Anatomy of the Golf Swing Blog-post No. 3 The Trunk/Torso [All descriptions are for a right-handed golfer]. The trunk or torso refers to the entire body except for the head/neck, the arms and the legs.
What are the anatomical structures in the torso region of the body? Basically, the spine (see pic below left) - of the thoracic region (with it’s attached rib-cage see pic below right); the lumbar region (with its 5 big vertebrae, right below the section where the ribs attach, see pic at the bottom left); and the sacral region, which serves to attach the spine to the two ‘hip bones’ (also known as innominate bones, coxal bones or pelvic bones, see pic bottom right) of the hip region, and thus, via a ‘socket’ in each of those, to the ‘ball’ of the thigh-bone (ie. the femur).
What movements is the torso supposed to make during the golf swing? Mainly, we are told, a rotation, and a great deal of study has been done on the amount of rotation desirable, based, as always, on what the best players in the world do. The
Titleist Performance Institute (TPI) has become a leader in the field of golf fitness and improving upon the ‘physical limitations’ of golfers. So, perhaps a good place to start is with what TPI has to say about what the trunk’s role in the golf swing. (One website which lists and describes the 12 TPI faults:
http://www.finishfirstsports.com/the-twelve-most-common-swing-faults.html) Of the 12 most commonly seen faults in golfers with limitations (according to TPI), we can ascribe 6 to the torso-region. During the set-up there could be ‘C’ or ‘S’ posture which describe the curvature of the spine (see http://www.mytpi.com/improve-my-game/swing-characteristics/c-posture). During the backswing there could be a ‘flat shoulder plane’ (a line joining the shoulders would be fairly horizontal, instead of perpendicular to the spine’s forward angle (see
http://www.mytpi.com/improve-my-game/swing-characteristics/flat-shoulder-plane and pics below); and ‘reverse spine angle’ (with the spine leaning towards the target - see a screen shot below from the myTPI website). Correct and flat shoulder planes:
Reverse spine angle:
During the downswing there could be ‘loss-of-posture’ and ‘early extension’ (hips and spine straighten out of posture too early in the downswing); as well as ‘hanging back’ (see screen shots below from the myTPI website). Hanging back:
Add to this list the X-Factor and the X-Factor Stretch; as well as the Hip-Rise (two parts of the
Triple X-Factor), observed by
Jim McLean. McLean observed how the 5 longest hitters on the US Tour had a big angle between their shoulder and hip rotations, while the shortest had a small angle. This he termed the X-Factor. As pro-golfers start their downswing, they are able to increase the angle between the hips (which lead during the downswing) and the shoulders (which lag behind). This he termed the X-factor Stretch, which is considered a key biomechanical principle for increasing distance through stretching muscles which can then contract more forcefully, much as a stretched elastic band can. Finally, McLean has noticed a ‘hip rise’ made by the most powerful ball-strikers. X-factor (below left) and hip-rise (below right):
So, summing up, for the production of power, a golfer should have a neutral (comfortably straight) spine at address. During the backswing, the thorax should rotate a lot relative to the hips; and the shoulders should rotate perpendicular to the spine angle which was set up at address. During the downswing, the spine should remain in its forward flexion, at least until impact, and the left hip should rise at that stage. The problems begin right now. A ‘C’ spine can require a lot of physical rehabilitation not every golfer can be bothered with. An ‘S’ spine is not as common, and is often artificially created by golfers, based on instruction they’ve misunderstood (such as ‘stick your butt out’). How can any sport expect even athletes with the healthiest spines to rotate one part of it against another? The cervical, thoracic and lumbar spines are parts of a whole. Imagine taking a plastic golf club and twisting its clubhead one way, its shaft another, and its grip end a third! Most ironical, to my mind, is that a world of experts have not noticed that when the shoulders ‘rotate’ perpendicular to the spine, the movement is no rotation at all! It’s a side-bend, technically known as a lateral flexion. Look at a standing lateral flexion and The TPI definition of rotation of ‘shoulders around spine’. BOTH pics below are LATERAL FLEXION!
These moves can cause great ball-striking inefficiency as the body must side-bend the right side while the lower body tries to start a rotation from this laterally flexed position; the arms must be dropped down; and the wrists straightened. Don’t forget that the left hip must rise at some stage during the downswing too! [TOO MANY MOVES, TOO LITTLE TIME]. In fact, in less skilled golfers, it is the left lateral flexion of the backswing requiring to be un-done, along with so many other joint-movements, which often causes those golfers to make a simplistic straight-line movement during the downswing which we term ‘hitting from the top’.
WHAT SENSE DOES IT MAKE FOR THE RIGHT SIDE OF THE TRUNK/TORSO TO BE HIGHER AT THE TOP WHEN AT ADDRESS AND AT IMPACT IT IS LOWER? Likely injuries include: to the left and right knees (left as it has to straighten abruptly while being torqued rapidly; and right as it has stretching forces on its inside and compressive ones on its outside). Also to the left hip which is becomes straightened excessively while trying to side-bend the right side; to right side facet-joints; as well as to the left shoulder, elbow and wrist in cases of over-the-top impacts. The Minimalist Golf Swing positions the torso/trunk in right lateral flexion (with the neck/head matched, see previous post), from address (A) to impact (I), which reduces one extra re-positioning procedure during the downswing, and aids ball-striking efficiency. This positioning of the trunk/torso in right lateral flexion from A to I, is, in fact, the
MAGIC MOVE of the MINIMALIST GOLF SWING, and there are many reasons why it truly is a ‘magic move’ (see rationale of MGSS 2013 on the blog page titled ‘the minimalist golf swing - what it is’). However good your ball-striking, you cannot experience as pure a contact as with the right side down from A to I.
