What Happens When We Stretch Our Muscles?
The stretching of a muscle fiber begins with the sarcomere, the basic unit of contraction in the muscle fiber.
- As the sarcomere contracts, the area of overlap between the thick and thin myofilaments increases.
- As it stretches, this area of overlap decreases, allowing the muscle fiber to elongate.
- Once the muscle fiber is at its maximum resting length (all the sarcomeres are fully stretched), additional stretching places force on the surrounding connective tissue.
- As the tension increases, the collagen fibers in the connective tissue align themselves along the same line of force as the tension.
Hence when you stretch, the muscle fiber is pulled out to its full length sarcomere by sarcomere, and then the connective tissue takes up the remaining slack. When this occurs, it helps to realign any disorganized fibers in the direction of the tension.
This realignment is what helps to rehabilitate scarred tissue back to health.
When a muscle is stretched, some of its fibers lengthen, but other fibers may remain at rest.
The current length of the entire muscle depends upon the number of stretched fibers (similar to the way that the total strength of a contracting muscle depends on the number of recruited fibers contracting).
The more fibers that are stretched, the greater the length developed by the stretched muscle.