McLeans' X factor

[JeffMann]

Robby - I will be happy to argue these points with you if you are willing to be a little more dispassionate and if you are willing to consider a different interpretation of the same data. I am not asking you to agree with me. I am only asking you to reflect carefully before you respond again.

You state that there is a strong correlation between the degree of torso-pelvic separation and ball speed, while you state that there is a much weaker correlation between shoulder turn angle and ball speed. Now, I suggest that you consider interpreting the same data in terms of simple common sense logic - taking into account some common sense knowledge of human biomechanics. In that study there was a [b]biomechanically[/b] insignificant difference in the degree of hip turn angle at the end-backswing (44.9 degrees for the HBV group and 49.8 degrees for the LBV group). That's only a 5 degree difference. From a "real life" biomechanical perspective, I would regard these two values as being roughly the same in terms of [b]clinical significance[/b] - by clinical significance, I mean their "real life"significance as applied to the "real" world of human golf biomechanics. A golfer who turns his hips 45 degrees rather than 50 degrees is not making a significant change. By contrast, the biggest difference accounting for the maximum degree of shoulder-hip separation at the end-backswing position is the difference in shoulder turn angle - which was 94 degrees in the LBV group and 104 degrees in the HBV group. Therefore, if any single component accounts for the difference in hip-shoulder separation values at the end-backswing position, then it is the difference in the degree of shoulder rotation.

Regarding the idea of using correlation coefficient values to study the relationship between a single result (which I will call for simplicity sake a "cause" or "[b]independent variable[/b]") and another measured single result (which I will for simplicity sake call an "effect" or "[b]dependent variable[/b]"), I think that it is useful only for studying[b] possible[/b] causal relationships where the causal connection is likely to be [b]simple[/b] (due to a single factor), rather than[b] complex[/b] (due to a multiplicity of factors). Therefore, common sense dictates that one shouldn't use a[b] simple [/b]correlation coefficient value to study relationships when one knows 'a priori' (based on common sense knowledge of the golf swing) that there likely is a complex interaction between the hip turn (lower body movement) and the shoulder turn (upper body movement) in a real life golf swing. SF can tell you that efficacy of performance of the hip turn in the downswing will have a marked influence on how efficiently the upper body subsequently turns in the downswing, because the lower and upper body are closely/synchronously connected in a good golfer, while they are far more disconnected in a poor golfer. I therefore regard the placement of[b] major interpretative emphasis[/b] on [b]single[/b] correlation coefficient values unwise.

You state that the degree of shoulder turn does not affect ball speed that much on its own and that it is therefore a "non-factor in the discussion". I think that's a huge mistake because you have not run correlation coefficient values for[b] multiple interactions[/b], and it is therefore irrational to claim that it has no causal role in ball speed on the basis of a single correlation coefficient value for a simple relationship. Common sense dictates that their[b] may[/b] be a causal connection between the combination of hip turn velocity in the downswing and maximum shoulder turn angle in the backswing. That study did not perform a complex statistical analysis to study that type of complex causal interaction. I believe that if a good golfer, like Tiger Woods, has the athletic ability to generate a fast hip turn in the downswing, that it may have a synergistic effect when combined with a 10 degree greater shoulder turn (104 degrees instead of 94 degrees) in the backswing - because the power of the lower body torquing action is transmitted to the upper torso and when the upper torso eventually catches up to the hips in the late downswing, the benefit of an additional 10 degrees of shoulder turn may become apparent. In other words, it may not be causally apparent that an extra 10 degrees of shoulder turn angle at the end-backswing position is important if studied via the use of a single correlation coefficient value (designed for simple relationships), but it may be very apparent to a good golfer, who has the capacity to perform a perfectly executed shoulder/hip downswing action, that an extra 10 degrees of shoulder turn [b]may[/b] be highly significant.

I also find it strange that you regard the degree of shoulder turn at the end-backswing not worthy of discussion (not a factor) but then invoke its obvious presence when discussing theoretical interpretative explanations. You state-: "Movements that involve a stretch –shortening contraction utilize stretching active muscles (eccentric loading) to load the muscle in order to increase power output during the final phase of the movement (concentric shortening) (Komi, 1984, 2000; Norman & Komi, 1979). Ultimately, a muscle that is eccentrically loaded before a concentric contraction results in increased force and power production compared with an isolated concentric or eccentric muscle contraction." What causes eccentric loading of the torso muscles other than a significant degree of hip-shoulder turn angle difference at the end-backswing position? In that study, the hip turn angle difference between the two groups was only 5 degrees, while the shoulder turn angle difference was 10 degrees, so the shoulder turn angle difference was 2x as important to this [b]difference in the degree of eccentric loading[/b] than the hip turn angle difference. Therefore, your discounting the importance of the difference in the shoulder turn angles at the end-backswing position makes no sense when it comes to that theoretical explanation. Let me take it one step further. You state-: "The increased force production is a result of utilization of elastic energy within the muscle –tendon unit during the eccentric loading of the active muscle that is released during the concentric phase of the movement." I will label that theory explanation number 1. How do you know that explanation number 1 is the [b]best [/b]true explanation ("true" being understood from a Popperian perspective - according to the scientific principle of having a low falsifiability factor)? If the torso muscles are eccentrically loaded by a greater amount in the HBV group, then it also means that they are more elongated due to the greater degree of shoulder rotation (10 degrees more in the HBV group). That provides a second theoretical explanation to account for the fact that the upper body rotation in the HBV group was much faster in the early downswing (738 degrees/second for the HBV group and only 546 degrees/ second for the LBV group). Explanation 2 is based on the fact that an elongated muscle will allow for a greater degree of [b]active [/b]muscle shortening per unit time and therefore be able to generate [b]more force per unit time[/b] (remember that the HBV group golfers have a combination of more elongated torso muscles due to a 10 degree greater degree of shoulder rotation and they can also complete their early downswing phase in the same time period, or even shorter time period, than the LBV group) to get to the [b]same[/b] measurement position - lead arm parallel. Expressed in another manner, both groups of golfers had to get to the lead arm parallel position (which was the end of their [b]early[/b] downswing measurement point) but the HBV group golfers' more elongated torso muscles had a further distance to travel (10 degrees extra shoulder turn). I therefore think that the HBV group could generate faster upper torso rotation speeds at that measurement time-point due to [b]increased efficacy of active muscle contraction [/b]during the early downswing phase ( efficiency = actively shortening a greater length of muscle in the same time period) that has nothing to do with the passive utlization of elastic energy stored within the muscle. Why is explanation number 2 not more rational than explanation number 1? You stated-: "There is the scientific evidence that a stretch induced increase in force is seen within muscle." Wrong. You are automatically favoring explanation number 1 when making that claim! We only know that the torso muscles are more elongated in the HBV group compared to the LBV group - we do not automatically know if the increase in early dowswing power that results in greater upper torso rotational speeds during the early downswing is due to stretch-induced force enhancement of muscle contraction (due to the elongation) or whether it is due to increased active muscle force generated during the downswing.(due to elongation that allows for a greater degree/efficacy of [b]active [/b]muscle shortening per unit time). A different type of experimental design would be needed to test the scientific validity of explanation number 1 versus the scientific validity of explanation number 2. You are only demonstrating your 'a priori' bias by favoring explanation number 1 over explanation number 2.

