McLeans' X factor

[Points]

Jeff,

From the beginning, I stated that you have done little to no homework into the ideas regarding the X factor. The even sadder thing about this entire thread is that you didn't even take the time to actually read what I has posted. Instead, as you have done before, you took a small quote to bolster your own position. Read my posts, do the research, provide facts as to what is wrong with the X factor.

[Points]

[quote name='hayam' post='823637' date='Dec 13 2007, 08:49 PM'][quote name='christhebigsmokemoss' post='823242' date='Dec 13 2007, 04:05 PM']This might be the best way to increase power but it is also the best way to increase injury![/quote]


Exactly.
These thoughts injected to inflexible beings spells Injury, and bad overswings.

In theory I kinda agree with Mclean. I think that his theory is correct. The more flexible the golfer , the more energy he can create.. THOUGH, He did not explain there are OTHER things beside that which is responsible for substantial power for any golfers.
[/quote]

Once again, completely wrong as it pertains to the X factor. To think a 60 year will have the same X factor as a 20 year old PGA tour stud is simply ridiculous. Jim states in his book that as people age the differential is less and the amount of hip turn will increase. Says so very clearly in his book. The X factor is not and has never been about limiting you hip turn and maximizing your shoulder turn.

[hayam]

Get it Points.

Alot of people. including me at one point. TRY to create the X - factor artificially. Disaster.

X-factor cannott be created artificially, its highly dependent on the flexibility of the players. Its a Study materials.. not instructional material. Seldom people read the "fine prints " LOL.. Same case with S&T, and many other "preview" instructional materials in magazines.

[JeffMann]

HF

I am definitely retracting certain points that I have made about the X-factor. I didn't originally realise that different people understand the X-factor as meaning different things. I changed my thinking on the X-factor in the past year, not because I didn't believe that a large difference in the degree of shoulder-versus-hip turn during the backswing was biomechanically significant, but because I didn't accept the theoretical explanation that usually accompanied the McLean study's observations. The theoretical explanation talked about coiling and uncoiling of the body based on stretching of torso muscles/tendons. I didn't think that this theoretical explanation was biologically plausible, and that's why I changed my thinking about the concept of the X-factor.

However, when re-reading the posts of Points, he merely stated that a large shoulder-hip turn differential was equivalent to a large X-factor, and it would seem that he believes that the concept of the X-factor is merely reflective of a large shoulder-hip turn differential - without having to postulate an explanatory reason as to why the large differential causes an increase in clubhead speed and driving distance. In that sense, I agree with him. It is obvious that if a golfer has an average hip turn of 45 degrees, but has an additional 10-20 degrees of shoulder rotation, that this could translate into faster shoulder turn speeds and therefore a faster clubhead speed. It is also my experience that experienced golfers who can turn their shoulders 100-110 degrees, like Tiger Woods, also have the ability to turn their hips at faster than normal speeds, which will also increase clubhead speed. The ability to increase hip turn speed is unrelated to the concept of the X-factor, but I think that pro golfers who have an increased shoulder turn usually also have the ability to turn their lower torso faster during the downswing. The net result of these two effects is faster clubhead speed and greater ball flight distance.

Jeff.

[pbh]

[quote name='rdbivyleagun' post='823397' date='Dec 13 2007, 11:58 PM'][quote name='JeffMann' post='823216' date='Dec 13 2007, 03:50 PM']Robby - if you theorised that a strong golfer could store 1-5% of his potential downswing swing power by stretching torso muscles/tendons during the backswing, I wouldn't bother to question the scientific legitimacy of that figure. However, I would seriously question the legitimacy of any postulated value above 5% and I would probably request scientific proof.

Jeff.[/quote]

Jeff,

Ok lets go with 1-5% then. So lets consider one golfer and say that if he swings with a small x-factor and stores only 1% of energy in the tendons and swings at 100 mph but also can swing and store 5% energy in the tendons with a large x-factor and swing at 103.125 mph as a result of the increased energy being stored (everything else being equal). Then using the generalized calculation of swing speed X 2.450 = carry distance, the swing with a larger x-factor will carry 252.66 while the lower x-factor will give you a carry distance of 245. Thats a difference in almost 8 yards of carry. I find that to be quite significant considering we are only talking about the elastic storage of energy and nothing else. I know I wouldn't mind picking up 8 yards.
[/quote]

If you can store 4% extra energy, it does not neccessarly mean that it directly translates into 4% extra kinetic energy of the club head. But if it does the kinetick energy is W=(mv^2)/2 which means 4% energy increase gives 1% speed increase. Your speed increase is then 1mph. That means that the maximum distance increase is 2.45 yards.

[Veritas]

[quote name='pbh' post='824016' date='Dec 14 2007, 04:49 AM'][quote name='rdbivyleagun' post='823397' date='Dec 13 2007, 11:58 PM'][quote name='JeffMann' post='823216' date='Dec 13 2007, 03:50 PM']Robby - if you theorised that a strong golfer could store 1-5% of his potential downswing swing power by stretching torso muscles/tendons during the backswing, I wouldn't bother to question the scientific legitimacy of that figure. However, I would seriously question the legitimacy of any postulated value above 5% and I would probably request scientific proof.

