Lamalam
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Why when holding steady both flexor and extensor contracts ? Arent they a pair of antagonistics muscle? One contracts one should relax isnt [email protected]@

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mo_masquerade
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How weird. I was just looking over this paper. Yes they should both be contracted when holding steady as antagonistic pairs of muscles are only needed when moving a joint. So if it is being held steady, neither is flexed and both are contracted. I hope this makes sense.
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zedeneye1
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to make sure arm doesn't move the other way (to save from upward motion). That's for a "tight" steady. A simple steady/raise only needs one side muscle.

Like when holding a bag, you use one side. But while holding a pistol/rifle you might be using both muscles to make sure the gun stays pointed exactly on target , no downward movement and no upwards movement.
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Dynamo123
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(Original post by Lamalam)
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Why when holding steady both flexor and extensor contracts ? Arent they a pair of antagonistics muscle? One contracts one should relax isnt [email protected]@

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It is known as co-contraction, and helps to steady or stabilize.
In technical terms, there are two types of contraction: concentric, also called shortening contraction, and eccentric, in which the length actually increases during contraction.
When both muscle pairs contract together, one contracts concentrically, and the other eccentrically.
This is what happens when you are lifting a load and trying to hold it steady.

While the definition "if one is contracting, the other must relax" is sufficient at A2 level, it isn't actually accurate.
If you need more details ask away
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Lamalam
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(Original post by Dynamo123)
It is known as co-contraction, and helps to steady or stabilize.
In technical terms, there are two types of contraction: concentric, also called shortening contraction, and eccentric, in which the length actually increases during contraction.
When both muscle pairs contract together, one contracts concentrically, and the other eccentrically.
This is what happens when you are lifting a load and trying to hold it steady.

While the definition "if one is contracting, the other must relax" is sufficient at A2 level, it isn't actually accurate.
If you need more details ask away
thanks
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