Agonists and Antagonists – How we move
We move everyday and barely think about how it happens.
Even when we are exercising and moving our body intentionally, we still rarely think about how it happens.
We use our muscles right?
Well there is a little more to it.
Our muscles actually have 3 actions:
Concentric action - When a muscle shortens.
Eccentric action - When a muscle lengthens.
Isometric action - No length change as the muscle contracts (think of doing a plank).[i]
When we move we often think about the muscle that is contracting to make us move.
For example, when we bend at our elbow, we think about our using our bicep.
However, we don’t think about the muscles on the other side lengthening.
Muscles can only pull and cannot push so they must work in pairs.[ii]
Agonist
This is the main muscle that cause the movement.[iii]
Antagonist
This is the muscle that opposes the movement that lengthens as we do the movement.[iv]
Synergist
These are the other muscles that help out.
They often stabilise the joint.
They often jump in when the agonist gets tired which can cause issues.[v]
Conclusion
Muscles can only pull not push so therefore must work in pairs. While one contracts (agonist), the other lengthens (antagonist). Meanwhile others help the agonist (synergists). By knowing which muscles are do which roles we can look for imbalances and know when synergists have taken over and are causing issues.
[i] https://www.acefitness.org/fitness-certifications/ace-answers/exam-preparation-blog/3580/muscles-in-motion/
[ii] https://www.bbc.co.uk/bitesize/guides/zct2hv4/revision/2
[iii] https://www.acefitness.org/fitness-certifications/ace-answers/exam-preparation-blog/3580/muscles-in-motion/
[iv] https://www.acefitness.org/fitness-certifications/ace-answers/exam-preparation-blog/3580/muscles-in-motion/
[v] https://www.acefitness.org/fitness-certifications/ace-answers/exam-preparation-blog/3580/muscles-in-motion/
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