Finally, you state-: "A p value can be interpreted like this. p = .05 means that there is a 5 % chance that the result occurred by chance." I think that you are misunderstanding the true meaning of a p value <0.05. A scientific experiment is done to test the null hypothesis, and the null hypothesis is that there is no difference between the two experimental groups. I think that the true definition of a p-value <0.05 is as follows-: A p-value <0.05 means that there is a <1/20 chance that one will obtain a result as large, or larger than the experiment's observed point estimate result - under the assumption that the null hypothesis (that there is no difference between the two groups) is true - if the experiment is repeated many times. From a definitional perspective, one 'a priori' assumes that the null hypothesis is true, and the p-value estimates what's the chance likelihood of getting a result as large, or larger than the point estimate result, if the experiment is repeated multiple times. It doesn't mean that there was a 5% chance of getting that [b]specific [/b]point estimate result.

Jeff.

p.s. For other forum members' benefit - LBV = Low ball velocity, while HBV = High ball velocity

[Texsport]

Relative to the importance of rotational speed/power in an individual golf swing, it would make sense that it is more critical as a power source in a rotary, body reliant style swing than in a more upright, arms reliant swing.

If so, making generalizations about the X-Factor is difficult.

As mentioned previously, the amount of speed lost in the downswing is vital.

I've observed that upright swingers generally employ lateral movement and arm force(pulling) to generate power to compensate for their narrower swings. Since lateral movement on the downswing would seem to scrub off rotary speed, it would seem to follow that the X-Factor is not so important with this type swing.

Indeed, if I'm not mistaken, Nicklaus, certainly an upright swinger, advocated as much hip turn as possible in the backswing.

Conversely, in wider, rotary swings, with little lateral movement, the X-Factor may be more useful.

What say you group?

Texsport

[Veritas]

Jeff,

Wow it is 5 in the morning and I just erased a huge response I had written which took almost 2 hours to craft. I think we are getting ourselves into an argument that really doesn't have an answer in that you are correct or that I am correct because I believe we both are correct. This was the conclusion I came to after spending way too much time thinking about the papers results and the postulated arguments here. I really didn't want to erase the response because I wanted to defend my self and my reasoning. ( I would like to say though that I do understand what a p value is very well and in my attempt to simplify the understanding for everyone I left out a key interpretation of what I meant by the word "result". (pride can only be put down for so long )). I think we could argue back and forth on the appropriate time to use correlations and how to use them but I don't think that is the most useful information that my experience can contribute into this discussion or the way we are going to actually get to any answers on this question.

What I want to say is that I think what you are describing with the lower body turn and shoulder turn is actually an additional factor to how the x-factor is contributing to the swing speed. The simple shoulder turn without separation from the from the pelvis will lead to a poor transfer of power to the upper torso from the lower body rotation due to the lack of tension in the muscles. However, with increased x-factor this energy will be better transferred. As a result, I don't see any reason why this wouldn't contribute to increased ball speed with an increased x-factor. If you think about the swing as 2 cylinders with one being the pelvis and the other being the upper torso then if the two cylinders are separate then you get no additive properties of speed as they both rotate. But if they are connected, which would be facilitated and increased by an increase in x-factor then you can basically ad the velocity of both cylinders together. It's like the idea of being on a train going 60mph and throwing a ball off the train with an initial velocity of 60mph resulting in a speed relative to the ground of 120 mph. The only difference here is the velocity is rotational.

I also believe how ever that there is plenty of evidence to support the idea of increased force production through the stretching of the muscles and tendons. The data is there that this phenomenon is seen in muscles and I think its just as reasonable to assume this is happening as Jeff's postulations.

Also, the argument of the force and distance that the muscles can work has been brought up is completely valid as well.

And finally, the force vector enhancement that was discussed is also valid.

In the end, what we have are a list of 4 biomechanical factors that are all enhanced when the x-factor is increased and would lead to greater ball speed. I think this gives us a pretty solid list of why biomechanically the x-factor works and why it would be so correlated to ball speed.

Jeff I'm sorry if I was a bit aggressive in my previous post but I do tend to get passionate about things and can come on strong at times.

[hoganfan924]

Robbie,

Great answers. Thanks for your hard work in this thread. There's only one person that should consider apologizing in this thread and it's certainly not you.

Interestingly, the concept of cylinders connected to each other with springs was first published (with a sketch) in 1968 in "Search for The Perfect Swing," and the authors specifically discuss the "unwinding from the ground up" contributing to the development of clubhead speed! Perhaps this was even McLean's inspiration for undertaking X-factor research to begin with.

I think this thread has worn out it's usefulness and you response summarizing things was dead on.

[Points]

With all the evidence mounting, I find it amazing that the Doc cannot admit that he was wrong.

[birdie_man]

Haven't read all of this but.....I take it that some are trying to prove that muscle (and tendon?) stretching adds power. (i.e. like a spring or rubber band)

What comes to my mind is the question:

Do your muscles not stretch at the end of ANY backswing?

...

Example- Sam Snead turned his hips a lot. But his backswing had an end to it just like any golfer in history. I assume that end came when he could turn no more.

Does he get less "stretch" than an "x-factor" player? (i.e. one who restricts the pivot)

BTW I just realized y'all may be talking about "downswing x-factor".........hmmmm.......oh well I post anyway.

[JeffMann]

Robby,

 

I am sorry that you lost so much of your hard work. It has happened to me many times because I did not save my material every 5 minutes while writing a long post using Microsoft Word.

 

Regarding the "correct" interpretation of that paper's results, I don't think that we can both be right. Either you are right or I am right. I was regarded as a mini expert on the interpretative analysis of research papers and I wrote, and taught, many physician-researchers how to analyse research papers. For example, here is post that I wrote for an online discussion forum, when I was debating the correct interpretation of P values with other physician-researchers - the post was so long that I had to divide it into three parts.

 

Part1

 

Part 2

 

Part 3

 

 

Analysing research papers was my speciality, and I was particularly interested in the philosophy of science and how researchers should interpret the results of their research papers. I once developed 10 rules of good scientific practice as it pertains to the correct interpretation of scientific research evidence, and here is one of those rules.

