Variable Muscle Control

[Guest guest]

In previous articles in which I have discussed the shortcomings of theories

of muscle activation, core stabilisation, abdominal muscle control and trunk

strengthening, I have stressed that the same movement pattern or trajectory

of external movement may be produced by different patterns of muscle

involvement. This, of course, contradicts some of the hypotheses which

various therapists have made in relying on static muscle testing and muscle

training to correct for so-called " muscle imbalances " .

The consequences of research, such as that appearing in the following

article, have profound implications for anyone who is promoting ideas of

standard, very precisely reproducible patterns of training the muscles to

carry out various " functional " tasks. After all, how can one prescribe

specific set ways of recruiting muscles in any complex natural movement if

research now shows that these highly deterministic patterns of muscle action

are not characteristic of human movement?

The author of this article, by the way, is one of the most respected

international scientists working in the field of motor control today. I

wonder what the opinion of the determinists is on this issue?

Gottlieb GL Minimizing stress is not enough. Motor Control 2000 Jan; 4(1):

64-7

<Muscle stress is plainly one of the physical variables that the central

nervous system probably wishes to minimize. This criterion does not uniquely

define the patterns of muscle activation. It fails to explain the degree of

coactivation of muscle antagonists that is widely found, and it cannot

explain why two movements or movement segments that follow an identical

trajectory driven by identical joint torques can be driven by different

patterns of muscle activation. Muscle contraction provides for both net

joint torque and limb stability. The minimization of the sum of muscle

stresses, raised to any power, is an insufficient rule.>

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Dr Mel C Siff

Denver, USA