as a spring and are storing energy as you stretch them more. Due to the elastic nature of these components once the load is removed from the spring they will return to the original position and release the stored energy. Thus, the larger the "x-factor" produced, the more energy you are going to store in your muscles, ligaments, and tendons that will be released upon swinging. As a result of the distance the muscle can contract and the energy stored due to the elastic nature of the materials, I think there is a very sound biomechanical reasoning for this theory.

Note: I think the muscles are going to be your predominant contributors in this situation compared to the ligaments and tendons.[/quote]

I agree to a point, but an elongated muscle doesn't act like a spring until it is to it's point of maximum elongation, but rather, it behaves more like a linear actuator.

[Lake]

[u]Search for the Perfect Swing[/u] p.80

[i]Man's muscles are not themselves elastic. When stretched, they just stay stretched, until they are told to contract. Sinews and tendons can provide just a little elasticity at the top of the backswing; and this may indeed make some small contribution to the power of the forward swing. But the main power of the forward swing must come from positive muscle action.[/i]

[JeffMann]

HF - I find your argument very unconvincing.

Let me start off by analysing your statements.

You state-: "Average tour pro's have 17.4 degrees of 'X-factor stretch.' Typical amateurs have 5.9 degrees. Pro's hit the ball a lot further and generate a lot more clubhead speed than the typical 17 hdcp."

You are trying to posit a cause-and-effect relationship here wiithout presenting any evidence to establish a solid causal relationship. It is true that pros hit the ball further than the typical 17 handicap amateur golfer. However, there are many potential reasons for this fact. To establish a causal relationship between a "cause" (eg. variations in X-factor) and an "effect" (longer driving distance), you have to prove that the causal relationship is unequivocal. There are many other potential causes for an [b]effect[/b] of longer driving distance in a pro golfer eg. better synchrony/sequencing/timing/greater athleticism/greater lag. With all those[b] potential causes[/b], how can one establish that variations in X-factor plays any significant role. Also consider pro golfers who have a classical swing style, like Sam Snead and Phil Mickelson. They have a low X-factor and hit the ball a long way. Sam Snead probably rotated his hips 60 degrees and his shoulders 110 degrees, and had little static/dynamic X-factor, but he hit the ball a long way.

You state-: "In biomechanical terms, you have to elongate a muscle before you can produce motion by contracting that muscle. The more a muscle is elongated, the more distance it can contract. The more distance it can contract, the more work it can produce and power it can create."

I regard your reasoning as entirely flawed. A muscle doesn't have to be elongated beyond its resting length to contract optimally. Consider an example - the biceps muscle in the arm. If the arm is held alongside the body so that the arm hangs naturally, the biceps is already at its natural length. It will contract optimally from that resting position. One doesn't get the biceps to function better by elongating it beyond its natural length. In fact, if one elongates a muscle beyond its natural resting length, it may function far less optimally, because it may be over-stretched.

Consider another line of reasoning - presume that the hips turn 40 degrees and the upper body (shoulders) turns 100 degrees. That will cause stretching of the external abdominal muscles. During the downswing, those muscles will contract and help rotate the mid-torso. If the hips only turn 30 degrees, those muscles will be stretched slightly more. Does that imply that they will function more optimally and turn the mid-torso with greater force because of that 10 degree difference? If you believe that fact, then you would need to provide proof. I believe that as long as the external abdominal muscles are operating within their "effective" contractile range, they will contract equally effectively. Also, the idea that tendons/ligaments will snap back faster if stretched is a total fallacy - because they have little elastic tissue and are incapable of being stretched. Therefore, any slight variations in the degree of muscle stretch will have minimal effect on the snap recoil properties of their tendinous attachments. Tendons cannot store energy when a muscle is stretched, and they therefore cannot release energy.


You write-: "Here are the physics equations: Force x Distance = Work. Force applied without motion produces no work. Therefore a muscle applying a contractile force over a longer distance produces more work. Work/Time = Power. The more power you can generate and transfer to the club, the more clubhead speed. The muscles in question in this case IMO, would likely be the Transverse abdominus, Latissimus Dorsi, Rhomboids, Hip adductors, glutes, Psoas major, obliques and probably a few more (but please correct me if I'm mistaken as I'm not a Doctor). The more those muscles stretch, the more work and power they can produce."