Jeff.[/quote]

Jeff,

Ok lets go with 1-5% then. So lets consider one golfer and say that if he swings with a small x-factor and stores only 1% of energy in the tendons and swings at 100 mph but also can swing and store 5% energy in the tendons with a large x-factor and swing at 103.125 mph as a result of the increased energy being stored (everything else being equal). Then using the generalized calculation of swing speed X 2.450 = carry distance, the swing with a larger x-factor will carry 252.66 while the lower x-factor will give you a carry distance of 245. Thats a difference in almost 8 yards of carry. I find that to be quite significant considering we are only talking about the elastic storage of energy and nothing else. I know I wouldn't mind picking up 8 yards.
[/quote]

If you can store 4% extra energy, it does not neccessarly mean that it directly translates into 4% extra kinetic energy of the club head. But if it does the kinetick energy is W=(mv^2)/2 which means 4% energy increase gives 1% speed increase. Your speed increase is then 1mph. That means that the maximum distance increase is 2.45 yards.
[/quote]


Yes, you are correct pbh and I will definitely admit the mistake, I was trying to do a quick calculation because my wife wanted me off golfwrx to hang out with her and I should have used rotational kinetic energy equation here instead of just assuming an increase in kinetic energy by the same percentage. Good catch. Sorry, my wife wanted me off the message board so I tried to do something quickly here.

As to the storage of energy. If you look at my previous arguments I was not trying to talk about % of storage of energy but the percentage actually returned. I choose to just go with energy stored because the return of energy in tendon is actually quite high. The hysteresis loop that occurs in tendon shows that you will lose only 5-10% of the energy stored in the tendon to heat. So I just choose to say it was the amount stored but that is not technically not correct and I should have said it was the amount being returned.

One thing I love about doing these golf calculations is it really rejogs the memory on your intro level physics. It's amazing how much of this you don't deal with that often even doing a PhD in biomechanics.

[Veritas]

[quote name='rdbivyleagun' post='824084' date='Dec 14 2007, 08:17 AM'][quote name='pbh' post='824016' date='Dec 14 2007, 04:49 AM'][quote name='rdbivyleagun' post='823397' date='Dec 13 2007, 11:58 PM'][quote name='JeffMann' post='823216' date='Dec 13 2007, 03:50 PM']Robby - if you theorised that a strong golfer could store 1-5% of his potential downswing swing power by stretching torso muscles/tendons during the backswing, I wouldn't bother to question the scientific legitimacy of that figure. However, I would seriously question the legitimacy of any postulated value above 5% and I would probably request scientific proof.

Jeff.[/quote]

Jeff,

Ok lets go with 1-5% then. So lets consider one golfer and say that if he swings with a small x-factor and stores only 1% of energy in the tendons and swings at 100 mph but also can swing and store 5% energy in the tendons with a large x-factor and swing at 103.125 mph as a result of the increased energy being stored (everything else being equal). Then using the generalized calculation of swing speed X 2.450 = carry distance, the swing with a larger x-factor will carry 252.66 while the lower x-factor will give you a carry distance of 245. Thats a difference in almost 8 yards of carry. I find that to be quite significant considering we are only talking about the elastic storage of energy and nothing else. I know I wouldn't mind picking up 8 yards.
[/quote]

If you can store 4% extra energy, it does not neccessarly mean that it directly translates into 4% extra kinetic energy of the club head. But if it does the kinetick energy is W=(mv^2)/2 which means 4% energy increase gives 1% speed increase. Your speed increase is then 1mph. That means that the maximum distance increase is 2.45 yards.
[/quote]


Yes, you are correct pbh and I will definitely admit the mistake, I was trying to do a quick calculation because my wife wanted me off golfwrx to hang out with her and I should have used rotational kinetic energy equation here instead of just assuming an increase in kinetic energy by the same percentage. Good catch. Sorry, my wife wanted me off the message board so I tried to do something quickly here.

As to the storage of energy. If you look at my previous arguments I was not trying to talk about % of storage of energy but the percentage actually returned. I choose to just go with energy stored because the return of energy in tendon is actually quite high. The hysteresis loop that occurs in tendon shows that you will lose only 5-10% of the energy stored in the tendon to heat. So I just choose to say it was the amount stored but that is not technically not correct and I should have said it was the amount being returned.

One thing I love about doing these golf calculations is it really rejogs the memory on your intro level physics. It's amazing how much of this you don't deal with that often even doing a PhD in biomechanics.
[/quote]

So this inspired me to do a more rigorous calculation because even though pbh is correct that my calculations were not correct, the equation he suggests is not correct either. You need to use the rotational kinetic energy equation which would be RKE=.5*I*(angular velocity)^2 not the linear version. When doing this calculation using values obtained for moment of inertia of the human body in this situation you will get a difference in swing speeds of 101.54 mph versus 100.00 mph. This calculates out to be 3.77 yards of carry or about half of my original calculation. I still think this is interesting seeing how tendon was written off to have no effect at the beginning of this argument. I haven't done a calculation like that in years. Good times.

[hoganfan924]

Rdb..,

Good to see you putting that Biomechanics degree to good use!

One of my few regrets in life was not pursuing a Masters in Biomechanics. Keep up the good work. You're might well be the only guy on this board truly qualified to answer these questions. Interesting stuff you wrote about elephants and tendons! Would be interested to hear your view of the role of the myotatic reflex in the golfswing.

[Veritas]

wow, one thing that totally slipped my mind that I really think should enter the conversation is muscle force vectors. This is the idea that as one rotates into a greater x-factor, many of the muscles are going to not just stretch but also rotate and change the directions that they will impart their force. So, as a result, the muscles as you rotate will take on an orientation that will impart more of a rotational vector force instead of a vertical directional force. This would result in an increase in the rotational force the muscles can provide not by allowing more force to be generated by the muscle, but by allowing more of the force it would normally generate to be in the rotational direction. I don't know why this didn't hit me sooner, especially since my intervertebral disc research directly deals with this principle but with collagen fibrils and not muscle. And before Jeff asks which muscles are involved, I will simply say all muscles that can impart rotational force and cause this motion. Either you will increase your rotational vector for those muscles that would rotate in the desired direction or those muscle that oppose the direction of rotation you are going for will decrease in their rotational vector and ability to resist the rotation. Both are good for increased rotational forces in the desired direction.