 

1. A scientist should resist the tendency to think inductively - in other words, the scientist should resist any tendency to draw general conclusions from a series of experimental observations (other than the specific conclusion as to whether the observational data supports or contradicts his primary hypothesis); other general conclusions that are not directly connected to the primary hypothesis can be posited in the form of another (separate) explanatory theory that may be suitable for future experimental testing.

 

I personally think that you have broken this rule when adamantly positing an explanation for the result-data published in that study - the theory that the data supported "a stretch-induced force-enhancement of muscle contraction". I believe that one cannot interpret the studys' results in that manner. Even the primary author of the paper was very reluctant to draw that type of conclusion for his own research paper. This is what he wrote in the discussion section of his research paper-: "A cause-and-effect mechanism (ie. increased torso-pelvic separation) causes increased ball velocity was not established." He was not even willing to claim that a large X-factor causes increased ball velocity - based on the results of his own study (because all his correlation coefficient relationships were only in the moderate range), and he was certainly prudent enough not to venture further and claim that he knew the actual mechanism why increased torso-pelvic separation could cause an increase in ball velocity.

 

I personally think that you have not provided any scientific evidence that suggests that stretch-induced force enhancement of torso muscle contraction significantly helps power the torso rotation in a golf swing. To accomplish that goal, you would have to demonstrate how you can scientifically differentiate between two factors that are at play during increased eccentric loading of torso muscles secondary to a large X-factor - i) stretch-induced force enhancement of muscle contraction (which is passive); and ii) increased active muscular contractile force due to the increased muscle elongation that accompanies increased eccentric loading (which is active).

My personal suspicion, based on common sense knowledge of human biomechanics, is that the active force is markedly more important than the passive force.

 

You write-: "The simple shoulder turn without separation from the from the pelvis will lead to a poor transfer of power to the upper torso from the lower body rotation due to the lack of tension in the muscles." I simply cannot understand the significance of this statement. Very few golfers turn their pelvis as much as their shoulders - not even beginner golfers. Most golfers, even high handicappers, turn their pelvis about 40-50 degrees, and their shoulders about 70-90 degrees, and they develop a certain degree of torso-pelvic separation. I think that most low/mid handicap golfers get a greater degree of torso-pelvic separation by getting a greater shoulder turn of at least 90 degrees (and often 100 degrees), and a hip turn of about 40-50 degrees. What is responsible for the increased X-factor - it's a greater degree of shoulder turn, rather than a significant change in the degree of hip turn. Why is this beneficial? On this point we seem to agree. You write-: "However, with increased x-factor this energy will be better transferred. As a result, I don't see any reason why this wouldn't contribute to increased ball speed with an increased x-factor. If you think about the swing as 2 cylinders with one being the pelvis and the other being the upper torso then if the two cylinders are separate then you get no additive properties of speed as they both rotate. But if they are connected, which would be facilitated and increased by an increase in x-factor then you can basically ad the velocity of both cylinders together. It's like the idea of being on a train going 60mph and throwing a ball off the train with an initial velocity of 60mph resulting in a speed relative to the ground of 120 mph. The only difference here is the velocity is rotational." I agree that clubhead speed will be increased if the upper torso works in synchrony with the lower body, so that there is no loose connections (the torso must be structurally taut). However, a good connection between the upper and lower body in the golf swing is not primarily dependent on eccentric stretching of torso muscles and tendons. I think that it is primarily dependent on the correct method of executing a backswing pivot action - which enables the upper body to develop a specific alignment relationship with respect to the lower body, as exemplified by this reverse-K "look" of Hogan's end-backswing position.

 

 

Jeff.

[Points]

"Analysing research papers was my speciality, and I was particularly interested in the philosophy of science and how researchers should interpret the results of their research papers. I once developed 10 rules of good scientific practice as it pertains to the correct interpretation of scientific research evidence, and here is one of those rules."

I find this amazing as you have failed to correctly read posts during this thread.

[slicefixer]

[quote name='Texsport' post='825240' date='Dec 15 2007, 05:59 AM']Relative to the importance of rotational speed/power in an individual golf swing, it would make sense that it is more critical as a power source in a rotary, body reliant style swing than in a more upright, arms reliant swing.

If so, making generalizations about the X-Factor is difficult.

As mentioned previously, the amount of speed lost in the downswing is vital.

I've observed that upright swingers generally employ lateral movement and arm force(pulling) to generate power to compensate for their narrower swings. Since lateral movement on the downswing would seem to scrub off rotary speed, it would seem to follow that the X-Factor is not so important with this type swing.

Indeed, if I'm not mistaken, Nicklaus, certainly an upright swinger, advocated as much hip turn as possible in the backswing.

Conversely, in wider, rotary swings, with little lateral movement, the X-Factor may be more useful.

What say you group?

Texsport[/quote]


I will say this..........an "upright" backswing (above the ideal plane) has 2 choices that will work consistently............

- "Drive laterally" to re-route the arms/club into a position where the player CAN "rotate" and let their CORE ROTATION square up the club "naturally" as a by-product of their ROTATION........(think Nick Price in his prime and Furyk today)

OR

- basically release the club with the ARMS from the top and the CORE is basically just "along for the ride"........like Nicklaus in his prime.........

What you do NOT want to do is a lil' of one and a lill' of the other..........then you end up in a "sword fight with the golf club" in the impact zone trying to square the face..........BAAAAAD "place" ta' be IMOP........2 way misses......INconsistent ballstriking.......etc.

[jaridyard]

I think it's fair to say that this discussion has reached a point at which no further progress will be made.
Certainly one to be revived when somebody can find a published article that supports the hypothesis that stretch induced force enhancement makes a significant increase to the force actively produced during the downswing phase.
Until this time I think it's unfair to decide that somebody was right or wrong, apologies are unnecessary in what has been a debate, not a mudslinging contest.
I for one look forward to finding/being shown the truth.

[Veritas]

Jeff,

I don't even know what to say. I don't know if you have any idea how arrogant you come off on these boards. I have apologized for coming on too strong to you. In other words, attacking you, what I don't mean is that I think my theory is wrong.

You really seem to be misunderstanding what I am saying in my posts.

I stated
"Now to the data and Jeff's theory. First, they showed that there is a large and significant correlation (correlation = .54, p=.001) between Torso-pelvic separation and ball speed. This correlation confirms without a doubt that ball speed is correlated to pelvic-torso separation/xfactor and should not be argued. However, correlations don't mean causation, only that they are somehow related."

I don't claim a cause for the ball speed from their data. Just read above. I state correlation does not mean causation. My talk about torso/hip separation was meant to be postulating that the mechanism could be the extension muscle energy storage. I do not invoke any of the data that they present in this part of my discussion. I present the introduction where they provide references to studies that have shown evidence to this mechanism's possibility. Strong evidence that this mechanism is very possible in this system. I think your inability to accept this as a possible and likely significant contributor shows your own bias.