According to your physics equation, work output = force X distance. You are therefore presuming that the work is useful work. It is only useful when it is aligned with the purpose under consideration. Consider Sam Snead' swing. He turned his hips a lot (? 45- 60 degrees), which means that he stretched certain muscles more than a golfer who only turns his hips 30 degrees (eg. Tiger Woods), while at the same time stretching other muscles far less. You would have to demonstrate which muscles are being stretched/shortened and whether it affects the ability of those muscles to contract optimally in such a way that it [b]actually[/b] increases torso rotating power, and therefore clubhead speed. Good luck in solving that problem, and proving that any differences in clubhead speed are due to differences in "effective" muscle work output rather than due to variations in body alignments, and synchrony/sequencing of body movements that accompany different swing styles eg. classical swing style of Sam Snead versus lower body swing style of Tiger Woods. Also, you loosely refer to muscles like the psoas major/hip adductors/gluteal muscles. Do those muscles become more stretched in golfers who have a large X-factor, or are they shortened?

Jeff.

[Veritas]

[quote name='hoganfan924' post='822506' date='Dec 12 2007, 11:24 PM'][quote name='rdbivyleagun' post='822441' date='Dec 12 2007, 10:36 PM']In addition to Hoganfans talk about the increased distance the muscles can produce work over there is also an additional argument beyond just the muscle contracting over a longer period. The muscles in addition to the tendons and ligaments are going to be stretched as you create the x factor. Each of these components can be thought of as a spring and are storing energy as you stretch them more. Due to the elastic nature of these components once the load is removed from the spring they will return to the original position and release the stored energy. Thus, the larger the "x-factor" produced, the more energy you are going to store in your muscles, ligaments, and tendons that will be released upon swinging. As a result of the distance the muscle can contract and the energy stored due to the elastic nature of the materials, I think there is a very sound biomechanical reasoning for this theory.

Note: I think the muscles are going to be your predominant contributors in this situation compared to the ligaments and tendons.[/quote]

I agree to a point, but an elongated muscle doesn't act like a spring until it is to it's point of maximum elongation, but rather, it behaves more like a linear actuator.
[/quote]

I don't disagree with you, however, most of the muscles that are relevant to this discussion are going to be in an elongated state during the x-factor and store energy in an elastic manner in addition to the ligaments and tendons. For this reason, it is completely relevant to talk about the spring effects of the muscle at this point. This is why if I do a torsional stretch like that which would be seen in creating the x factor or any other stretch for that matter, when I release the load my body will pull back some without any contraction of additional muscles. To clarify though, I am not disagreeing with your original point, I am only trying to add even further reasoning why the x-factor has a biomechanical basis.

[Veritas]

Jeffman, you say that tendon and ligament can not store energy. This is without question 100% false. I am doing a PhD in Biomechanics and Orthopaedic Tissue engineering at Cornell University and I deal with the mechanics of tendon and ligaments on a daily basis. We run mechanical testing on tendons and ligaments and I watch these tissues stretch and recoil to their original position demonstrating elasticity all the time. The tendons and ligaments are for sure strong tissues but most definitely do exhibit elastic behaviour.

If tendons don't have elasticity and muscle contraction don't do anything to tendon elasticity then you better contact these researchers and let them know they are wasting their time. [url="http://jap.physiology.org/cgi/content/abstract/91/1/277"]http://jap.physiology.org/cgi/content/abstract/91/1/277[/url]

[Veritas]

[quote name='lake' post='822516' date='Dec 12 2007, 11:36 PM'][u]Search for the Perfect Swing[/u] p.80

[i]Man's muscles are not themselves elastic. When stretched, they just stay stretched, until they are told to contract. Sinews and tendons can provide just a little elasticity at the top of the backswing; and this may indeed make some small contribution to the power of the forward swing. But the main power of the forward swing must come from positive muscle action.[/i][/quote]

Sorry the statement that muscles are not elastic is not true. Muscles do show elasticity. When I handle muscle in the lab and I pull on it, it certainly does not stay stretched but returns to the original position. Here is an article even talking about a protein that plays a key role in muscle elasticity.

