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Let's talk about isotonic versus isometric contraction .
Uh When you learn a new language , it's so easy to get really confused .
Isotonic versus isometric isotonic gives you a real little hint in there .
It has the word tonic or tone in there .
When we talk about contractions , it's all about the muscle moving .
When we look at isotonic contraction , there's actually two kinds of contractions underneath .
There's an eccentric contraction and a concentric contraction , concentric contraction is what we use all the time when we're at the gym .
So let's take biceps brachii as our classic example .
I want you to feel it .
It's this muscle here .
A lot of times we do bicep curls there .
It is .
Its origin is on the super glenoid tubercle and the cor coid process , its insertion is the radial tuberosity on the radius .
When you feel that muscle belly and we get those muscle fibers to shorten and that's its job .
Its action is flexion of the elbow when we get it to shorten and you feel a bunch up underneath there , that's concentric contraction , concentric contraction , shortening of the muscle fibers .
Now let's go in the opposite direction .
It's working while those muscle fibers are getting longer and lengthening .
So when we look at isotonic contraction , we have concentric contraction and still working .
The muscle is still working .
We have centric contraction .
Now , when we think about isometric contraction , this is where you can take a cup of water , watch the joint angle .
It's gonna stay the same biceps still engaged .
And if I start to fill up that water , I'm gonna fill it up right to the top .
Is my muscle still working ?
Absolutely .
It's still working .
The muscle is contracting joint angles not changing .
So we see this all the time in yoga actually where you hold a pose and then the muscle fatigues because it's working for a long period of time .
So , isometric contraction is more muscle work applied more load , but no joint change under isotonic concentric contraction and eccentric contraction under isometric , maintaining joint angle , but increasing the workload .