Second, your inability to see how we could both be right is just evidence that you didn't read or interpret correctly what I was talking about. I wasn't saying our interpretation of the paper was the same but that both our theories about how the x-factor could be correlated to ball speed could both be factors. We can both be right because it is a human system that has many factors working at the same time. It is very easy to envision a system that is both benefiting from the energy transfer of the lower torso pulling on the upper torso, as well as enhanced force production from muscle/tendon energy storage. Your lower body transfers the load to the upper torso causing acceleration of the upper torso while the increased force production from the muscles in the extended state further accelerate the upper torso as well. Both postulated mechanisms occurring at the same time.

You state, "To accomplish that goal, you would have to demonstrate how you can scientifically differentiate between two factors that are at play during increased eccentric loading of torso muscles secondary to a large X-factor - i) stretch-induced force enhancement of muscle contraction (which is passive); and ii) increased active muscular contractile force due to the increased muscle elongation that accompanies increased eccentric loading (which is active)." I don't need to differentiate between the two. I am postulating both of these effects, as they are both a result of increased stretch within the muscles. I take both the active and passive increases to be what I am arguing for. I do recognize that more research needs to be done to further show this in the golf swing and I hope they conduct these studies. However, I have given scientific proof of a possible mechanism while you still rely on your "real life" examples to support your theory. If you have the proof I would love to see it.

You state..."The simple shoulder turn without separation from the from the pelvis will lead to a poor transfer of power to the upper torso from the lower body rotation due to the lack of tension in the muscles." I simply cannot understand the significance of this statement." You support this argument by saying that most golfers turn their hips around 40-50 degrees and in your previous argument you supported this with the means in the data between the HBV, MBV, and LBV groups. This however is a misuse of what the means represent. All that says is that the "average" golfer between the groups is around the same. To truly look at the population and how golfers turn the pelvis you have to look at the standard deviations. In the middle ball velocity group, you have pelvic turns ranging from 30.1 degrees all the way up to 64.9 degrees within one standard deviation of the mean. That is to say 68.2% of the population is in this range. That still leaves 31.8% of the population outside of this already large 30 degree range. To say that most golfers turn their pelvis in the 40-50 degree range in light of this data is just false. This is why I don't buy your its all about the shoulder turn argument. You still have to discuss the paired hip turn along with the shoulder turn for it to represent anything. Furthermore, if your argument was true that all hip turns were basically the same and the pelvic-torso separation is then a function of mostly the shoulder turn then you would not get a correlation for ball speed and torso-pelvic separation but a low insignificant correlation for upper torso rotation. They would both be correlated with balls speed, at least moderately. The fact that upper torso is not correlated with ball speed shows that you have to take the two together to correlate to ball speed, and the upper torso rotation can not be discussed alone. These "real life" arguments of yours just don't hold any water when compared to the data.

I find it odd that for someone demanding scientific evidence you keep invoking your "common sense" arguments. You keep wanting to give me a lesson about p values but don't even use means and standard deviations correctly to describe the populations.

[Veritas]

I also must say that I can not stand to continue to discuss the x-factor much more. I think I'm going to have to call it quits on this topic as I'm not sure we are ever going to get any farther in this discussion until more research is conducted.

[hoganfan924]

Well stated again Rdb..,

How's this for a "common sense" explanation of "stretch enduced force enhancement" (which to my understanding is not McLean's primary point about the importance of X-factor):

If you are trying to perform any athletic motion, e.g. jump as high as you can, throw a ball as far as you can, how would you most optimally do so to achieve maximum speed?

Ans. You "load up" and stretch the muscles which must be engaged in then contracting and shortening to produce the desired motion - for jumping highest you would [b]rapidly[/b] squat down and [b]rapidly change directions [/b]with no pause at the bottom. I may be incorrect, but have read that this induces the myotatic reflex which either: increases the number of muscle fibers engaged in the contraction or increases the speed of muscle contraction or stores more "spring" energy in the elongated muscle or possibly all three. I would be very interested if Rdb (or anyone else that has specific knowledge in this field) could enlighten us further as to which of these mechanisms are present in the stretch, load, unload cycle of muscular contraction.

BTW, as usual Jeffmann, very clever of you to shift the debate into a completely different realm of "stretch enduced force enhancement" when no such discussion is present in the McLean X-factor article. Another ruse no doubt to deflect the discussion away from your original misguided opinion about the validity of X-factor. Of cource, I've come to expect this so it's certainly no surprise.

[hoganfan924]

Just did a youtube search and found this from Shawn Clement: [url="http://www.youtube.com/watch?v=R8RJ-_gyK1Y&feature=related"]http://www.youtube.com/watch?v=R8RJ-_gyK1Y...feature=related[/url]

Excellent discussion of "X-factor Stretch," that he posted well before McLean came out with his new research. I'm very much in agreement with most of his major points although I'm not thrilled about his golf swing.

[Veritas]

HF,

I only have a little bit of knowledge on the myotatic reflix and really don't have much insight into its involvement in the golf swing. Here is a medical physiology book that discusses the response and what it is.

[url="http://books.google.com/books?id=PTL2IbxeIOUC&pg=PA96&lpg=PA96&dq=what+is+myotatic+response&source=web&ots=6AsjB7F-zi&sig=f2dOsyTV_P0vNVR72kzkrHuwfGo"]http://books.google.com/books?id=PTL2IbxeI...NVR72kzkrHuwfGo[/url]

I think if I had to postulate how this would help with the golf swing I would be fairly certain that it would not have anything to do with with energy storage. The reason why I say this is because it is a neuron signaling response causing muscle fibers to be fired and while the response is activated by stretch in the muscle, the actual response is a firing of the muscle and not a further stretch of the muscle. I think if it does have an effect it is going to be in how many muscle fibers are engaged. However, this is all just speculation and I don't have anything to back up what I just said. I don't know if this helps you at all.

[Golfchicago]

[quote name='hoganfan924' post='825690' date='Dec 15 2007, 05:20 PM']Just did a youtube search and found this from Shawn Clement: [url="http://www.youtube.com/watch?v=R8RJ-_gyK1Y&feature=related"]http://www.youtube.com/watch?v=R8RJ-_gyK1Y...feature=related[/url]

Excellent discussion of "X-factor Stretch," that he posted well before McLean came out with his new research. I'm very much in agreement with most of his major points although I'm not thrilled about his golf swing.[/quote]

HF
Interesting reference, I especially like his Hogan power drill video. Shawn's release in his swing looks odd though.

[JeffMann]

Robby,

My comments are interspersed between your previous comments.

Jeff.