[url="http://www.scienceblog.com/community/older/1999/D/199903685.html"]http://www.scienceblog.com/community/older.../199903685.html[/url]

However, I don't disagree that the main power comes from muscle action. My point about the elasticity is just to show that there are elastic contributions in a stretched system such as seen in the x-factor.

[JeffMann]

Rb---

I am amazed that you would refer to such an irrelevant journal article in an attempt to make a point.

If you are indeed as well-educated as you claim, then you should easily be able to provide some relevant figures. Consider the movements involved in a golf swing. Consider a golfer who has a hip rotation of 30 degrees versus a hip rotation of 45 degrees, presuming a "fixed" shoulder rotation of 90 degrees. Consider those different degrees of hip rotation and their effect on the X-factor. The golfer with a larger X-factor presumably has torso muscles/tendons that are more stretched. Could you please tell me which [b]particular[/b] torso muscles/tendons are more stretched? Specifically, could you please give me actual figures for the relevant viscoelastic properties of those [b]particular[/b] muscles and their tendons, and show me that that the [b]tendons[/b] are in fact stretched to such a degree that they can store, and release, elastic energy - if the degree of hip rotation only varies by 15 degrees (30 degrees versus 45 degrees). I would also be interested in any proof that any elastic stretch of those particular muscles (in contrast to any elastic stretch of any tendons) adds significantly to the rotating torso power of those muscles, which I believe is primarily due to their active/positive muscular contracting power.

Jeff.

[proguy]

All I know is that when I make a fuller turn away from the ball I have a much more dynamic swing and hit the ball farther. That is fact.

[jaridyard]

Jeffmann, I was about to structure a cohesive answer addressing your question but realised that I'm not really interested in becoming part of yet another one of your arguments/debates as you seem to be constantly fire fighting.

In brief however of course the body can't coil, that's just an unfortunate choice of words. Yes there is such a phenomenon as stretch induced force enhancement, the amplitude of which is determined by the length/force relationship of the muscle. When comparing an active contraction with that of a stretched active contraction there will be only one winner. Is it necessary to prove which muscles experience this in the golf swing? Not really.
The goal of attaining a dynamic X factor would certainly help with correct implementation of the kinetic chain and achieving peak velocity at the correct points. Returning to your original post and example 2, it is highly likely that a golfer who initiates the downswing hip rotation before the shoulder rotation is complete will have a great swing power. If not because of the stretch induced force then certainly because of the better kinetic chain.

b*llocks....I guess that makes my opening statement null and void.

[kosmosspoetz]

JeffMann,

The original data for the X-factor was a comparison of professional golfers. Approx 150 players. The longest hitters had the largest x-factors. Some had small hip turns and less than 90 degree shoulder turns, but had large differentials. Daly had a big hip turn and an huge shoulder turn. Shorter hitters like Bob Estes had smaller x-factors. I'm not sure that the use of the data was biomechanically sound. They taught restricting the hip turn to maximize the X-factor. I think it is more useful to think of starting the downswing from the ground up with the idea of developing pivot lag.

[jaridyard]

[url="http://www.golflink.com/instructor/mcmaster/pdf/oct2002.pdf"]http://www.golflink.com/instructor/mcmaster/pdf/oct2002.pdf[/url]

Go to section 5, have a read. Then contact Rob Neal for a debate.

[jeffy]

[quote name='JeffMann' post='822371' date='Dec 12 2007, 09:48 PM']HF

I read that McLean article about the triple X-factor in the GD.

I don't think that there is much new - its only the idea of a dynamic X-factor rather than a static X-factor.

I have changed my thinking in the past year. I now think that the idea of a X-factor is junk science. I don't believe that the human body can coil and uncoil - like McLean suggests. If anybody believes otherwise, please explain in anatomical terms what body part is coiling and uncoiling.

Consider two examples.

Example 1. Imagine golfer A turning his hips 30 degrees while golfer B turns his hips 45 degrees. Both turn their shoulders 100 degrees. According to McLean, golfer A has more static X-factor, and should hit the ball further. If you believe that this is true - explain it in anatomical/biomechanical terms.