[hoganfan924]

I think one of the biggest points of confusion in this entire thread has to do with "stretching" vs. muscle elongation. A muscle in the fully contracted [b]position[/b], can produce no motion and therefore no work or power. A muscle therefore has to be elongated before its contraction can produce motion. That's not "stretching" beyond a muscles normal limits as might happen when a joint is hyperexteded. It is not my contention that muscles are "overstretched" in a golfswing with large X-factor (although it's possible that there might be, I'm just not sure and can't think of specific muscles that I believe would be "overstretched"). Jeffmann's earlier example of the biceps muscle in the "normal" at-rest arm is a very poor one because the normal at rest arm has the biceps brachii and brachialis muscles almost fully elongated already. The counterpoint to the biceps example is the triceps. Try thowing a football with the arm lengthened at it's normal resting position (of course moving it overhead but still relatively straight) and tell me how you can achieve maximum throw distance or speed without bending the elbow considerably (around 90 degrees). You can't, because you aren't using the powerful triceps muscle without first bending at the elbow to get the triceps into a normal elongated position, not an "overstretched" one.

Nowhere in the McLean article do I see any inference that "overstretching" muscles and tendons is what causes an increase in clubhead speed for players with large X-factors, although I think that this [i]might[/i] be possible and should be pursued with further research.

[slicefixer]

..........as the true scientists enter the room it just keeps getting quieter.........and quieter........................and quieter........................................and quieter.........................................................................
.......................and quieter.........................................................................
................................................................................
......and quieter............................(hehehehe............VERY interesting discussion IMOP........best in awhile)

[JeffMann]

Robby

With your great knowledge of biomechanics, I look forward to reading your insights on the Myers paper that I sent you. I hope that you share you conclusions with this forum's members.

Consider my personal conclusion. I think that there are two ways to interpret the study's results. The one way is to conclude that a good golfer has a greater degree of shoulder-hip separation during the backswing and that promotes a faster clubhead speed (as would be predicted by the McLean theory), and that some of that speed is due to greater torso muscle/tendon stretch in the backswing.

The other way is to interpret the [b]same[/b] results differently. Note that golfers who generated greater ball velocity speeds had similar degrees of hip rotation in the backswing as golfers who had slower ball velocity speeds - roughly in the range of 45-50 degrees. The two biggest differences between the two groups were i) degree of shoulder turn in the backswing (average of 10 degrees more) and ii) speed of pelvic and shoulder rotation in the downswing (faster shoulder and pelvic rotation). The golfers who generated greater ball velocity speeds had a bigger shoulder turn in the backswing and faster shoulder/hip turn speeds in the downswing. What is the likely mechanism for this difference? I don't think that it relates to a greater degree of shoulder-hip turn differential and stretching of the torso muscles/tendons. I think that a more likely explanation is as follows.

Consider the example of TW.

Look at this video of TW.

[url="http://www.youtube.com/watch?v=4wxn0sIkJH8&mode=related&search="]TW swing video[/url]

We can all agree that TW has an amazing ability to turn his pelvis at the start of the downswing and generate a fast hip turn speed. I believe that TW can do that because he has well developed abdominal muscles and is a superb athlete with perfect coordination. He would be able to do that if his hip turn in the backswing was 45 degrees, rather than 30 degrees. In other words, the ability to turn the hips at the start of the downswing is not dependent on McLean's coil/uncoil theory - it is something that good golfers have for inherently athletic reasons.

Now consider what happens when TW starts the downswing with a very fast hip turn. That very fast transition hip move helps start the shoulder turn as it promotes the dropping of the right shoulder down towards the ball as the club becomes "slotted". In other words, the hip torquing action helps activate the shoulder downswing move by torquing the entire torso. Now if TW gets a 20 degree greater degree of shoulder rotation in the backswing (110 degrees instead of 90 degrees) then he will likely be able to generate a faster shoulder turn speed in the downswing. The combination of a faster shoulder turn speed and a faster hip turn speed translates into a faster clubhead speed. In other words, my biomechanical explanation doesn't need to invoke a controversial theory - that stretching of torso muscles/tendons is[b] significantly [/b]responsible for faster clubhead speeds in golfers who have a greater degree of shoulder-hip separation in the backswing.

What do you think of my interpretative conclusion - based on that study's results?

Addendum added 12/14.

Robby - another point that I want to add to my argument.

If one has an extra 10 degree of shoulder rotation, then the mid-upper torso muscles that will cause the shoulders to rotate in the downswing are lengthened. If they are lengthened, then they have a greater distance to shorten during the downswing phase of the golf swing. Ignoring the potential effect of stretch-induced force enhancement of muscle contraction, let's presume that the mid-upper torso muscles have a "fixed" efficiency of muscle contraction. While executing their "fixed" efficiency of muscle contraction during the early-mid downswing phase of the golf swing, they are contracting for a longer distance per unit time (because their length at the end-backswing position is greater secondary to the extra 10 degrees of shoulder turn) and during each miilisecond of contraction time they are imparting a force to the shoulder turn. If they are contracting for a longer muscle-shortening distance, and are imparting a "fixed" amount of force (energy) for each miilimetre of muscle shortening, then they will impart a greater total amount of force (energy) during their contractile phase. The end-result is that it will cause the shoulders to turn faster. Another additional/synergistic factor to consider is that the shoulder turn arc is greater if there is an extra 10 degrees of shoulder turn during the backswing - and that allows the shoulders to accumulatively acquire greater velocity prior to ball impact. In other words, I have provided an explanation for the greater shoulder turn speed in the HBV group that has nothing to do with stretch-induced force enhancement of muscle contraction.