I stated "Now to the data and Jeff's theory. First, they showed that there is a large and significant correlation (correlation = .54, p=.001) between Torso-pelvic separation and ball speed. This correlation confirms without a doubt that ball speed is correlated to pelvic-torso separation/xfactor and should not be argued. However, correlations don't mean causation, only that they are somehow related."
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You state that this correlation [b]confirms without a doubt[/b] that ball speed is correlated to the X-factor. I think that's junk science!!! A correlation coefficient of 0.54 is not much better than tossing a coin. That's a [b]moderately weak[/b] correlation value. The purpose of performing a correlation coefficient analysis is to search for causal links. The researchers couldn't find any strong correlations in their study when studying simple relationships (between a single independent variable and a single dependent variable), which is why they wrote that they[b] couldn't[/b] even prove that torso-pelvic separation was causally linked to increased ball velocity. I think that the researchers were scientifically naive in trying to establish a causal link via simple correlation coefficients - they should have studied multiple interactions.
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I don't claim a cause for the ball speed from their data. Just read above. I state correlation does not mean causation. My talk about torso/hip separation was meant to be postulating that the mechanism could be the extension muscle energy storage. I do not invoke any of the data that they present in this part of my discussion. I present the introduction where they provide references to studies that have shown evidence to this mechanism's possibility. Strong evidence that this mechanism is very possible in this system. I think your inability to accept this as a possible and likely significant contributor shows your own bias.
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It is reasonable to postulate a mechanism why increased torso-pelvic separation may cause increased ball velocity. However, you then state that previous studies have shown strong evidence. Strong evidence !!! That's not real science!!! You have not even read those studies. How do you know that they provide strong evidence?

Of course, I have an inherent bias. Common sense dictates that if a person is capable of contracting his torso muscles eccentrically during the downswing, that it is likely that he can generate more force per unit time if the muscles can contract a greater length (by extending the length of the muscles via increased torso-pelvic separation). That is not the issue that needs to be debated. You even accept that fact, and have the same inherent bias. The real question is whether stretch-induced force enhancement of muscle contraction plays a significant role - by significant, I mean at least a 10% increase in ball velocity values due to that factor. If you believe that fact, then the onus is on you to provide scientific proof. Quoting papers that you haven't even read is not scientific proof - it's junk science!
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Second, your inability to see how we could both be right is just evidence that you didn't read or interpret correctly what I was talking about. I wasn't saying our interpretation of the paper was the same but that both our theories about how the x-factor could be correlated to ball speed could both be factors. We can both be right because it is a human system that has many factors working at the same time. It is very easy to envision a system that is both benefiting from the energy transfer of the lower torso pulling on the upper torso, as well as enhanced force production from muscle/tendon energy storage. Your lower body transfers the load to the upper torso causing acceleration of the upper torso while the increased force production from the muscles in the extended state further accelerate the upper torso as well. Both postulated mechanisms occurring at the same time.
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I agree that both postulated mechanisms occur at the same time, but the real question is whether stretch-induced force enhancement of muscle contraction plays a substantial role. I doubt it!
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You state, "To accomplish that goal, you would have to demonstrate how you can scientifically differentiate between two factors that are at play during increased eccentric loading of torso muscles secondary to a large X-factor - i) stretch-induced force enhancement of muscle contraction (which is passive); and ii) increased active muscular contractile force due to the increased muscle elongation that accompanies increased eccentric loading (which is active)." I don't need to differentiate between the two. I am postulating both of these effects, as they are both a result of increased stretch within the muscles. I take both the active and passive increases to be what I am arguing for. I do recognize that more research needs to be done to further show this in the golf swing and I hope they conduct these studies. However, I have given scientific proof of a possible mechanism while you still rely on your "real life" examples to support your theory. If you have the proof I would love to see it.
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You state that you have provided scientific proof. What!!! How do you have the audacity to state that you have provided scientific proof. Quoting papers that you haven't read doesn't constitute scientific proof. You are demeaning the true meaning of scientific proof - which is an experimental test that is rigorously designed to assess a scientific hypothesis, and where there is a minimum of confounding variables (other causal factors that produce the same effect) in the study. Can you refer me to any such study? I don't think that I have to prove that increasing the length of a torso muscle eccentrically will result in a greater force of contraction per unit time if the muscle shortens by that increased length per unit time. It's a well established scientific fact that is not scientifically controversial. What is controversial is the stretch-induced force enhancement theory that underlies the belief in the relevance of the static X-factor.
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You state..."The simple shoulder turn without separation from the from the pelvis will lead to a poor transfer of power to the upper torso from the lower body rotation due to the lack of tension in the muscles." I simply cannot understand the significance of this statement." You support this argument by saying that most golfers turn their hips around 40-50 degrees and in your previous argument you supported this with the means in the data between the HBV, MBV, and LBV groups. This however is a misuse of what the means represent. All that says is that the "average" golfer between the groups is around the same. To truly look at the population and how golfers turn the pelvis you have to look at the standard deviations. In the middle ball velocity group, you have pelvic turns ranging from 30.1 degrees all the way up to 64.9 degrees within one standard deviation of the mean. That is to say 68.2% of the population is in this range. That still leaves 31.8% of the population outside of this already large 30 degree range. To say that most golfers turn their pelvis in the 40-50 degree range in light of this data is just false. This is why I don't buy your its all about the shoulder turn argument. You still have to discuss the paired hip turn along with the shoulder turn for it to represent anything. Furthermore, if your argument was true that all hip turns were basically the same and the pelvic-torso separation is then a function of mostly the shoulder turn then you would not get a correlation for ball speed and torso-pelvic separation but a low insignificant correlation for upper torso rotation. They would both be correlated with balls speed, at least moderately. The fact that upper torso is not correlated with ball speed shows that you have to take the two together to correlate to ball speed, and the upper torso rotation can not be discussed alone. These "real life" arguments of yours just don't hold any water when compared to the data.
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You state that I need to address the fact that the point estimate values only represent the "average value" and that there is variance between subjects. Of course, there is variance, but when commenting on a research study, one can only talk about the point estimate values as being representative of the "average" subject. The purpose of studying the variance is to determine whether the study can produce scientifically conclusive results with a great deal of confidence. A scientifically conclusive result is only present when the point estimate result has a narrow 95% confidence interval. The researchers didn't publish the 95% CI results for their point estimate results, and that makes it impossible to judge the study's results in terms of confidence in the quality of its scientific conclusion. If you read those three posts that I supplied on the p-value, then you may understand why I only believe in 95% CI values and not p-values.
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I find it odd that for someone demanding scientific evidence you keep invoking your "common sense" arguments. You keep wanting to give me a lesson about p values but don't even use means and standard deviations correctly to describe the populations.
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What!!!

[Points]

Once again, Jeff is on the attack but provides no scientific proof. As far this discussion goes, the onus is on you to provide new information which disproves the X factor which you have yet to do. Robby provides calculations and you provide none other than "common sense." As best I can tell, the only one not contributing to this discussion is you Jeff. I would absolutley love to see why the X factor is "junk science." Do the research and provide the results.

