Lombard's Paradox

[Guest guest]

Dr Siff,

I have been studying the theories behind reciprocal inhibition and

synergistic dominance and their effects upon postural distortion patterns.

During my research I came across an article on cycling performance which

mentioned Lombard's paradox - where agonist/antagonist are in concurrent

concentric contraction (theoretically this should 'cancel out' movement!). An

example is the quadriceps contracting to extend the knee and the hamstrings

contracting to assist in hip extension during cycling, running or squatting.

I am guessing that this is possible due to the fact that the muscles are

acting upon separate joints, but have been unable to find text anywhere to

expand upon the concept.

Can you or any of our other Supertrainers help me out on this one?

Dax Moy

London

England

[Mel Siff: From Ch 3 of " Supertraining " :

In work derived from Lombard's Paradox ('Antagonist muscles can act in the same

contraction mode

as their agonists'), s (1985, 1987) found that the rectus femoris of the

quadriceps and all the

hamstrings act in three different ways during cycling, emphasizing that

biarticular muscles are considered

enigmatic. This paradox originally became apparent when it was noticed that in

actions such as cycling

and squatting, extension of the knee and the hip occurs simultaneously, so that

the quadriceps and hamstrings

are both operating concentrically at the same time. Theoretically, according to

the concept of concurrent

muscle antagonism, the hamstrings should contract eccentrically while the

quadriceps are contracting

concentrically, and vice versa, since they are regarded as opposing muscles.

Others have shown that a muscle which is capable of carrying out several

different joint actions, does not

necessarily do so in every movement (s, 1982, 1985). For instance,

gluteus maximus, which can

extend and abduct the hip, will not necessarily accelerate the hip

simultaneously into extension and abduction,

but its extensor torque may even accelerate the hip into adduction (Mansour &

Pereira, 1987).

Gastrocnemius, which is generally recognised as a flexor of the knee and an

extensor of the ankle,

actually can carry out the following complex tasks (see Fig 3.48):

(a) flex the knee and extend the ankle; ( flex the knee and flex the ankle;

© extend the knee and

extend the ankle.

These are some of the reasons why one should not rely on simplistic isolated

muscle testing under

non-sporting clinical conditions, as is the case with anyone who rigidly applies

muscle testing

methods by workers such as Kendall and Janda. ]