Jeff.

[JeffMann]

HF

You write-: "The counterpoint to the biceps example is the triceps. Try thowing a football with the arm lengthened at it's normal resting position (of course moving it overhead but still relatively straight) and tell me how you can achieve maximum throw distance or speed without bending the elbow considerably (around 90 degrees). You can't, because you aren't using the powerful triceps muscle without first bending at the elbow to get the triceps into a normal elongated position, not an "overstretched" one."

I think that you are wrong. The fact that the triceps muscle cannot contribute to throw power is not due to the fact that the triceps is [b]not[/b] in the "normal elongated position". It is due to the fact that the triceps cannot generate power unless it shortens, and it cannot shorten if the elbow is fully extended. A muscle needs to shorten to generate isotonic throw power. Now if the elbow joint was capable of extending beyond straight, I believe that the triceps muscle would still have ample ability to shorten further when it has a baseline length [b]equal[/b] to its length when the elbow is straight.

Jeff.

[slicefixer]

One thing that I think NEEDS to be "interjected" into this discussion is this........

Are we talking about the X Factor's ability to develop rotational core speed IRREGARDLESS of it's effect on the arms/club/clubhead.......just in regards to "raw" speed? Are we debating whether the X Factor is the single most important deteminant of "power"/"distance?" We can't forget that RAW SPEED doesn't matter if the clubhead won't square up during "impact"............ACCURACY, while less important than it was just a few years ago, is STILL a BIG part of most of our golf games..................

IMOP, the X Factor, if misused/misinterpreted could be disasterous to a person golf game...........I've NEVER bought into the "restrict the hips" stuff.........basically just guarantees you that you'll get your arms "stuck"/"trapped" behind your body in the downswing and then be FORCED to SLOW the core to allow the to catch up so tha' face can square up..........NOT going to do a player much good to create a HUGE X Factor and then use it, but, the arms/club are NOT "there" at impact......

In fact, I think that video of TW (obviously hitting a driver) that has shown up in this thread several times is a TERRIBLE example of a proper downswing pivot.......basically just a TERRIBLE "spin out"........hell, I don't think I KNOW it is..........is there a large amount of "dynamic X Factor?" (btw HF, I LUV that term....new one for my "arsenal"...hehehe)........heck yes.......have Tiger's hips "run off and left" his shoulders?......YES.........is the right hip now "in the way" making it basically impossible for him to "turn throught the ball?"........yep...IMOP.......just watch him "sling that clubhead"......watch the DRASTIC difference in Tiger's footwork/release from an iron to a driver.......probably the only player of consequence I've ever seen with TWO entirely different "pivots".......one for his irons and "controlled shots" is fantastic.....perfect........the other with his driver when he goes into "full nuke mode" is beyond awful........IMOP.......just makes no sense to me.........but, it sure hasn't stopped him from being the best there has ever been so who really cares, but, it IS the "why" behind why TW is a TERRIBLE driver of the ball when compared to the GREAT players of the past.......Hogan/Snead/Nicklaus, etc..........

IMOP, there are SO many other factors that go into a golf swing, besides a persons X Factor, that determine how effective a golf swing they create/ingrain/"own".........

- the "quality" of their FUNDAMENTALS.....primarily grip and posture.........
- the CLUBHEADS path/angle of attack/ARC........
- the SIZE of the clubheads ARC
- the SHAPE of the clubheads ARC........
- the "SUPPORT behind the blow".........
- the "positioning" of the body to the arms/club in the impact zone..........


IMOP, those are just 6 things that are equally, if not MORE, important than a persons X Factor......in both determining distance/power AND accuracy..............I could probably think of a half dozen more too........anyway, MOP.........

[Veritas]

I will read and attempt to reply about the paper as soon as possible but that will probably not be until tonight or sometime tomorrow. For some reason my advisor may not think talking about golf biomechanics is the best use of my time in the lab. Although, it certainly could be worse.

[hoganfan924]

[quote name='JeffMann' post='824195' date='Dec 14 2007, 10:22 AM']HF
I think that you are wrong. The fact that the triceps muscle cannot contribute to throw power is not due to the fact that the triceps is [b]not[/b] in the "normal elongated position". It is due to the fact that the triceps cannot generate power unless it shortens, and it cannot shorten if the elbow is fully extended. A muscle needs to shorten to generate isotonic throw power. Now if the elbow joint was capable of extending beyond straight, I believe that the triceps muscle would still have ample ability to shorten further when it has a baseline length [b]equal[/b] to its length when the elbow is straight.

Jeff.[/quote]


Gee, thanks for pointing that I'm "wrong" again! Who ever suggested that muscles contract isometrically to produce motion? We are saying the same thing. A muscle has to contract and shorten to produce motion and produce power. It cannot be in a fully contracted position and produce motion from there, it must first be elongated. I think I'll pass on the elbow surgery, I'm happy with how far I can throw a ball.

