This posting which I made to another group may be on interest here.
On 3/20/99, JIM wrote:
<<Cruising aroung on the net I came across a site called Backaid
www.backaid.com/index) and the owner .... speaks about a machine designed by
good ole' Arthur Jones. Supposedly the machine, through three different
sessions, helps to define strength, endurance, and any discrepancies in the
musculature/lumbar composition to identify problems. Granted that is a very
brief description and the results are based off the administrators tests, but
what I am curious is if anyone has heard of this or used/tried this type of
therapy?>>
***The entire concept of machine testing is complicated and involves several
issues besides mere evaluation of injuries and strength.
THE ISOLATION MYTH & TESTING
The MedX machines, devised by Arthur Jones as his commercial counter to the
'Cybex', 'KinCom' and other financially successful joint torque testing
devices, are reasonably well known. However, like all of these machines, they
are based on an isolationist philosophy of single joint testing at a time,
which bears little or no relationship at all to what happens in real sporting
movement.
Virtually the only place where one tries to isolate single joints is in
bodybuilding, but, in general, all sporting movement involves many joints in
complex interactions of flexion, extension, adduction, abdution, rotation ans
so forth. Increasing numbers of scientific and clinical articles are now
emerging which question the validity of using machine testing to identify
strengths and weaknesses in human movement.
THE POLITICS OF MACHINE TESTING
To understand the popularity of computerised and other testing machines, one
must understand the structure of medical insurance and academic research. In
many medical claims, legal liability is on a much more solid foundation if one
can produce impressive figures which appear to give precise details of the
human body. Production of the most convincing sets of graphically and
mathematically analysed data wins cases and makes money for someone.
Similarly, medical and sporting research using such machines as a sort of
universal 'Rolls Royce' standard can create numerous publications, attract big
sponsorships, increase departmental size and enhance university reputations.
One again, a money and status motive emerges. This is not to say that machine
research is all contrived and useless; it is not. However, in many cases, far
cheaper means of research, including the use of free weights, field tests and
relatively inexpensive tests with existing university engineering apparatus,
are possible - but the successful marketing of such devices has created an
aura of mystique and quality perfection about them and research which uses
other means does not seem to carry the same weight.
FALSE CLAIMS
For many years we have seen claims that muscle injuries are due to subtle or
gross imbalances between certain muscles and that machines can measure these
imbalances by assuming that one can analyse one joint at a time and then
magically summate them to yield an overall picture of an entire limb or body
in action in a given sport.
Thus, we heard, if one did not have a ratio of 60:40 quad to hamstring
strength ratio, that one was far more likely to suffer injuries such as
'pulled' hamstrings. Moreover, if a machine showed that one limb was a few
percent 'weaker' than the other limb, then that would set the stage for
injury. Not too many years after these figures were bandied about with
authoritative abandon, clinical research began to show that there appeared to
be no such correlation between the incidence of injuries and so-called
imbalances measured on isokinetic and related machines.
'Agonist-antagonist' muscle strength ratios vary with speed of movement, type
of movement, joint angle and several other factors which show that machine
testing often bears little or no relationship to human performance or the
genesis of injuries.
THE BACK & ISOLATION
<<. . . . was wondering if you could isolate just the lumbar area and then
actually measure these type of things? >>
The important point here is to ask if it is desirable, useful and safe to try
to isolate the lumbar area. First of all, the idea of isolation really
applies to a single joint and, since all of the spine, including the lumbar
spine, is a complex interacting series of articulations (joints), isolation of
the lumbar spine is scientifically and practically misleading.
In fact, any actions which tend to isolate and create asymmetric loading of
specific spinal joints and the discs within them are known to cause damage to
the spine, so the very idea of stress testing (under maximal conditions)
isolated parts of the spine is illogical and potentially risky.
PERSONAL EXPERIENCE
Some years ago, a group of us were subjected to MedX spinal testing and the
marketing clinicians involved emphasised the 'value' of being able to clamp
the thighs firmly down to the seat to prevent any motion other than that of
'the lumbar spine'. Our role was to perform lumbar extension exercise so as
to produce as large as possible a force from our back muscles.
As a competitive lifter of many years' standing, I have never experienced my
lumbar spine feeling so vulnerable and helpless as in that highly unnatural
force-producing manoeuvre. All the time while I was being tested, my research
and lifting training kept reminding me that this sort of isolationist force
production by the body is NOT the way which is most efficient, productive or
safe. My head was filled with equations proving biomechanically that such
testing is inefficient and potentially unsafe, as well as recalling all the
years of technical training to clean, snatch or deadlift which taught me never
to rely entirely on the lumbar spine for any of those lifts.
After that testing, which told me absolutely nothing more about my spine and
trunk than I did not already know from my competitive career, I felt more
relief than I had enjoyed ever in saving a tedious competition lift from
failure! At least I was a scientific guinea pig and I did not have to pay for
that lumbar (and other joint) tests.
Those who administered the tests didn't think it too relevant that anyone
lifting weights competitively or handling loads in manual labour does NOT rely
on isolated lumbar action, but on use of many joints and muscles of the back
AND legs. Nor did they seem unduly concerned about the relative influence of
reduced flexibility in any joints, idiosyncrasies of proprioceptive
capabilities, or inappropriate neuromotor patterns in contributing to injury.
Interestingly, machine testing of my knee joint showed that my injured knee
(chronic chondromalacia patellae or wearing away of the cartilage behind my
knee cap) actually was producing greater torque than my healthy knee - exactly
the opposite of what the medics believe - none of the clinicians or scientists
could satisfactorily explain this. During some of our own joint testing, I
came across the same phenomenon in other athletes, so that produced further
evidence that machine testing based on simplistic notions of 'muscle balance'
may well be seriously flawed. On the other hand, simple stepping and walking
tests using the same subjects on a force plate and with high speed video
correctly identified the 'weaker' limb.
AND SO?
The bottom line is that, if one wishes for some very specific reason, to test
an isolated joint at a certain speed and over a certain range, then by all
means do so, but do not make any unwarranted extrapolations from that sort of
isolated testing to make any deductions about the efficiency and safety of an
entire movement. Generally, isolationist machine testing tends to be very
uninformative in identifying the causes of musculoskeletal pain or injury,
especially in complex sporting or workplace situations.
It has never been shown that machine rehabilitation (with MedX, Cybex or what
you will) has ever been more successful than free standing, PNF, free weight
or electrostimulation (or other physical therapy modalities) rehabilitation.
Anyone who makes any claims to the contrary is misleading or inadequately
informed. In fact, many physical and other therapists have achieved at least
equal success with use of the hands alone in carrying out various
mobilisations, pressure point techniques, trigger point releases, manual
resisted movements (as in PNF) and graded exercises without machines.
Dr Mel C Siff
Denver, USA
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