Example 2. Golfer A and golfer B have a 40 degree hip turn and a 100 degree shoulder turn. However, golfer A turns his hips towards the target before the shoulders have completed the backswing. Golfer A therefore has a greater degree of dynamic X-factor. If you believe that golfer A therefore has greater swing power and can hit the ball further, explain it in anatomical/biomechanical terms.

Jeff.[/quote]

I don't recall the names of the specific muscles that stretch and recoil in the golf swing, but they have been pointed out to me a few times by my physical trainer and I could easily show them to you. However, before heading down that path, let's step back a minute. McLean identifies three areas where it can be observed that the best golfers are in dramatically different positions than "average" golfers (x-factor, hip rise and head swivel). These observed differences are obviously the consequence of the pros [b]DOING SOMETHING DIFFERENT[/b] in the downswing. McLean then explains what these different moves are, and how they can contribute to more power.

Your characterization of McLean's thesis is, at best, misleading. It is a typical [i]straw-man[/i] argument by you where you falsely attribute a weak position to another person so you can then easily debunk it. McLean doesn't at all "suggest" that the good golfer winds up like a spring, then just let's go. He clearly illustrates the [b]ACTIONS[/b] the better golfers make in the downswing, and has compiled statistics of a few key positions to show the magnitude of the differences between pros and amateurs. Snead once said something along the lines that "good positions don't create good swings; good swings produce good positions". McLean amply demonstrates this in his article. Please stop starting threads so you can rip others for things they didn't say.

[christhebigsmokemoss]

I'm kinda on JeffMans side here.

I dont believe that you can hit it further with less hip turn to try to generate more power.

Check the links out below the first few are guys with alot of hip turn and the second lot are the guys with restricted hip turn. They all crunch the ball stupid distances but use different techniques.

Distance comes fom fast twitch muscel fibre!


[url="http://www.youtube.com/watch?v=bNP51zXn_qk&NR=1"]http://www.youtube.com/watch?v=bNP51zXn_qk&NR=1[/url]
[url="http://www.youtube.com/watch?v=PVs0tkmAkro&feature=related"]http://www.youtube.com/watch?v=PVs0tkmAkro...feature=related[/url]
[url="http://www.youtube.com/watch?v=0h-5zCB4Lzw&feature=related"]http://www.youtube.com/watch?v=0h-5zCB4Lzw...feature=related[/url]

[url="http://www.youtube.com/watch?v=579vKnXxzSI&feature=related"]http://www.youtube.com/watch?v=579vKnXxzSI...feature=related[/url]
[url="http://www.youtube.com/watch?v=3eOt9iGPzbY&feature=related"]http://www.youtube.com/watch?v=3eOt9iGPzbY...feature=related[/url]

[hoganfan924]

[quote name='christhebigsmokemoss' post='822707' date='Dec 13 2007, 08:17 AM']I'm kinda on JeffMans side here.

I dont believe that you can hit it further with less hip turn to try to generate more power.

Check the links out below the first few are guys with alot of hip turn and the second lot are the guys with restricted hip turn. They all crunch the ball stupid distances but use different techniques.

Distance comes fom fast twitch muscel fibre!


[url="http://www.youtube.com/watch?v=bNP51zXn_qk&NR=1"]http://www.youtube.com/watch?v=bNP51zXn_qk&NR=1[/url]
[url="http://www.youtube.com/watch?v=PVs0tkmAkro&feature=related"]http://www.youtube.com/watch?v=PVs0tkmAkro...feature=related[/url]
[url="http://www.youtube.com/watch?v=0h-5zCB4Lzw&feature=related"]http://www.youtube.com/watch?v=0h-5zCB4Lzw...feature=related[/url]

[url="http://www.youtube.com/watch?v=579vKnXxzSI&feature=related"]http://www.youtube.com/watch?v=579vKnXxzSI...feature=related[/url]
[url="http://www.youtube.com/watch?v=3eOt9iGPzbY&feature=related"]http://www.youtube.com/watch?v=3eOt9iGPzbY...feature=related[/url][/quote]

Chris, I am in agreement that you don't hit it further with a restricted hip turn. But that's not what X-factor is all about. It's about maximizing the differential between hip and shoulder turn, not to be artificially created by restricting hip turn. I've written about that here before. IMO, the most important "X-factor" is ensuring that the X-factor is maximized during the early downswing. I believe McLean's research completely aligns with that point of view.

