Auteur : [[Leslie Kaminoff]] MOC : [[YOGA]] - [[ANATOMIE]] Source : [[3 GARDEN/Notes/Yoga Anatomy]] Date : 202302021322 *** ## Les types de contractions musculaires The words concentric, eccentric, and isometric are used to describe muscle actions (figure 3.5). These terms actually describe the effects of the relationship between your muscle and the resistance it meets. - In a **concentric contraction**, your muscle fibers contract and generate more force than the resistance that is present. This causes the ends of your muscle to slide toward each other, and the muscle shortens. - In an **eccentric contraction**, your muscle fibers contract and generate less force than the resistance that is present so that the ends of your muscle slide apart, and your muscle lengthens. Your muscle is active as it lengthens, so this is not the same as relaxing your muscle. ([Location 834](https://readwise.io/to_kindle?action=open&asin=B0998616FH&location=834)) - In an **isometric contraction**, your muscle fibers contract and generate the same amount of force as the resistance that is present so that the ends of your muscle neither move apart nor move together, and the length of your muscle does not change. ([Location 843](https://readwise.io/to_kindle?action=open&asin=B0998616FH&location=843)) CEPENDANT : - **Muscles pull, they don’t push.**   In a concentric contraction, the pulling power of your muscle is greater than the resistance. In an eccentric contraction, the pulling power of your muscle is less than the resistance. In an isometric contraction, the pulling power of your muscle is exactly the same as the resistance. In all of these cases the muscle is firing, and the molecules in your myofibrils are ratcheting together to pull. Your muscle is never actively pushing the fibers in a way that slides them apart—that happens because the resistance is greater than the pulling force being generated. So, how is it that we can push something away? Any joint movement includes a part that is lengthening and a part that is shortening. Whether or not your joint is flexing, extending, or rotating, some muscles are lengthening and some are shortening. Your shortening muscles are concentrically contracting; your lengthening muscles are in various degrees of relaxation or are eccentrically contracting. ([Location 1029](https://readwise.io/to_kindle?action=open&asin=B0998616FH&location=1029))