[JeffMann]

Points

You don't understand science. I don't have to disprove the validity of a [b]new[/b] hypothesis (X-factor hypothesis). The [b]new [/b]hypothesis has to prove its scientific validity.

It is well known to even beginner golfers that one has to turn the shoulders more than the hips in the backswing. They don't require scientific proof to know that they can hit the ball further if they turn their shoulders more than their hips. Most beginner golfers are taught to rotate their hips a moderate amount and their shoulders a greater amount. Even old-timers, like golfers in the Harry Vardon or Bobby Jones era, knew that basic fact. When McLean first introduced the idea of the X-factor, he was not simply stating that one should turn one's shoulders more than the hips. He introduced the idea of coiling/stretching the upper body against the resistance of the lower body as a potential source of [b]added[/b] power, and that started a fad for restraining the hip turn in the backswing so as to maximise torso-pelvic separation. The idea of maximising torso-pelvic separation is intimately linked to the idea of stretching the upper torso against the resistance offered by a more restrained lower torso turn. Whether this stretching phenomenon due to increased torso-pelvic separation [b]significantly[/b] increases swing power needs scientific validation. That recent study by Myers could [b]not [/b]even establish a causal link between increased torso-pelvic separation and increased ball velocity, and it was certainly [b]not[/b] capable of studying the biomechanical mechanisms that would be operant if increased torso-pelvic separation [b]could [/b]be shown to increase ball velocity.

Jeff.

[Points]

Seeing as how scientits have been studying the X factor for the past fifteen years and none to my knowledge have disproven it, I question whether it is that it is still considered a hypothesis. Please show through other studies, rather than your opinion, that the X factor being disproven.

[JeffMann]

Points - you wrote-: "Seeing as how scientits have been studying the X factor for the past fifteen years and none to my knowledge have disproven it, I question whether it is that it is still considered a hypothesis. Please show through other studies, rather than your opinion, that the X factor being disproven."

Your lack of knowledge as to how science works is astonishing. Science starts with a hypothesis which has to be tested via a scientific experiment. If the hypothesis is proven, then it becomes the "best" explanatory theory ("best" is defined in scientific terms as having a low falsifiability factor, and not a high verifiability factor). If a scientist proposes a scientific hypothesis, other scientists don't bother to try and falsify that hypothesis via further scientific testing, unless the original hypothesis has passed preliminary tests suggesting that the hypothesis has substantial merit.

Take a simple example. If a scientist has a hypothesis that increased torso-pelvic separation in a golf swing increases swing power, he will first have to study that relationship by performing a simple observational study - like the study performed by Myers. That study showed only a 0.54 correlation between increased torso-pelvic separation and increased ball velocity. The strength of that correlation value of 0.54 needs further analysis and one tests the strength of a correlation r by looking at r squared. If one squares an r of 0.54, then it comes out to a figure of 25%, which means that there is only a loose link between the independent variable (increased torso-pelvic separation) and the dependent variable (increased ball velocity). With such a poor correlation, and such a weak hypothesis, why should other scientiits even bother trying to disprove (falsify) that hypothesis - which doesn't even have enough scientific merit to warrant intensive scientific challenges? Scientists are usually only interested in challenging a scientific hypothesis if [b]initia[/b]l scientific testing shows that the hypothesis is likely to have a low chance of being falsified by further experimentation. The X-factor hypothesis [b]hasn't [/b]even passed the [b]first [/b]hurdle of establishing itself as a legitimate scientific theory that [b]may [/b]have a[b] low[/b] falsifiability index.


Jeff.

p.s. Here are a few links to help people understand what what correlation means in statistical terms.

[url="http://www.graphpad.com/articles/interpret/corl_n_linear_reg/correlation.htm"]Prism Guide[/url]

[url="http://janda.org/c10/Lectures/topic04/L23-InterpretingR.htm"]Interpreting r[/url]

[url="http://sahs.utmb.edu/pellinore/intro_to_research/wad/correlat.htm"]Interpreting statistics[/url]

[scores]

Just Naturally swing'ing the club with out reading all this and you will have a better X factor. The biggest restriction is the mind!!!!

I think if you try and restict your hips you will hurt your back... I don't care what anyone saids I have lived it and if a person is athletic and strong the force or power of your own down swing and then trying restict u r hips..You will have a ruptured disc..

What thy tell you to do is stretch to prevent it from happening well whats wrong with stretching everything out of the way ...when you swing??? why not

This is how close DD and SF really are because I got this thinking right of of DD's website when He is giving a Driver lesson to one of his students..He talks clearly on no restiction of the lower body!!! strech that tail end out... I can see this in a lot of players that swing left Hunter Mahan good example

[jaridyard]

Jeff,

Would there be any other reasons beside Myers inconclusive paper that might stop research being undertaken? How would you suggest the testing would take place, furthermore what would be your Hypothesis and Null Hypothesis.
Just interested as I have access to a great facility who might be interested.

[caryk]

Maybe Doc and this guy (Arthur De Vany) should partner up. Would be an interesting discussion.

Check out his article (June 20, 2007) on the golf swing and what he has to say about it ...

[url="http://www.arthurdevany.com/sports/"]http://www.arthurdevany.com/sports/[/url]

[Veritas]

lolololololol. incredible. Gloves off.

Jeff. You have no actual understanding of what a correlation value represents or how to apply it in a biological realm. A correlation coefficient of .54, in fields such as biology and social sciences where there are many variables, is large. Cohen (1988) is where I got these ranges from, which was provided to me in a clinical biostatistics course. Also, I would like to point out that at first the author and you said it was a moderate value and now you are calling it "moderately weak". Your definitions seem to change and gravitate further and further to support your arguments. Finally, on this point, flipping a coin has nothing to do with a correlation statistic and provides nothing to this discussion.

You say this: "you state that this correlation confirms without a doubt that ball speed is correlated to the X-factor. I think that's junk science!!!" Do you even realize what you just said. You basically called correlation statistics junk science. In fact if you want to get on to me for anything you should get onto me for making a completely trivial claim there. Of course, if a correlation statistic shows a significant correlation then there is of course, a correlation. Whether the correlation is weak or strong, it is still a correlation. But you called that junk science. I will have to let scientists around the world know that correlation stats are junk science. You should probably add that to your essay on Jeffman's rules of science. I'm not sure if this is a case of gross error in your stat understanding or your continued reading comprehension problem.

"The purpose of performing a correlation coefficient analysis is to search for causal links. The researchers couldn't find any strong correlations in their study when studying simple relationships (between a single independent variable and a single dependent variable), which is why they wrote that they couldn't even prove that torso-pelvic separation was causally linked to increased ball velocity." WRONG. The purpose for doing correlations is to find [b]possible[/b] causal links. The correlation stat shows there is a possible causal link if there is a correlation. The correlation coefficient never proves a causal link. This is why they can't confirm causal link between the two, not because the correlation coefficient was too small. This is another example of your complete misunderstanding of correlations and even what the author is saying. Are you even reading anything that closely or do you just have a problem with reading comprehension?