Unfortunately, after the first X-factor article was published, many golfers (and I imagine at least a few instructors) mistakenly believed that restricting hip turn was the way to increase and effectively utilize X-factor. They were wrong and McLean addressed this in a follow-up article a few years later. Now he's added to that knowledge even further and I have no reason to doubt his main premise. With swingvision, it is easy to see this "X-factor stretch" in great golfers. I recall seeing a close-up of Tiger's midsection on swingvision but can't seem to find it again on youtube. That close-up demonstrates perfectly what McLean has documented in his research.

[Points]

Jeffmann,

I am going to make this very short. Jim has written several articles, two DVD's, and a book on the X factor. If you follow any number of papers written by the bio mechanical field on the golf swing, Jim's X factor is usually cited as a source of research. What the X factor is, is simply looking at the relationship between shoulder and hip turn in the golf swing and their relationship with distance. It is not intended to create 10 degree of hip turn and 100 degree of shoulder turn as some might believe. A fairly real example is guy that has a hip turn of 30 and shoulder turn of 60 hits it distance A. If we are able to increase his hip turn and shoulder turn to say 35 and 70, he will hit it further. Very simple to do the test. Use a motion movement machine and a launch monitor.

What is very sad about this post, is that Jeffman reads an article in a magazine and got on a forum to discredit the teacher's life work. This is not the first time you have done such a thing. Unlike the previous case, there is a mountain of information out there for you to look into before you ever post your rather misinformed opinion. When I post anything about another theory or swing, I always look into what the teacher says. Has the media latched onto some key phrase to summarize this person's work. Do I see the ideas that the person is in professional swings?

The X factor remains on going study on how the body works in terms of moving parts. There must be something to the whole idea as we have seen an onslaught of bio mechanics in golf since the original article. TPI, Pittsburgh Institute of Sport, K Vest, Rob Neal, and many more continue to research and define this relationship.

Jeffman, in your expert opinion how is power created in the golf swing? I am sure you will cite lag as a major power source which is very limited as your arms and hands can only hit the ball so far. Maybe power comes from weight shift only. If this is the case, why do so many golfers turn? Maybe, just maybe power is created through four power sources. The hands, the arms, the turn, and the weight shift.

[christhebigsmokemoss]

Living in London i dont know much about baseball, but was wondering if they implement the same X Factor thories to help them get more power for their homers?

[caryk]

[quote name='Points' post='822711' date='Dec 13 2007, 08:31 AM']The X factor remains on going study on how the body works in terms of moving parts. There must be something to the whole idea as we have seen an onslaught of bio mechanics in golf since the original article. TPI, Pittsburgh Institute of Sport, K Vest, Rob Neal, and many more continue to research and define this relationship.[/quote]

Points,

Back in 1999, Golf Tips magazine ran a series of terrific articles by Jeff Parks at GolfTEC on the mechanics of the swing using computerized data and anatomical representations. It was great stuff and featured precise information as well as their interpretation of it. I still have the articles. Just wish there was an easy way to create a link to them through the Golf Tips website but unfortunately, I don't think they still have them in their database. I could scan them but there's alot of pages to the articles. The GolfTEC data did a nice job of correlating to McLean's initial X-Factor ideas.

Suffice it to say, there's been alot of sophisticated research by some pretty smart people on the mechanics of the swing over the years. I guess it's up to each individual to decide whether to believe the results of all this hard work or not.

Cary

[slicefixer]

I normally try and stay out of "these" threads, but, I would like to state one thing........