BTW, the formulas I posted earlier are not "mine," they are the definitions of work and power according to the laws of physics. As I recollect, in "search for the perfect swing," the authors calculated that a tour pro has to generate approximately 3.5 peak horsepower in order to hit a driver at their typical speed (1968 speed) and I think an average HP of around 2 (not sure, don't have access to the book right now). 1 HP = 33,000 lb-ft/min. (550 lb-ft./sec.) Since a downswing takes about .25 sec. in a tour pro, that means that the amount of work by the body performed in a downswing is 1100 lb-ft., the equivalent of lifting a 100 lb. weight 11 feet! Ever wonder why you need a backswing? That's why. What do you think performs that work? MUSCLES! Tendons have no capacity to perform work on their own without first being stretched by a muscle, although they can certainly store energy and return it (like a spring) as Rdb.. has pointed out.

[Texsport]

I'd think that,no matter how much power a backswing develops, to hit the ball further, that power can't be lost in the process of delivering the clubface. Power leaks in the downswing, or the lack of leaks, are, at least as, if not more important than backswing power buildup.

Texsport

[hoganfan924]

[quote name='rdbivyleagun' post='824231' date='Dec 14 2007, 11:04 AM']I will read and attempt to reply about the paper as soon as possible but that will probably not be until tonight or sometime tomorrow. For some reason my advisor may not think talking about golf biomechanics is the best use of my time in the lab. Although, it certainly could be worse.[/quote]

Maybe you can convince him that the biomechanics of the spine in a golfswing is relevant to you PHD dissertation.

[JeffMann]

HF

I am glad that you have decided not to have elbow surgery. It wouldn't improve your golf game! :-)

It is also nice to know that you are happy with your football throwing ability. I am sure that it is good, although I don't think that your triceps muscle is playing a significant role in your ability to throw the ball a long distance.

I agree with you - torso muscle power is needed to generate a powerful downswing action. However, that torso muscle power can be efficiently actuated if one's hip turn is 30 degrees, or 40 degrees, or 50 degrees. I think that one doesn't need to stretch the torso muscles to optimise the torso muscles' ability to contract efficiently. If one turns the shoulders an extra 20 degrees, then extra shoulder speed can be generated because the mid-upper torso muscle shorten [b]more[/b] ( mid-upper torso muscles have a greater distance to travel during their shortening phase) and not because the torso muscles shorten more efficiently due to pre-stretching. If the mid-upper torso muscles shorten at a "fixed" speed ("fixed" degree of efficiency), but the shoulder turn is greater, then the shoulders will turn at a faster speed if their speed is measured at a certain time-point in the downswing eg. mid-downswing or late downswing.

Jeff.

[slicefixer]

[quote name='Texsport' post='824246' date='Dec 14 2007, 12:15 PM']I'd think that,no matter how much power a backswing develops, to hit the ball further, that power can't be lost in the process of delivering the clubface. Power leaks in the downswing, or the lack of leaks, are, at least as, if not more important than backswing power buildup.

Texsport[/quote]


EXACTLY what I was trying to say above.........my primary point anyway........glad your here now Tex!

I'll now slide back into the background and let the anatomy, physics, and biomechancial experts have at it.........

[rankoutsider]

i've followed this intently, and will defer to rdb on the science. i know him off-list, and can confirm, if his erudition doesn't do the trick, that he is what he says he is. i am certain that he has the scientific part of it right.

i want to inject something along the lines that slice and texsport are saying and get some feedback. i've always felt that one of the biggest difficulties in the golfswing is that, just after the halfway point in the backswing, the club, hands, arms, etc. are actually moving closer to the target. somewhere around the 60 % point, they are going forward. if you keep turning your hips through all of this & have reasonable flexibility, you WILL for certain get your weight moving forward before the club stops at the top. this is not death or anything, but it is counter-productive. what the X factor articulates is a way to understand the optimum relationship between shoulders and hips to produce a swing that has the weight going back and stopping, even while the clubhead is moving forward in the backswing (between say 60% and wherever the top of the backswing is relative to parallel for a golfer). it is fine to go past parallel, or well short of it, if your weight is either moving back into your backside, or has stopped. if your weight is going forward, you will not hit the ball as well as you can, and your back leg will extend, which will also deprive you of power. what MacLean is talking about with the X factor is this state of tension with the hands going forward for the last quarter or so (or a bit more) BUT the weight going backward throughout the swing.

[slicefixer]

Just read the entire article........outstanding.......I agree with 100% of what McClean says in the article..........the only two "problems" I have with the article is I think he should have STRESSED that the head has to "turn to the right as well as to the left"......."If you don't either pre set your head "cocked"/"turned" right OR allow your head to "rotate right" in the backswing you'll NEVER get "wound up"......"and, IF you never get wound up you've got nothing to unwind"...................the other is I disagree that there MUST be a "substantial" lateral movement in the transition......in fact, I KNOW that it doesn't have to be "substantial" at all.......I really feel like this is as much "semantics" as anything......or a disagreement about the "amount" more than anything............to print so many garbage instructional articles occasionally GD get's it right........

[hoganfan924]

[quote name='slicefixer' post='824399' date='Dec 14 2007, 01:40 PM']Just read the entire article........outstanding.......I agree with 100% of what McClean says in the article..........the only two "problems" I have with the article is I think he should have STRESSED that the head has to "turn to the right as well as to the left"......."If you don't either pre set your head "cocked"/"turned" right OR allow your head to "rotate right" in the backswing you'll NEVER get "wound up"......"and, IF you never get wound up you've got nothing to unwind"...................the other is I disagree that there MUST be a "substantial" lateral movement in the transition......in fact, I KNOW that it doesn't have to be "substantial" at all.......I really feel like this is as much "semantics" as anything......or a disagreement about the "amount" more than anything............to print so many garbage instructional articles occasionally GD get's it right........ [/quote]

Slice,

I agree it's an outstanding article and with your conclusion that GD finally gave us a good one (amongst all the garbage). The only aspect of McLean's conclusions that I have any reservations about is the "head swivel" being an X-factor. I would be very curious to know whether the amount of head swivel was cross plotted with hip and shoulder turn. My suspicion is that it is possible head swivel is merely an effect of what happens with shoulder rotation, i.e. tour pros have the shoulders more open at impact on average than 17 handicappers. Perhaps Points can enlighten us. I am genuinely curious.