You state:
"You state that you have provided scientific proof. What!!! How do you have the audacity to state that you have provided scientific proof. Quoting papers that you haven't read doesn't constitute scientific proof. You are demeaning the true meaning of scientific proof - which is an experimental test that is rigorously designed to assess a scientific hypothesis, and where there is a minimum of confounding variables (other causal factors that produce the same effect) in the study. Can you refer me to any such study? I don't think that I have to prove that increasing the length of a torso muscle eccentrically will result in a greater force of contraction per unit time if the muscle shortens by that increased length per unit time. It's a well established scientific fact that is not scientifically controversial. What is controversial is the stretch-induced force enhancement theory that underlies the belief in the relevance of the static X-factor."

Yes I provided scientific proof of a possible mechanism. I provided references for papers that show that stretch induced increase in work output occurs in muscles. Did I prove that it happens in the golf swing? no. I didn't claim that I did. Read Read Read. And Jeffman, you might want to make sure someone hasn't read any of the papers before you say they haven't. Because I for sure did pull up and read the paper EFFECTS OF PRESTRETCH AT THE ONSET OF
STIMULATION ON MECHANICAL WORK OUTPUT OF RAT
MEDIAL GASTROCNEMIUS MUSCLE-TENDON COMPLEX
BY G. J. C. ETTEMA, P. A. HUIJING, G. J. VAN INGEN SCHENAU AND
A. DEHAAN
Did I read every single one, no. I don't have time for that but I did my homework on the paper I thought most relevant to the possibility of stretch induced increased in work output. Here is another question, did you read any of the papers I referenced?


"You state that I need to address the fact that the point estimate values only represent the "average value" and that there is variance between subjects. Of course, there is variance, but when commenting on a research study, one can only talk about the point estimate values as being representative of the "average" subject. The purpose of studying the variance is to determine whether the study can produce scientifically conclusive results with a great deal of confidence. A scientifically conclusive result is only present when the point estimate result has a narrow 95% confidence interval. The researchers didn't publish the 95% CI results for their point estimate results, and that makes it impossible to judge the study's results in terms of confidence in the quality of its scientific conclusion. If you read those three posts that I supplied on the p-value, then you may understand why I only believe in 95% CI values and not p-values."

The above argument doesn't have anything to do with what I was saying. You basically tried to defend yourself by providing an explanation of something I was not even addressing. Here it comes again, READ. One minor point though is that standard deviation and variance are not the same thing even though they are related. And the purpose of studying standard deviations is to fully define and describe the population, not just to see if you can determine whether you can make scientifically significant conclusions. My analysis of your ridiculous claim that people only range in hip turn from 40-50 degrees is dead on.

"I don't think that I have to prove that increasing the length of a torso muscle eccentrically will result in a greater force of contraction per unit time if the muscle shortens by that increased length per unit time. It's a well established scientific fact that is not scientifically controversial. What is controversial is the stretch-induced force enhancement theory that underlies the belief in the relevance of the static X-factor."

Once again not what you were arguing for before. You were talking about pelvic rotation velocity and shoulder turns. I don't disagree with what you just said but it is irrelevant to what I asked you to prove. You keep changing what you are trying to defend. You jump around so much in what you say you are arguing for its impossible to actually have a productive argument with you. Also, here is where your double standard comes out. Even if we were arguing about this and it is well established, then it sure as heck should be pretty easy to provide me some papers on it. I have been busting my butt trying to provide you with papers and scientific research on these topics. You have provided me with nothing.

You state:
"I find it odd that for someone demanding scientific evidence you keep invoking your "common sense" arguments. You keep wanting to give me a lesson about p values but don't even use means and standard deviations correctly to describe the populations.
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What!!!"
This is me telling you that you don't know what you are talking about. I thought that was clear.

Jeff, you have showed a continued lack of scientific understanding from the beginning of this argument from denying tendon stores energy to your statistical "knowledge". You stated tendon was not elastic and wasn't designed to store energy and once I proved this incorrect, you changed your argument to it not being significant in the golf swing. This is a prime example of how you argue and refuse to be wrong. Your arguments change and float so much that it is nearly impossible to keep track of what is even going on sometimes in these discussions. I will not continue this chain of discussions with you one post further. Say whatever you want, I will not respond. Our communications are no longer useful to anyone reading this board and I will not continue with it.

[JeffMann]

Jarid

You pose an important question. How would one test whether a static X-factor increases swing power? To test a scientific hypothesis, one first needs to accurately define the hypothesis.

My first question is how does one really define a static X-factor? Prior to McLean coming up with his idea, golfers knew that a full/complete swing produced more swing power than an incomplete/three-quarter swing. What's the difference between a full swing and an incomplete swing? Surely it's the degree of torso-pelvic separation in the sense that a full swing primarily involves a greater shoulder turn with very little change in the degree of hip turn, thus maximising the degree of torso-pelvic separation. For decades/centuries prior to McLean's idea of the X-factor, golfers instinctively knew that a full swing would allow them to generate greater swing power than an incomplete swing. Now, if McLean came along and stated that he had a new swing idea - called the X-factor - which would increase swing power, and it simply involved maximising torso-pelvic separation so as to ensure a full swing, people would have laughed because they already knew that they could hit the ball further by ensuring that their swing was complete/full. Therefore, Mclean semingly re-phrased it by saying that maximising torso-pelvic separation involves a process whereby the upper body is torqued against the resistance of the lower body in order to create stretch-coiling during the backswing, and that this phenomenon would supply [b]additional[/b] power through a mechanism of passive uncoiling (elastic stretch release) during the downswing. In other words, his hypothesis would be that a golfer could obtain [b]additional[/b] swing power through a coiling/uncoiling or a stretch/unstretch biomechanical process, that is unrelated to the swing power normally generated by active contraction of the torso muscles, which are more elongated during a complete swing.

Is that how you understand the X-factor, or do you feel that I have misrepresented McLean's idea of the static X-factor?

[JeffMann]

Robby - Don't apologize for taking your gloves off. Being frank and fully expressive in support of your opinions is welcomed. That's what this forum is all about - spirited discussion where each forum member argues passionately in favor of his opinions.

One of the problems inherent in this type of discussion is misinterpretation and/or misrepresentation of another forum member's arguments. I don't believe that it is intentional, but it does oblige the misunderstood/misrepresented forum member to make an additional effort to be better understood. I am therefore re-stating certain points where I think that I have been misunderstood/misrepresented.