After all, if the body is supposed to right-side bend plus left side rise (hip rise), during the downswing, it’s not as easy as if all it has to do is left side rise! Incidentally, even less-skilled golfers, or those who are older, or not as strong (see pic above, specifically with regard to the main 'rise' ie. shoulder rise), get a very good left hip rise (and, more importantly, shoulder rise) with the MGSS, as one extra move is done away with. It is only young, strong, golfers who can have enough muscle strength and thus speed to do both at the same time for maximal power. (Study some impact positions of Seniors of the Champions Tour in posts of May 2013 to see what that means). Incidentally, The Minimalist Golf Swing pre-sets the ENTIRE SPINE in a PURE (ie. horizontal plane, as required during the downswing) ROTATION. This rotation creates very slightly more right side bend (too much can result in hitting behind), which the golfer then has to maintain during the backswing. The combination produces all 3 biomechanical principles required for power and direction success (for those in the know: stretch-shortening cycle, kinematic sequence and GRF) WITHOUT the golfer's VOLITION - ie. AUTOMATICALLY.
What movements is the torso supposed to make during the golf swing? Mainly, we are told, a rotation, and a great deal of study has been done on the amount of rotation desirable, based, as always, on what the best players in the world do. The Titleist Performance Institute (TPI) has become a leader in the field of golf fitness and improving upon the ‘physical limitations’ of golfers. So, perhaps a good place to start is with what TPI has to say about what the trunk’s role in the golf swing. (One website which lists and describes the 12 TPI faults: http://www.finishfirstsports.com/the-twelve-most-common-swing-faults.html) Of the 12 most commonly seen faults in golfers with limitations (according to TPI), we can ascribe 6 to the torso-region. During the set-up there could be ‘C’ or ‘S’ posture which describe the curvature of the spine (see http://www.mytpi.com/improve-my-game/swing-characteristics/c-posture). During the backswing there could be a ‘flat shoulder plane’ (a line joining the shoulders would be fairly horizontal, instead of perpendicular to the spine’s forward angle (see http://www.mytpi.com/improve-my-game/swing-characteristics/flat-shoulder-plane and pics below); and ‘reverse spine angle’ (with the spine leaning towards the target - see a screen shot below from the myTPI website). Correct and flat shoulder planes: 
During the downswing there could be ‘loss-of-posture’ and ‘early extension’ (hips and spine straighten out of posture too early in the downswing); as well as ‘hanging back’ (see screen shots below from the myTPI website). Hanging back: 
Add to this list the X-Factor and the X-Factor Stretch; as well as the Hip-Rise (two parts of the Triple X-Factor), observed by Jim McLean. McLean observed how the 5 longest hitters on the US Tour had a big angle between their shoulder and hip rotations, while the shortest had a small angle. This he termed the X-Factor. As pro-golfers start their downswing, they are able to increase the angle between the hips (which lead during the downswing) and the shoulders (which lag behind). This he termed the X-factor Stretch, which is considered a key biomechanical principle for increasing distance through stretching muscles which can then contract more forcefully, much as a stretched elastic band can. Finally, McLean has noticed a ‘hip rise’ made by the most powerful ball-strikers. X-factor (below left) and hip-rise (below right): 
So, summing up, for the production of power, a golfer should have a neutral (comfortably straight) spine at address. During the backswing, the thorax should rotate a lot relative to the hips; and the shoulders should rotate perpendicular to the spine angle which was set up at address. During the downswing, the spine should remain in its forward flexion, at least until impact, and the left hip should rise at that stage. The problems begin right now. A ‘C’ spine can require a lot of physical rehabilitation not every golfer can be bothered with. An ‘S’ spine is not as common, and is often artificially created by golfers, based on instruction they’ve misunderstood (such as ‘stick your butt out’). How can any sport expect even athletes with the healthiest spines to rotate one part of it against another? The cervical, thoracic and lumbar spines are parts of a whole. Imagine taking a plastic golf club and twisting its clubhead one way, its shaft another, and its grip end a third! Most ironical, to my mind, is that a world of experts have not noticed that when the shoulders ‘rotate’ perpendicular to the spine, the movement is no rotation at all! It’s a side-bend, technically known as a lateral flexion. Look at a standing lateral flexion and The TPI definition of rotation of ‘shoulders around spine’. BOTH pics below are LATERAL FLEXION! 
After all, if the body is supposed to right-side bend plus left side rise (hip rise), during the downswing, it’s not as easy as if all it has to do is left side rise! Incidentally, even less-skilled golfers, or those who are older, or not as strong (see pic above, specifically with regard to the main 'rise' ie. shoulder rise), get a very good left hip rise (and, more importantly, shoulder rise) with the MGSS, as one extra move is done away with. It is only young, strong, golfers who can have enough muscle strength and thus speed to do both at the same time for maximal power. (Study some impact positions of Seniors of the Champions Tour in posts of May 2013 to see what that means). Incidentally, The Minimalist Golf Swing pre-sets the ENTIRE SPINE in a PURE (ie. horizontal plane, as required during the downswing) ROTATION. This rotation creates very slightly more right side bend (too much can result in hitting behind), which the golfer then has to maintain during the backswing. The combination produces all 3 biomechanical principles required for power and direction success (for those in the know: stretch-shortening cycle, kinematic sequence and GRF) WITHOUT the golfer's VOLITION - ie. AUTOMATICALLY.