[Points]

A couple of things about the head movement. On the backswing, not all players heads are going to swivel that much based on eye dominance. Right handed golfer who are left eye dominant are going to much more apt to wind on the backswing than a very right eye dominant person. May see a slight amount more lateral motion in right eye dominant player.

In terms of the head on the downswing, most amateurs actually get there shoulders pretty open at impact. Unfortunately, it is a result of poor body motion. The more over the top the swing the more the shoulders open early in the downswing so the x relationship is lost. The correlation between shoulders and head was not specifically addressed. I am sure Dr. Neal would have more information in regards to this as his has spent his career on golf bio dianamics.

I find this thread very amuzing in the sense that Jeffman is very quick to point out how others are wrong yet admits no mistake. He starts a thread ripping apart a man's work and then simply says I misread a thing or two. How nice it must be.

[hoganfan924]

[quote name='Points' post='824542' date='Dec 14 2007, 03:53 PM']A couple of things about the head movement. On the backswing, not all players heads are going to swivel that much based on eye dominance. Right handed golfer who are left eye dominant are going to much more apt to wind on the backswing than a very right eye dominant person. May see a slight amount more lateral motion in right eye dominant player.[/quote]
So glad I'm left eye dominant. I used to pre-set my head back like Nicklaus, maybe I should try that again!

[quote]In terms of the head on the downswing, most amateurs actually get there shoulders pretty open at impact. Unfortunately, it is a result of poor body motion. The more over the top the swing the more the shoulders open early in the downswing so the x relationship is lost. The correlation between shoulders and head was not specifically addressed. I am sure Dr. Neal would have more information in regards to this as his has spent his career on golf bio dianamics.[/quote]
Hmm, very interesting! The difference between the pros and am's then I think would be seen in the amount of shoulder/hip X-factor at impact. As you know, many am's have the shoulders already catching and even overtaking the hips at impact.

[quote]I find this thread very amuzing in the sense that Jeffman is very quick to point out how others are wrong yet admits no mistake. He starts a thread ripping apart a man's work and then simply says I misread a thing or two. How nice it must be.[/quote]
Nothing more to add!

[slicefixer]

[quote name='hoganfan924' post='824413' date='Dec 14 2007, 02:48 PM'][quote name='slicefixer' post='824399' date='Dec 14 2007, 01:40 PM']Just read the entire article........outstanding.......I agree with 100% of what McClean says in the article..........the only two "problems" I have with the article is I think he should have STRESSED that the head has to "turn to the right as well as to the left"......."If you don't either pre set your head "cocked"/"turned" right OR allow your head to "rotate right" in the backswing you'll NEVER get "wound up"......"and, IF you never get wound up you've got nothing to unwind"...................the other is I disagree that there MUST be a "substantial" lateral movement in the transition......in fact, I KNOW that it doesn't have to be "substantial" at all.......I really feel like this is as much "semantics" as anything......or a disagreement about the "amount" more than anything............to print so many garbage instructional articles occasionally GD get's it right........ [/quote]

Slice,

I agree it's an outstanding article and with your conclusion that GD finally gave us a good one (amongst all the garbage). The only aspect of McLean's conclusions that I have any reservations about is the "head swivel" being an X-factor. I would be very curious to know whether the amount of head swivel was cross plotted with hip and shoulder turn. My suspicion is that it is possible head swivel is merely an effect of what happens with shoulder rotation, i.e. tour pros have the shoulders more open at impact on average than 17 handicappers. Perhaps Points can enlighten us. I am genuinely curious.
[/quote]


I'd agree 100%..........but, I think the point he's trying to make is you can't "turn through it"/"release the X Factor" IF you keep your head glued to the ball/ground.......as we both know, when the head is frozen the range of motion of the core is GREATLY reduced.......I just wish he'd pointed out that ya' gotta 'let the head "turn" or pre-set it "turned" at address IF you want to be able to "wind up" and "getcha' some X Factor"......hehehehe

[Veritas]

Good times ahead.

Ok I have read the article that I suggested earlier on in this post and have my conclusions. First, I would like to point out that I have only been golfing for a year and my swing theory is pretty much infantile and am getting my first lessons this spring. So please feel free to correct me if I am wrong about some part of swing theory. That was my disclaimer.

Now to the stuff that I do know. Hmm where to start. I'm going to start by saying the quality of this paper was very good and scientifically rigorous. The statistical tests used in this was dead on and exactly what I hoped to see. The main stats that are relevant to this discussion are the pearson pairwise correlations, which I will only refer to as a correlation from here on out. The correlation is exactly what it sounds like, it tells you whether something is correlated to something else. However, I think they sell their data short by calling some of their correlations as moderate. It is taught in any rigorous stat class that a correlation of .5 or greater is a strong correlation, a .3-.5 is moderate, and anything below .3 is low. This especially true in biological data when the variability and confounding factors are large and many. So I have no idea why they would refer to a correlation over .5 as moderate. As a result, I will follow the the correlation ranges stated above, as I was taught and believe to be correct. Also, I'm going to talk about significance of a result. mostly by reporting p values. A p value can be interpreted like this. p = .05 means that there is a 5 % chance that the result occurred by chance. Usually a result lower than p=.05 is considered significant and anything above is not. Ok boring stuff over.