-------------------------------------------------------

You stated-: "You say this: "you state that this correlation confirms without a doubt that ball speed is correlated to the X-factor. I think that's junk science!!!" Do you even realize what you just said. You basically called correlation statistics junk science."

You have misunderstood what I stated. I stated that junk science is implying that a moderately strong correlation (r value of 0.54) implies a [b]significantly strong[/b] correlation value. To test the strength of a correlation, one needs to square the correlation (0.54 squared) to determine the coefficient of determination. That comes out to a coefficient of determination value of 0.25 -- see the graph in this [url="http://janda.org/c10/Lectures/topic04/L23-InterpretingR.htm"]link[/url] to determine how I calculated the coefficient of determination value of 0.25.

I regard that 0.25 value to be very low, and [b]not [/b]evidence of a strong correlation. A strong correlation doesn't imply causality, but a strong correlation must be present as a first step to eventually establish causality. Because this study showed such a low coefficient of determination value of 25% (0.25), I regard the [b]claim[/b] that increased torso-pelvis separation causes increased ball velocity to be junk science - because the correlation is i[b]nsufficiently strong[/b] to support the idea of causality, and not because I don't believe in correlation statistics.

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You stated-: " WRONG. The purpose for doing correlations is to find possible causal links. The correlation stat shows there is a possible causal link if there is a correlation. The correlation coefficient never proves a causal link. This is why they can't confirm causal link between the two, not because the correlation coefficient was too small. This is another example of your complete misunderstanding of correlations and even what the author is saying."

We agree that a correlation never proves a casual link. However, I think that you are wrong to state that "the correlation stat shows there is a possible causal link if there is correlation" because that statement is only correct if you state "[b]significantly strong[/b] correlation". As I stated in the answer above, one needs to determine the coefficient of determination to test the strength of a correlation, and a value of 0.25 definitely doesn't represent a [b]sufficiently strong[/b] correlation to even entertain the idea of subsequently proving causality.

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You wrote-: "Yes I provided scientific proof of a possible mechanism. I provided references for papers that show that stretch induced increase in work output occurs in muscles."

We see the issue differently. You are referencing laboratory experiments on rat muscles. I don't dispute that stretching a muscle-tendon complex in a laboratory setting can produce [b]passive[/b] recoil forces when the muscle-tendon unit recoils during the release phase. You then have to demonstrate how this knowledge allows you to compute [b]how much[/b] passive recoil of eccentrically loaded torso muscle/tendons adds power to the force generated by active muscle contraction of those [b]same[/b] muscle/tendon units during the downswing. I will comment further when I see your computations and their underlying assumptions.

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You wrote-: "One minor point though is that standard deviation and variance are not the same thing even though they are related. And the purpose of studying standard deviations is to fully define and describe the population, not just to see if you can determine whether you can make scientifically significant conclusions. My analysis of your ridiculous claim that people only range in hip turn from 40-50 degrees is dead on."

You misunderstood me. When I stated that the average golfer has a hip turn of 40-50 degrees, I am referring to the "average" golfer. I am not talking about statistical outliers. When evalauating the scientific legitimacy of a research study, the importance of these outliers is established by publishing statistics relating to the variance, which is statistically linked to the concept of standard deviation. In scientific research papers, it is traditional to use the 95% confidence interval values, and that represents two standard deviations.

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You write-: "I have been busting my butt trying to provide you with papers and scientific research on these topics. You have provided me with nothing."

Please be more precise as to what point(s) I need to scientifically defend (scientifically validate).

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You write-: " I will not continue this chain of discussions with you one post further. Say whatever you want, I will not respond. Our communications are no longer useful to anyone reading this board and I will not continue with it."

You are free to discontinue posting any more comments, but I think that it is presumptuous of you to say that our communications are not useful to [b]anyone[/b] reading this board (thread).

Jeff.

[hoganfan924]

More fuel to the fire (and, no Jeffmann, I'm not interesting in any further "debate"). Hope this will be my last post in this abortion of a thread. (sorry if that offends anyone)

In the recent "no backswing golfswing article" in Golf magazine (which was a complete rip-off of something Leadbetter did a few years earlier) the authors claim that with "no backswing" golfers were hitting the ball more solidly and with less dispersion, but, [b]shorter[/b] according to this bar chart (considerably shorter for very good players). Evidence of stretch enduced force increase or perhaps the myotatic reflex? I think so!:
[attachment=199020:no_backswing.jpg]

Here's the article: [url="http://www.golf.com/golf/instruction/article/preview/0,28136,1652866-2,00.html"]http://www.golf.com/golf/instruction/artic...52866-2,00.html[/url]

To add some additional anectodal evidence, besides the fact that most very good golfers feel a stretch and the effortless distance that it produces (as I believe is supported by the chart above), here's a direct quote from Peggy Kirk Bell from the July GD, pg. 166 "My turn", a pretty fine golfer herself and pretty knowledgable about the golf swing:

Talking about Bade Diedrickson Zaharias, arguably the greatest female athlete of all time: "Babe hit the ball a ton. I asked her how she got such amazing distance for being only 5' 7". Using her right hand, she reached over her left shoulder and patted herself just above her left shoulder blade. "I take it away with this muscle on the backswing, then I hit it." She said. That muscle in the upper left side of you back is a key one. If you can [b]stretch it out like a spring [/b]going back, you'll get incredible speed coming down, and a lot more distance."

Interestingly, Slicefixer stressed to me a month before that article came out "you've got to stretch the left lat muscle in the backswing!"

That, and everything else that's been discussed in this thread by me, Rdb.., Points, et. al. is enough evidence for me to use this concept to improve my own golf game.

To say that McLean's conclusion that static X-factor was obvious and known to most golfers isn't completely correct either. It at one time was a hypothesis that others had mentioned prior but that he was the first to measure and quantify.

I once read that all great new ideas go through three phases of acceptance:
1. They are dismissed as folly (Jeffmann's first post)
2. They are violently opposed (Subsequent posts)
3. They are accepted as the self-evident truth (could he finally be coming around?)

Carry on Doc, and keep shifting the discussion to things Jim McLean didn't claim so you don't have to admit you were wrong.

[slicefixer]

[quote name='caryk' post='826584' date='Dec 16 2007, 03:18 PM']Maybe Doc and this guy (Arthur De Vany) should partner up. Would be an interesting discussion.

Check out his article (June 20, 2007) on the golf swing and what he has to say about it ...

[url="http://www.arthurdevany.com/sports/"]http://www.arthurdevany.com/sports/[/url][/quote]


Art De Vany....Art Van Delay.......hmmm...... (dont' know what it really means, I just LUV Seinfeld...hehehe)

[jeffy]

Had three [b]GREAT[/b] days with Dana Dahlquist and Mike McNary, while some folks just endlessly argued with that contrary SOB Uncle Jeff. Go figure.