How are we able to flex muscles without moving the associated limb?
In: 20
Muscles often come in push-pull pairs. If you flex both at the same time, the appendage won’t move.
Edit: Push-pull from an external perspective. u/aprilflowers75 reminds me muscles can only pull.
Muscles are not “all flex or no flex” structures. There’s a near-infinite level of contraction. One can flex with just enough force for the entire muscle to become tense, but not enough force to move the limb/appendage. These are called “Isometric Contractions.”
Flex your bicep and feel the muscle with your hand. Now feel your tricep while still flexing. Your tricep is flexing because its keeping your limb in place because you’re flexing your bicep. The two muscles work together.
Can we do this?
Been flexing a bit for the last minute and whatever I flex, the limb moves at least a little bit.
Muscles generally come in pairs, especially for limbs, bicep/tricep, for instance. When you flex one, the opposite muscle pulls at the same time, to keep the limb still.
Muscles can only pull. If you relax one, the other one pulls the limb in the direction of that muscle. So if you relax your bicep, your tricep pulls the forearm back, at the elbow.
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