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 seperation/xfactor and should not be argued. However, correlations don't mean causation, only that they are somehow related.

The argument from here on out is what is the actual mechanism of this correlation and why do we see it. Jeff you say
" i) degree of shoulder turn in the backswing (average of 10 degrees more) and ii) speed of pelvic and shoulder rotation in the downswing (faster shoulder and pelvic rotation)" are the biggest differences between the golfers and use this to base your theory. When you look at the correlations you see that the degree of shoulder turn (correlation =.19, p=.056) has a low and insignificant correlation value. This basically tells us that the shoulder turn does not really affect ball speed that much on its own. So it is really a non factor in this discussion. Also, the speed of pelvic rotation has only a moderate correlation that is significant (.36, p=.001), but this is not on the same level of the other correlations we will talk about in a second. As a result, of these two correlations it is really tough to support your arguments that are mostly based on tiger woods/a golfer's hip turn speed and shoulder turn.

Now the upper torso rotational velocity does have a large correlation and is significant (.59, p =.001). I actually think this one makes a lot of sense that, hey, if my upper body is rotating quickly then so will the club. What I think is going on here is that if they did a correlation between torso-pelvic separation and upper torso rotational velocity, which they didn't, they would find a large significant correlation. This is where you see torso-pelvic separation working in that this upper torso rotational velocity is caused by and is a function of the torso-pelvic separation. Sorry Jeff, but the correlation values really make it tough to impossible to go with your theory. The huge player here is really the x-factor and now I want to talk about what I believe the mechanism is.

If you have been following this thread then you know I have been touting muscle-tendon elastic storage of energy with quite a bit of resistance but I am just going to paste a couple of paragraphs of the article to do the talking for me here

"From a biomechanics perspective, this belief that
torso – pelvic separation is an important contributor
to increasing driving distance has merit. The action
of the torso during the golf swing can be classified
as a stretch – shortening movement (Fletcher &
Hartwell, 2004). 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 (Ettema, Huijing, & De
Haan, 1992; Ettema, Huijing, Van Ingen Schenau, &
De Haan, 1990a; Ettema, Van Soest, & Huijing,
1990b). 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. (Finni, Ikegawa, Lepola, &
Komi, 2003; Komi, 2000).
We can potentially apply these stretch – shortening
principles to the golf swing. Electromyography
studies have demonstrated that the trunk muscles
including erector spinae, abdominal obliques, rectus
abdominis, latissimus dorsi, and gluteals are active
during the backswing (Horton, Lindsay, &Macintosh,
2001; Pink, Jobe, & Perry, 1990; Pink, Perry, &
Jobe, 1993; Watkins, Uppal, Perry, Pink, & Dinsay,
1996). Additionally, during the backswing, separation
between the upper torso and pelvis results in
stretching (eccentric loading) of these activated trunk
muscles, which could ultimately contribute to the
powerful concentric trunk muscle contractions
needed to drive the ball. These activated muscles
play a significant role in generating club head speed
during the downswing (Horton et al., 2001; Pink
et al., 1990, 1993; Watkins et al., 1996). Thus, it is
hypothesized that as this separation between the
upper torso and pelvic rotation increases, the
resulting increase in concentric contraction during
the golf swing will increase club head speed, resulting
in increased ball velocity and driving distance."

Jeff this is all the data you have been requesting throughout the argument in these paragraphs and backed up by the references. There are the muscles involved. There is the proof they are activated during the swing. There is the scientific evidence that a stretch induced increase in force is seen within muscle. I really think the ball is in your court to provide scientific evidence for your theory. This scientific evidence goes against what you are saying and as you can see quite a few studies support this theory. You would be hard pressed to call it junk science at this point. I really don't think the theory is considered controversial by many people other than you. I actually think your theory is the controversial one and is the one that needs some scientific support.

I would like to point out that your addendum about the amount of time the muscle can produce force and act upon the body and increase velocity is correct and is a factor as well. I would also like to point out that it is the exact argument Hoganfan made in the second post and in which you tore apart and found "unconvincing". I think that is something you should probably acknowledge.

Finally, the golf swing is a performed by a biological biomechanical system and there are many, many variables at work here. The x-factor is by far not the only thing that contributes to the power in a golf swing but can be seen here to be a large factor. However, by itself, as slicefixer, points, and many others have pointed out, it is still just a factor. You must take into account a lot of things in addition to the x-factor to put together a solid swing.

Ok I'm done. Does this take the record for longest post ever?

[slicefixer]

[quote name='rdbivyleagun' post='824991' date='Dec 14 2007, 11:22 PM']Good times ahead.

Ok I have read the article that I suggested earlier on in this post and have my conclusions. First, I would like to point out that I have only been golfing for a year and my swing theory is pretty much infantile and am getting my first lessons this spring. So please feel free to correct me if I am wrong about some part of swing theory. That was my disclaimer.

Now to the stuff that I do know. Hmm where to start. I'm going to start by saying the quality of this paper was very good and scientifically rigorous. The statistical tests used in this was dead on and exactly what I hoped to see. The main stats that are relevant to this discussion are the pearson pairwise correlations, which I will only refer to as a correlation from here on out. The correlation is exactly what it sounds like, it tells you whether something is correlated to something else. However, I think they sell their data short by calling some of their correlations as moderate. It is taught in any rigorous stat class that a correlation of .5 or greater is a strong correlation, a .3-.5 is moderate, and anything below .3 is low. This especially true in biological data when the variability and confounding factors are large and many. So I have no idea why they would refer to a correlation over .5 as moderate. As a result, I will follow the the correlation ranges stated above, as I was taught and believe to be correct. Also, I'm going to talk about significance of a result. mostly by reporting p values. A p value can be interpreted like this. p = .05 means that there is a 5 % chance that the result occurred by chance. Usually a result lower than p=.05 is considered significant and anything above is not. Ok boring stuff over.