IMOP, like him or not, Jim McClean is one of the best in my business, period. His X Factor research and subsequent publication of his findings are without a doubt some of the most revealing and thought provoking EVER published in regards to our game. Jim McClean is NOT afraid to state a position, UNLIKE a LOT of SUPPOSED "big names," (and accept the subsequent criticism) and then BACK IT UP with formal research, unlike some who "hide in the shadows" or, even worse, state a position, WON'T explain it, WON'T reveal the HOW/WHY/WHERE in regards to their conclusions, etc. etc. etc (the "snake oil salesman")......I can tell you this, I've read EVERYTHING McClean's EVER published and simply can't find "fault" with ANYTHING he's ever stated. I have an old black binder (I call it my "golfswing bible") that's literally STUFFED with magazine articles, pictures, etc. that I believe represent what I believe and teach every day. Some of the articles date back to the late 60's. Without a doubt Jim McClean's articles/research make up the largest % of information in it. I can also say that I can't disagree with ANYTHING Jim McClean has EVER stated in print. My own "ideal"/preferred swing "type" has less lateral motion than Jim advocates, but, there is STILL lateral motion present just as Jim suggests, just less of it and you don't have to think about it to create it. Anyway, I'm not going to get into the debate regarding "the elasticity" of a muscle as I don't feel I can contribute anything fact based/intelligent to the conversation. It IS an interesting debate and I CAN "see" BOTH sides......

[JeffMann]

Jared - You stated-: "Yes there is such a phenomenon as stretch induced force enhancement, the amplitude of which is determined by the length/force relationship of the muscle. When comparing an active contraction with that of a stretched active contraction there will be only one winner. Is it necessary to prove which muscles experience this in the golf swing? Not really."

I will initially deal with your first statement. You state that there is such a thing as stretch-induced force enhancement. I agree. However, is it [b]biomechanically significant[/b] in the torso-powering of a golf swing. I doubt it!

Consider a simple analogy. Imagine a person in a gym doing quadriceps knee extension exercises against a load of 160 lbs. I presume that you have seen those gym machines where a person can sit with the leg bent at right angles and pull/push the front of the lower leg against a bar so that the knee joint straightens fully. When pulling against the bar, a system of pulleys controls the resistance of the bar and it is set at 160 llbs. Now imagine a stop being set so that the leg doesn't go back to a 90 degree bend at the end of the relaxation phase, but the stop stops the leg from bending further when the knee is bent at 70 degrees. Then imagine a scientist measuring the work output of the quadriceps muscles during the knee extension exercise, and also the efficacy of the knee extensor action. In the situation where the knee is bent to 90 degrees (rather than 70 degrees) the quadriceps is obviously stretched further. Do you really believe that the quadriceps muscle is going to work better because it has that additional amount of pre-contracticle stretch? If you do believe that fact, can you quantitate how much of the work output is due to stretch-enhanced force enhancement.

To those who believe that tendons can stretch elastically and thereby store and release energy. In the above exeriment, the patellar tendon is being stretched during the relaxation phase of the knee extension exercise. Do you believe that the extra 20 degrees of knee bend allows the patellar tendon to elastically stretch more and thereby store more energy, and that this additional energy can contribute [b]significantly[/b] to the work output in the next knee extension movement? If you believe that fact, could you please provide scientifically-valid evidentiary support for your belief.

Jared - you state that this stretch-induced force enhancement is present in the golf swing, but you don't think that you need to prove that fact. That's the difference between junk science and real science. In real science, one has to prove facts via rigorously designed scientific experiments where one has minimised the effect of confounding variables. D--- states that he has a PhD in biomechanical engineering. Hopefully his expertise will allow him to provide the necessary scientific proof for the benefit of all interested forum members. I would like to know which torso muscles are being stretched in a swing where the X-factor is 20 degrees greater in golfer A (compared to golfer B), and how much of that torso muscles subsequent activity is due to stretch-induced force enhancement. I am also hoping that he will mention which tendons are being stretched during this muscle stretching process, and how much they store energy that can be released when the relevant torso muscles subsequently contract and rotate the torso.

Points - if there is a mountain of scientific research material out there can dispel my belief that the idea of the X-factor is really based on junk science, rather than real science, then hopefully you (or another forum member) can quote the relevant scientific research. You also asked me how power is generated in a golf swing. I think that a lot of swing power comes from torso rotation secondary to active torso muscular contractions. What I am contesting is the belief that stretch-induced force enhancement plays a [b]significant[/b] role in the ability of these torso muscles to generate swing power.

Jeff.

[Veritas]

[quote name='JeffMann' post='822584' date='Dec 13 2007, 01:25 AM']Rb---

I am amazed that you would refer to such an irrelevant journal article in an attempt to make a point.

