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46-4 Types of Muscle Action - Coggle Diagram
46-4
Types of Muscle Action
Muscle action or contractions are
described as
Isometric contraction
constant length
Both the distal and proximal bony levers are fixed
No visible motion occurs
when the muscle develops active tension
Sarcomere does not change length
Eg: Holding the weight without changing
the joint angle
Dynamic contractions
Concentric contractions
shortening of
muscle under load
Muscle shortens while continuing
to produce active tension
Sarcomere shortens
Cross-bridges are formed,
broken
and reformed
Bones move closer together
Described as Positive work
Eccentric contractions
lengthening of
muscles under load
Muscle elongates while
continuing to produce active tension
Sarcomere lengthens
Cross bridges are broken,
reformed
and broken again
Load is greater than the
force of the sarcomere
Bones move away from each other
Described as Negative work
Same as what's happening at sarcomere
level depending on the force applied
When muscles fiber is activated,
cross
bridges forms
Either
constant length,
shorten or
lengthen