Enhancing your rotator cuff muscle performance involves understanding how your cuff muscles work. What exactly happens during rotator cuff exercise and rotator cuff rehab. Have you ever wondered what is going on inside the muscles of rotator cuff when you are doing some rotator cuff training?
The basic action of any muscle is contracting; indeed all that any muscle can do is create contracting force. For example, when you think about moving your arm using your biceps muscle, your brain sends a signal down a nerve cell telling your biceps muscle to contract.
The amount of force that the muscle creates variies; the muscle can either contract a little or a lot depending on the signal that the nerve sends. That is why skeletal muscles are said to be under conscious control.
How does a muscle contract?
A muscle is actually a bundle of many cells called fibers. You can think of muscle fibers as long cylinders, and compared to other cells in your body, muscle fibers are quite big.
A muscle fiber contains many myofibrils. Myofibrils are cylinders of muscle proteins. These proteins allow a muscle cell to contract. Myofibrils contain two types of filaments that run along the long axis of the muscle fiber, and these filaments are arranged in hexagonal patterns. There are both thick and thin filaments present in each skeletal muscle. Each thick filament is surrounded by six thin filaments.
Thick and thin filaments are attached to another structure called the Z-line. The Z-line runs perpendicular to the long axis of the fiber. The myofibril that extends from one Z-line to another is called a sarcomere. It is the thick and thin filaments do the actual work of a muscle; and the way they do this is pretty cool.
Thick filaments are made of a protein called myosin. At the molecular level, a thick filament is a shaft of myosin molecules arranged in a cylinder. Thin filaments are made of another protein called actin. The thin filaments look like two strands of pearls twisted around each other.
During muscle contraction, the myosin thick filaments grab on to the actin thin filaments by forming what are known as crossbridges. The thick filaments pull the thin filaments past them, making the sarcomere shorter. This shortening of the sacromere results in the shortening or contracting of the whole muscle.
Types of rotator cuff muscle contractions
There are two distinct types of muscle contracting; Isotonic and Isometric. The contracting or shortening of the muscle fibers creates a mechanical force, or muscle tension that affects muscle performance.
Whether the muscle itself changes length, which is known as same-force or isotonic contraction, or not, which is known as same-length or isometric contractions depends upon what we want the muscle to do.
For example, when the bicep muscle contracts, it shortens and pulls the ulna up towards the shoulder blade. This movement allows you to lift your forearm and any given load – Isotonic contraction.
In contrast, if you are carrying a really heavy load, such as a full suitcase, that makes you unable to lift your forearm, then the biceps does not shorten significantly. But the force generated by the muscle is still helping you carry the suitcase – Isometric contraction.
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