If you are indeed as well-educated as you claim, then you should easily be able to provide some relevant figures. Consider the movements involved in a golf swing. Consider a golfer who has a hip rotation of 30 degrees versus a hip rotation of 45 degrees, presuming a "fixed" shoulder rotation of 90 degrees. Consider those different degrees of hip rotation and their effect on the X-factor. The golfer with a larger X-factor presumably has torso muscles/tendons that are more stretched. Could you please tell me which [b]particular[/b] torso muscles/tendons are more stretched? Specifically, could you please give me actual figures for the relevant viscoelastic properties of those [b]particular[/b] muscles and their tendons, and show me that that the [b]tendons[/b] are in fact stretched to such a degree that they can store, and release, elastic energy - if the degree of hip rotation only varies by 15 degrees (30 degrees versus 45 degrees). I would also be interested in any proof that any elastic stretch of those particular muscles (in contrast to any elastic stretch of any tendons) adds significantly to the rotating torso power of those muscles, which I believe is primarily due to their active/positive muscular contracting power.

Jeff.[/quote]

Jeff,

I am first going to attempt to not be offended by this post. I understand your skepticism of internet claims but I assure you I am doing the degree that I said that I am doing. If you want to PM me I will give you further proof of this if you so desire it.

Second, I am not sure why you consider the journal article irrelevant. It was not meant to prove the x-factor as true. It was a quick way to show some evidence that tendon is an elastic material which you claimed in a previous post that it was not. What I don't understand is why in one post you claim that tendon as inelastic and then you state it has viscoelastic properties identifying it as an elastic material in another. I don't know why if you know that tendon is a viscoelastic material why you would claim it is not an elastic material. This leads me to believe that I must be misunderstanding what you are saying and that you are not actually saying tendon is not elastic but something else. I'm sorry but when someone types out that tendon is not an elastic material I am going to respond in disagreement.

Third, I would like to make it clear that of course the muscle contracting is providing most of the power. I am not saying that it is not. In all of my posts I have been trying to say that the elastic strain could also contribute as well. I was simply trying postulate an additional parameter that could be contributing to the X-factor providing greater power.

Fourth, I do not have off the top of my head the exact values that you are looking for in these specific muscles and their tendons. I know that tendons range in modulus from 1.2-1.8 GPa but as to the specific tendons in the golf swing I can not give you without doing a literature search. Nor do I know what loads would be imposed on these tissues in a golf swing. My area of research is not the tendons and muscles involved in the golf swing but with the Intervertebral Disc. If you want values off the top of my head for the IVD I will surely do it but that is not relevant here. It's very possible the experiments that one would need to have done to know the data you are looking for simply have not been done at this point. If I get a chance I will do some searching through the literature to see if I can come up with some values to either disprove or prove the effects of the elastic storage of energies affects on the golf swing.

Finally, I think there might be some confusion as to what is being said about the x-factor. I don't think anyone is saying that it is 100% what causes the power one sees in the swing. I think what they are saying is that it is a contributing factor. Just because I go out and increase my x-factor to that of some of the big hitters doesn't mean I'm going to all the sudden hit it just as far as them, but I probably will hit it farther than I was. There most definitely is going to be many other contributing factors including fast muscle twitch, hand eye coordination, etc. All those are going to come into play and effect how far you are going to hit the ball. It is very common in biological/human systems for their to be a great deal of variation and many contributing factors. What would be interesting is to see some research that documents the degree of x-factor compared to the driving distance over a large population and see if there is any correlation that way. Maybe this has been done?

Robby

PS. Jeff I think if you can avoid attacking me I would probably be very willing to help you investigate this further. I have no big hold onto the x-factor teaching. I have only been golfing for a little over a year now and thought that you asking for biomechanical theories for why this might work would be fun to look at and a post that I could contribute to due to my field.

[slicefixer]

[quote name='christhebigsmokemoss' post='822738' date='Dec 13 2007, 10:00 AM']Living in London i dont know much about baseball, but was wondering if they implement the same X Factor thories to help them get more power for their homers?[/quote]


There is a LOT of "crossover" between the MODERN "big muscle" golf swing and the MODERN "baseball swing".........both are CORE based......the difference being in the golf swing your "unwinding" around your LEFT leg/left pivot point and it's more or less VERTICAL......In baseball it's "around" a more rightward pivot point (in a righty).........BOTH are inherently ROTATIONAL.........the "speed" comes from the INSIDE-OUTwards...........Bond's is the ultimate IMOP as he can hit for POWER and AVERAGE.........

