Why do we grunt and make faces when lifting something heavy?
In: 5
When you want to lift something heavy, you need a firm base for the muscle that is doing the work to be grounded on. Say you are picking up a heavy box. The muscles that are doing the work are you glutes (butt), hamstrings (back of thigh), and quads (front of thigh) mainly. But if those muscles all pushed alone, your torso would fold and the box wouldn’t move. Think about trying to pick up a heavy weight that’s at the end of a pool noodle.
Now to prevent that, you have to tense up your core muscles. When you do this, it’s gonna want to squeeze the air out of your lungs when your abs contract. You can close your airway to prevent this. Now you have the air inside you being squeezed. When any escapes it’s gonna sound like a grunt. Having your torso tensed up like that turns your pool noodle body into a more rigid lever that your muscles we discussed before can use to lift the box.
In short, the grunt is because you are squeezing and holding air inside you as you brace for the lift.
Edit:
I didn’t say anything about making faces. I don’t know of any official sciencey explanations for this but I have a guess. When you tense up your body for the lift, it increases your blood pressure A LOT. This causes blood to push up into your head which turns you red and is uncomfortable. You can resist this by tensing muscles in your face and neck as well. The muscles squeezing makes it a little harder for blood to rush in. This is something we unconsciously learn to do when straining and the side effect is funny faces.
You can watch YouTube videos of world class weightlifters bleeding out of their noses and eyes when breaking records. This is because their blood pressure gets so high from the effort that it ruptures the fragile blood vessels in the face. Again, tensing the face and neck can help reduce the rush of blood from elsewhere into the face.
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