The controversial subject of isolated muscle testing arises regularly and is
regarded with undeserved acclaim by some. Unfortunately, these tests, often
relying on a wondrous array of ingenious toys and technology, are sometimes
performed as if the muscles and joints act independently of the nervous
system. It is well known that posture and balance are the result of
structure and function, and that muscle 'weakness' may have far more to do
with underlying nervous processes than intrinsic muscular insufficiency.
Let us consider some basic questions regarding isolated muscle tests, whether
performed manually or by the use of various technological devices:
1. What do these tests reveal on a person who is under general anaesthesia?
2. What does passive movement of a limb tell the tester under such
conditions?
3. Do the muscles reveal the same 'imbalances' for deviations of a few
degrees from the prescribed test positions?
4. Do these tests reveal the same 'imbalances' if we perform selective bloc
ks at different levels of the spinal nerves by injecting local anaesthetic?
5. Do these tests reveal the same 'imbalances' if an adjacent joint is
flexed, extended, adducted or abducted?
6. Do these tests reveal the same information if the test is carried out
with slow, fast and ballistic muscle action?
7. Do the same 'imbalances' occur when the entire limb or body is carrying
out a complex sporting skill?
8. Do the tests reveal the same 'imbalance' if the patient perceives any
part of the movement to be painful?
9. Do these tests reveal the same imbalances if the stretch reflex is
strongly elicited during any stage of the movement?
10. Do these tests take into account any learning effect which may distort
the results?
11. Do these tests totally eliminate the possible effects of fatigue,
especially subjects whose static strength-endurance is already compromised?
12. Do these tests reveal imbalances which may become significant only when
maximal force, maximal endurance or maximal range of movement occurs?
13. Do these tests distinguish between muscle weakness and neurological
dysfunction?
14. Do these tests distinguish between central and peripheral nervous
factors which may underlie the muscle 'imbalance'?
15. Do these tests make allowance for the existence of conditioned reflexes
(operant and respondent conditioning of muscle actions) which influence the
pattern of muscle movement?
16. Do biomechanical tests always agree with the apparent results of muscle
tests?
17. Do these tests explain why athletes with apparently clear evidence of
'imbalance' often are able to effectively and safely produce exceptional
performances?
18. Do these tests always display high levels of reliability, repeatability
and accuracy?
19. Do the identical muscles always become involved in the same way during
every repetition of the test?
20. Do the tests take into account the fact that different muscular
contributions may produce the same joint action, especially in complex
multi-articular movements?
21. Do the results of isolated muscle tests correlate strongly with tests of
complete sporting actions?
22. Do these tests distinguish between the many different types of
'strength' fitness, such as starting-strength, acceleration-strength, maximal
strength, maximal power, rate of force development (RFD), deceleration
strength and eccentric strength?
If one ponders all of these questions in the light of current biomechanical
research and clinical findings (e.g. in various issues of Exercise & Sports
Sciences Reviews & the Journal of Biomechanics) , it will be noted that the
answers to the last 20 yes-no questions is no. This offers some pretty sound
reasons for seriously questioning those old traditional tests.
Isolation tests may certainly have value in limited clinical or pathological
situations. If some muscle is ruptured in a linked system, there is no doubt
that isolating which muscle is damaged is entirely relevant. However, if no
such trauma is evident from pain, swelling or severe disruption of movement,
the use of isolation testing simply because one suspects 'muscle' weakness or
'imbalance' in an athlete, becomes a less definitive tool.
Even though such isolationist tests may identify which component in a linked
chain may be implicated in some neuromuscular pathology, it will not
necessarily give definitive information about what may be happening in actual
complex movements or where the joint acceleration has nothing to do with the
muscle being tested.
It is well known that torque or acceleration about a joint may be due to the
action of a muscle which does not span the joint concerned or even serve as a
classical 'prime' mover, assistant mover, etc. (e.g. Zajac F & Gordon M
Determining muscle's force and action in multi-articular movement Exerc
Sport Sci Revs 1989, 17: 187-230).
It really is time that more definitive tests were developed and that the
shortcomings of the older tests stimulated more research into their revision.
The old ones may play a limited and useful role in cases where isolation of
a single joint clearly is involved in a clinical condition, but they do not
necessarily extrapolate at all well to the realm of multi-dimensional sport.
What is the alternative? Evaluation of the sporting actions themselves (and
partial lifting exercises), performed at increasingly more demanding levels
of stress is one such method.
References
Siff M C (2003) Facts & Fallacies of Fitness
Siff M C (2003) Supertraining
Supertraining Forum Archives: http://groups.yahoo.com/group/Supertraining/
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Dr Mel C Siff
Denver, USA
http://groups.yahoo.com/group/Supertraining/ (Sports Science and Rehab Forum)
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