These extracts from a discussion which I had with a student who contacted me 
recently may be of interest to this group.

<< Dear Dr Siff,   After reading that collection of references you sent on 
LIFTING REVISITED, I thought that you might be interested in the latest Chek 
Institute videos, especially this one:

> Understanding Force Couple Relationships

-Understand the spino-scapular/gleno-humeral force couple mechanism
-Learn how to identify force couples in the sagittal, frontal and transverse 
planes
-Understand lumbo-pelvic rhythm >

It seems that the Chek guys still didn't get it when you and some others 
pointed out that their concept of a force couple is incorrect and 
unscientific.  They also seem to preach that old PT lumbo-pelvic rythm that I 
think was popularized by Calliet, even though I think you said  this rhythm 
also involves the knee joint because it is crossed by muscles that cross the 
hips and knee joints.>

***Thank you, that was most interesting - after all that discussion that we 
had some months ago on forces and couples, I am surprised that this 
deficiency in their teaching material was not revised.  

Yes, it was probably R Cailliet ('Low Back Pain Syndrome'  pp44-49) who 
popularised the lumbar-pelvic lifting rhythm.  Although he used the term 
"lumbar-pelvic rhythm", his discussion certainly involved the action of the 
knee flexors and extensors.   He wrote:

"One of the mechanical advantages of flexing the hips and knees is that it 
places the hip extensors at a mechanical advantage.  Another advantage is 
that the quadriceps femoris group assists in the lifting and simultaneously 
tenses the iliotibial band which is the site of attachment of the glutei."

In other words, Cailliet did recognise the role of the knee linkage system in 
lifting, but he chose to retain the term "lumbar-pelvic rhythm", possibly 
because he was more interested in only the trunk aspect of lifting.  Of 
course, since the gastrocs and soleus both cross the knee joint, they also 
play an important role in the overall lifting sequence, a fact that is 
stressed in several biomechanics articles on functional sporting movement.  

If one uses the "double knee-bend" technique, or more correctly tries to 
accentuate its use, then the role of soleus and gastrocs become even more 
important, though Cailliet showed no clear awareness of the various methods 
of lifting used by the different types of competitive lifter.

If we bear carefully in mind that Cailliet was focusing on only one aspect of 
the lifting chain of events, we may be justified in talking about the 
"lumbar-pelvic rhythm" as one of several other related rhythms involved in 
the process of lifting.  However, it is incorrect and misleading to regard 
the "lumbar-pelvic rhythm" as the only or most important aspect of efficient 
and safe lifting.  

As some of those studies showed, there is no compelling evidence that stoop 
lifting is associated with a higher incidence of spinal pain and dysfunction 
than squat lifting.  In fact, it is not uncommon to observe some extremely 
strong Powerlifters using a more stooped style of deadlifting for years 
without spinal damage.

The papers that I summarised in my post on "Lifting Revisited" strongly 
suggested that there is no single correct or safe rhythm, but a number of 
different rhythms which take place during squat type lifting and stoop 
lifting, as well as between Olympic-type lifting that intentionally 
exaggerates the "double knee bend" technique, and Powerlifting-type lifting 
that forbids one to rebend the knees at any stage of the deadlift.  Clearly, 
the Chek group was unaware of these findings at their time of production.  

Russian studies have shown (published in the 'Lehrbeilage Gewichtheben' 
weightlfiting manuals from Germany) too, that lifting posture is strongly 
determined by the relative ratios of lengths of leg and thigh, arm length and 
torso length and other such kinanthropometric measures.

Once again it is apparent that many popularised solutions to the back pain 
and disability issue still tend to be simplistic and limited, but I have no 
doubt that most omissions eventually will be rectified when scientists and 
clinicians begin to appreciate more widely that all forms of competitive 
lifting (including "Strong Man' contests and Highland Games) offer a natural 
laboratory with a wealth of practical information for the general public.

Mel Siff

Dr Mel C Siff
Denver, USA
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