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 ball speed and should not be argued. However, correlations don't mean causation, only that they are somehow related.

The argument from here on out is what is the actual mechanism of this correlation and why do we see it. Jeff you say
" i) degree of shoulder turn in the backswing (average of 10 degrees more) and ii) speed of pelvic and shoulder rotation in the downswing (faster shoulder and pelvic rotation)" are the biggest differences between the golfers and use this to base your theory. When you look at the correlations you see that the degree of shoulder turn (correlation =.19, p=.056) has a low and insignificant correlation value. This basically tells us that the shoulder turn does not really affect ball speed that much on its own. So it is really a non factor in this discussion. Also, the speed of pelvic rotation has only a moderate correlation that is significant (.36, p=.001), but this is not on the same level of the other correlations we will talk about in a second. As a result, of these two correlations it is really tough to support your arguments that are mostly based on tiger woods/a golfer's hip turn speed and shoulder turn.

Now the upper torso rotational velocity does have a large correlation and is significant (.59, p =.001). I actually think this one makes a lot of sense that, hey, if my upper body is rotating quickly then so will the club. What I think is going on here is that if they did a correlation between torso-pelvic separation and upper torso rotational velocity, which they didn't, they would find a large significant correlation. This is where you see torso-pelvic separation working in that this upper torso rotational velocity is caused by and is a function of the torso-pelvic separation. Sorry Jeff, but the correlation values really make it tough to impossible to go with your theory. The huge player here is really the x-factor and now I want to talk about what I believe the mechanism is.

If you have been following this thread then you know I have been touting muscle-tendon elastic storage of energy with quite a bit of resistance but I am just going to paste a couple of paragraphs of the article to do the talking for me here

"From a biomechanics perspective, this belief that
torso – pelvic separation is an important contributor
to increasing driving distance has merit. The action
of the torso during the golf swing can be classified
as a stretch – shortening movement (Fletcher &
Hartwell, 2004). 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 (Ettema, Huijing, & De
Haan, 1992; Ettema, Huijing, Van Ingen Schenau, &
De Haan, 1990a; Ettema, Van Soest, & Huijing,
1990b). 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. (Finni, Ikegawa, Lepola, &
Komi, 2003; Komi, 2000).
We can potentially apply these stretch – shortening
principles to the golf swing. Electromyography
studies have demonstrated that the trunk muscles
including erector spinae, abdominal obliques, rectus
abdominis, latissimus dorsi, and gluteals are active
during the backswing (Horton, Lindsay, &Macintosh,
2001; Pink, Jobe, & Perry, 1990; Pink, Perry, &
Jobe, 1993; Watkins, Uppal, Perry, Pink, & Dinsay,
1996). Additionally, during the backswing, separation
between the upper torso and pelvis results in
stretching (eccentric loading) of these activated trunk
muscles, which could ultimately contribute to the
powerful concentric trunk muscle contractions
needed to drive the ball. These activated muscles
play a significant role in generating club head speed
during the downswing (Horton et al., 2001; Pink
et al., 1990, 1993; Watkins et al., 1996). Thus, it is
hypothesized that as this separation between the
upper torso and pelvic rotation increases, the
resulting increase in concentric contraction during
the golf swing will increase club head speed, resulting
in increased ball velocity and driving distance."

Jeff this is all the data you have been requesting throughout the argument in these paragraphs and backed up by the references. There are the muscles involved. There is the proof they are activated during the swing. There is the scientific evidence that a stretch induced increase in force is seen within muscle. I really think the ball is in your court to provide scientific evidence for your theory. This scientific evidence goes against what you are saying and as you can see quite a few studies support this theory. You would be hard pressed to call it junk science at this point. I really don't think the theory is considered controversial by many people other than you. I actually think your theory is the controversial one and is the one that needs some scientific support.

I would like to point out that your addendum about the amount of time the muscle can produce force and act upon the body and increase velocity is correct and is a factor as well. I would also like to point out that it is the exact argument Hoganfan made in the second post and in which you tore apart and found "unconvincing". I think that is something you should probably acknowledge.

Finally, the golf swing is a performed by a biological biomechanical system and there are many, many variables at work here. The x-factor is by far not the only thing that contributes to the power in a golf swing but can be seen here to be a large factor. However, by itself, as slicefixer, points, and many others have pointed out, it is still just a factor. You must take into account a lot of things in addition to the x-factor to put together a solid swing.

Ok I'm done. Does this take the record for longest post ever?[/quote]


GREAT stuff RB.........A sincere THANKS for the effort! BTW, your's is SHORT compared to some of the novels I've "composed" over the years........hehehehe........

[dana dahlquist]

This is off topic so if your into reading how the x-factor works in this statement it will fall short

1. hit it solid
2. workout and be stretch
3. work out for fast movements
4. forget trying to coil anything

[hayam]

[quote name='dana dahlquist' post='825117' date='Dec 15 2007, 12:00 AM']This is off topic so if your into reading how the x-factor works in this statement it will fall short

1. hit it solid
2. workout and be stretch
3. work out for fast movements
4. forget trying to coil anything[/quote]


Dana, what do you mean by will fall short.

Thanks