[Points]

Jeff,

I am actually very confident in my stance and I am sure that if you do just a little homework on your own you will find the information you are looking for. You can always start with the sources listed above ie TPI, Pittsburgh Medical Institute of Sport, Golf Bio Dynamics, and all of the DVDs, books, and articles by Jim. As far as I can tell, my argument is supported by others while yours is simply your limited opinion.

[JeffMann]

HF

I presume that this is the video of TW that you are talking about.

[url="http://www.youtube.com/watch?v=4wxn0sIkJH8&mode=related&search="]Tiger Woods Driver Swing[/url]

In that video, one can sense that TW is using a considerable amount of mid-torso muscle power to power his swing. The question then becomes, how much of that mid-torso generated power comes from pure muscle contraction and how much comes from stretch-induced force enhancement. I strongly suspect that TW could generate similar amounts of torso-generated swing power if his static or dynamic X-factor was reduced slightly - without limiting the length of his backswing.

TW obviously hits the ball a long way. However, Mike Austin apparently hit it a lot further. He reputedly drove a ball 515 yards in competition. Here is a swing video of MA's driver swing (look at the first 4 swings performed when he was very young and at his peak). Note that he doesn't have a swing that is designed to maximise the X-factor (either static or dynamic), and that he has a free flowing hip turn in both the backswing and downswing. Are you implying that he would hit the ball further if he changed his swing style to have more Xfactor (either static and/or dynamic)?

[url="http://www.youtube.com/watch?v=IoqZufP3UJc&mode=related&search="]MIke Austin Driver swing[/url]


Jeff.

[Points]

Jeff,

By posting the Mike Austin swing, you show a clear lack of understanding as to what the X factor is. Both Tiger and Austin, have huge x factors. By that I mean, the difference between the amount of hip and shoulder turn. The biggest x factor doesn't mean you hit it the furthest. In fact, you can have too big of an X factor which makes it difficult to create power as well as be consistent. One of the things looked at in the recent article is the stretch during the start down. I have no idea what Austin's numbers are but I would venture to say that they would be very comparable to other top hitting long professionals. There are other factors which go into the strike as well. Clubhead speed, weight shift, strength etc.

[hoganfan924]

[quote name='JeffMann' post='822808' date='Dec 13 2007, 10:15 AM']HF

I presume that this is the video of TW that you are talking about.

[url="http://www.youtube.com/watch?v=4wxn0sIkJH8&mode=related&search="]Tiger Woods Driver Swing[/url]

In that video, one can sense that TW is using a considerable amount of mid-torso muscle power to power his swing. The question then becomes, how much of that mid-torso generated power comes from pure muscle contraction and how much comes from stretch-induced force enhancement. I strongly suspect that TW could generate similar amounts of torso-generated swing power if his static or dynamic X-factor was reduced slightly - without limiting the length of his backswing.

TW obviously hits the ball a long way. However, Mike Austin apparently hit it a lot further. He reputedly drove a ball 515 yards in competition. Here is a swing video of MA's driver swing (look at the first 4 swings performed when he was very young and at his peak). Note that he doesn't have a swing that is designed to maximise the X-factor (either static or dynamic), and that he has a free flowing hip turn in both the backswing and downswing. Are you implying that he would hit the ball further if he changed his swing style to have more Xfactor (either static and/or dynamic)?

[url="http://www.youtube.com/watch?v=IoqZufP3UJc&mode=related&search="]MIke Austin Driver swing[/url]


Jeff.[/quote]

I strongly believe you are incorrect. Guess we'll once again have to agree to disagree. Mike Austin? Are you serious? Yes, he hit one 515, with a 40 mph tailwind and downhill! What the heck does that prove about X-factor? BTW, he had a considerable amount of it. You can even see some X-factor stretch in that video.

[caryk]

HF,

Can you PM me (your mailbox is full)? Didn't realize we have something in common.

Cary