Hellstrom, J. and Tinmark, F. (2008) The Association Between Stability and Swing Kinematics of Skilled High School Golfers. In Crews. D. and Lutz, R. (Eds.) Science & Golf 5. Proceedings of the World Scientific Congress of Golf.
This study looked at the association between stability of 11 male golfers (age 17±1 years, height 1.80±0.05m, body mass 70±6kg and handicap 0.4±1.8) and 7 female golfers (age16±1 years, height 1.64±0.07, body mass 59±11 and handicap 3.4±2.1) with swing kinematics.
Four stability tests were used, including ‘supine hip extension’, ‘one-legged squat’, ‘sitting hip flexion’ and ‘prone bridge’ and 3D golf swing kinematics was collected using a Pohlemus Liberty Electromagnetic Tracking System.
Kinematics which were assessed include pelvic sway and upper body sway (lateral movement), pelvic thrust and upper body thrust (forwards and backwards) and pelvic lift and upper torso lift (up and down movement). Pelvic rotation, upper torso rotation and pelvic-torso separation (aka x-factor) were also tested.
Upper body sway (backswing) correlated with the prone bridge stability test (r=0.64) and one legged squat (r=0.53). Pelvic rotation (top of backswing) correlated with supine hip extension (r=0.51) and one legged squat (r=0.67). Upper torso rotation also correlated with the supine hip extension (r=0.49) and one legged squat (r=0.67).
I like the idea of this study, because it is one of few studies that have correlated physical fitness attributes with golf swing kinematics (compared to club head speed or driving distance). There are a few things however, which I believe, make the study a little bit weak.
Firstly, I think the scoring criteria (0-4 scale) for the stability tests could have something to do with the limited correlational results. There was no reliability data given for the testing, yet “an experienced physiotherapist” conducted all the stability assessments. The tests are subjective and given then a score. No validity of this scoring system is mentioned.
There was no clear definition of ‘stability’. If it’s simply the ability to withstand unwanted movement, then the 4 stability tests used within this study sound pretty fair to me. However, without a clear definition of stability we don’t know what exactly they want to test.
It is mentioned, however, that both active and passive stability are needed. The tests used in the study might be great for general populations yet are they specific enough for golf? They recommend that more specific stability test are used (in a transverse plane and at higher speeds). But what about stability tests under heavier load too (as a test for the active stability anyway). After all, the golf swing does put a great deal of force on the body (so this would still be more specific than standing on one leg, or laying on the floor!).
For me, it comes back to the tests and scoring criteria. These current tests within this study are great, but there definitely needs to be some better progressions. Whether that’s under more load, or in a transverse or frontal plane and at higher speeds. This might have generated better correlative results.
How did they define what amount of sway, thrust and lift was allowed for these high school golfers? The study doesn’t mention how much thrust, sway and lift is normal or allowed for this population being tested. Is there normative data for this population? This lack of information and questionable validity of their kinematic analysis makes it difficult to know what was being tested, the reliability of results found and makes the study difficult to replicate.
I agree with their explanation for the association between the prone bridge and upper body sway; the prone bridge offers good stability required to control upper body sway. Little explanation was given for the (slightly weaker) correlation between the one legged squat and upper body sway. Even though the correlation is relatively weak, yet the one legged squat does require core/trunk stability, which could be required to minimise upper body sway (in my opinion).
The one legged squat was significantly correlated to pelvic rotation and upper torso rotation in the backswing. So too was the supine hip extension test, but with a slightly weaker correlation.
A rationale was not given, yet I believe loading into the trail side leg, without over rotating the pelvis, requires stability in that trail side hip, just like what’s tested in the one legged squat. It would be interesting to see if the one legged squat of the trail side leg would have a stronger correlation compared to only looking at both legs together.
The results were not broken down into the males and females, which could have given some different results or at least some insight into gender differences. This might have been due to the small sample size and that there was lots of data already.
Finally, the warm up approach seemed at little Laissez faire, with 10 minutes of hitting golf balls. The participants in this study were good very good amateur golfers, yet the warm up each of them took could have effected their kinematics on the day, leading to less reliable results.
The validity and reliability of this study is questionable. I think using the scoring criteria for the stability tests didn’t help find more (and stronger) correlations. And not showing normative data for the sway, thrust and lift for this population brings their kinematic analysis into question.
There was a lack of a clear rationale and explanation behind some of the findings and results. Apart from the recommendation to use stability tests which are more golf specific. But I’m not convinced this is the answer!
I think it would be exciting to see more research done looking at the association between golf swing kinematics and physical fitness attributes. From all the tests performed, this paper supports the use of the one legged squat as a good test of stability for golfers.
To read Hellstrom and Tinmark’s paper, click HERE. It’s available online for free.