Post by dubiousgolfer on Jan 7, 2018 8:47:38 GMT -5
Dr Mann
I have been reviewing your article 'How to Optimally Rotate The Pelvis During The Downswing ' , specifically relating to the use of the left adductor magnus muscle (between P4-P6) and have a few questions (if you don't mind).
Issue 1
You have stated the following:
"Nonetheless, there is another biomechanical action that is likely in play during the early downswing that enables the externally rotating left femur to assist in the counterclockwise rotation of the pelvis during the early downswing - and that biomechanical action is due to the simultaneous muscular contraction of the left adductor magnus muscle.
There has only been one electromyography study performed by golf researchers on pelvic girdle area muscles during a golf swing and that is the study by Bechler et al [1]. In that study, the golf researchers found that the lead adductor magnus muscle is very active during the early-mid downswing."
And
"During the early downswing between P4 and P5, the left femur is being externally rotated due to contraction of the left-sided lateral pelvic rotator muscles so that the left thigh becomes increasingly externally rotated at P5 (relative to the scenario at P4). However, if the the left adductor magnus is also isometrically active during this early downswing time period, it can pull the left inferior pubic ramus towards the left thigh (as it is being externally rotated), thereby contributing to the counterclockwise rotation of the pelvis (which is mainly due to contraction of the right-sided lateral pelvic rotator muscles). I don't know how much the lead adductor magnus muscle contributes to the counterclockwise rotation of the pelvis during the early downswing - compared to the contribution from the right-sided lateral pelvic rotator muscles - but it may play a significant role."
Question 1.
I cannot understand how the pelvis can be rotated via contraction of left adductor magnus muscle unless the left femur is stabilised in space (ie weight loaded enough at the left hip joint). So is it a mandatory condition (before the adductor magnus muscle is contracted) that there is enough progressive weight loading on left femur between P4-P6 such that it is stabilised in space such that contraction of the adductor magnus will pull at its origin point 'inferior pubus ramus' in a clockwise direction?
Question 2.
You mention that the left adductor magnus muscle is 'isometrically active' between P4-P5 , so does this mean that it is not changing length? I always thought that an isometric contraction was associated with no movement (muscle firing but no movement of joint).
Issue 2
I found this you tube video showing which muscles are firing for 'deceleration' .
Question 1
If you look at 0:50 and 0:51 in slow motion , it seems that there is a momentary stall/counter-clockwise rotation at or near impact. I seem to remember that Rory McIlroy exhibits this same 'hip stall' . Are you aware of any biomechanical explanation for this phenomenon?
Question 2.
If you look at 1:18- 1:24 , the left adductor magnus muscle is starting to fire (to be honest ,I don't know what type of muscle contraction this portrays) and continues to contract past impact into the follow-through. But this video has confused me because its showing muscles that are being used in deceleration (see comment below)
"This 3D animation was constructed from extensive information from multi-camera video capture, 16 lead EMG (electromyogram) recording from 100 driver swings, and about a half a year of working with a 3D animator to perfectly reproduce time lines of muscle firing sequences in the golf swing. Although other muscles were captured by EMG, we are showing only muscles responsible for deceleration of motion."
If one looks at the major leg muscles being used to 'decelerate' motion from 1:18-1:24 , it seems that they are :
1. Left adductor magnus muscle
2. Right 'Posterior Thigh Muscles'(Biceps Femoris and Semitendinosus/Semimembranosus)
So now I am confused because it seems, from the the above video , that large left and right leg muscles are being used decelerate pelvis motion rather than assist in its rotation. Have I interpreted this correctly or have I gone wrong somewhere?
Regards
DB
I have been reviewing your article 'How to Optimally Rotate The Pelvis During The Downswing ' , specifically relating to the use of the left adductor magnus muscle (between P4-P6) and have a few questions (if you don't mind).
Issue 1
You have stated the following:
"Nonetheless, there is another biomechanical action that is likely in play during the early downswing that enables the externally rotating left femur to assist in the counterclockwise rotation of the pelvis during the early downswing - and that biomechanical action is due to the simultaneous muscular contraction of the left adductor magnus muscle.
There has only been one electromyography study performed by golf researchers on pelvic girdle area muscles during a golf swing and that is the study by Bechler et al [1]. In that study, the golf researchers found that the lead adductor magnus muscle is very active during the early-mid downswing."
And
"During the early downswing between P4 and P5, the left femur is being externally rotated due to contraction of the left-sided lateral pelvic rotator muscles so that the left thigh becomes increasingly externally rotated at P5 (relative to the scenario at P4). However, if the the left adductor magnus is also isometrically active during this early downswing time period, it can pull the left inferior pubic ramus towards the left thigh (as it is being externally rotated), thereby contributing to the counterclockwise rotation of the pelvis (which is mainly due to contraction of the right-sided lateral pelvic rotator muscles). I don't know how much the lead adductor magnus muscle contributes to the counterclockwise rotation of the pelvis during the early downswing - compared to the contribution from the right-sided lateral pelvic rotator muscles - but it may play a significant role."
Question 1.
I cannot understand how the pelvis can be rotated via contraction of left adductor magnus muscle unless the left femur is stabilised in space (ie weight loaded enough at the left hip joint). So is it a mandatory condition (before the adductor magnus muscle is contracted) that there is enough progressive weight loading on left femur between P4-P6 such that it is stabilised in space such that contraction of the adductor magnus will pull at its origin point 'inferior pubus ramus' in a clockwise direction?
Question 2.
You mention that the left adductor magnus muscle is 'isometrically active' between P4-P5 , so does this mean that it is not changing length? I always thought that an isometric contraction was associated with no movement (muscle firing but no movement of joint).
Issue 2
I found this you tube video showing which muscles are firing for 'deceleration' .
Question 1
If you look at 0:50 and 0:51 in slow motion , it seems that there is a momentary stall/counter-clockwise rotation at or near impact. I seem to remember that Rory McIlroy exhibits this same 'hip stall' . Are you aware of any biomechanical explanation for this phenomenon?
Question 2.
If you look at 1:18- 1:24 , the left adductor magnus muscle is starting to fire (to be honest ,I don't know what type of muscle contraction this portrays) and continues to contract past impact into the follow-through. But this video has confused me because its showing muscles that are being used in deceleration (see comment below)
"This 3D animation was constructed from extensive information from multi-camera video capture, 16 lead EMG (electromyogram) recording from 100 driver swings, and about a half a year of working with a 3D animator to perfectly reproduce time lines of muscle firing sequences in the golf swing. Although other muscles were captured by EMG, we are showing only muscles responsible for deceleration of motion."
If one looks at the major leg muscles being used to 'decelerate' motion from 1:18-1:24 , it seems that they are :
1. Left adductor magnus muscle
2. Right 'Posterior Thigh Muscles'(Biceps Femoris and Semitendinosus/Semimembranosus)
So now I am confused because it seems, from the the above video , that large left and right leg muscles are being used decelerate pelvis motion rather than assist in its rotation. Have I interpreted this correctly or have I gone wrong somewhere?
Regards
DB