Physiology of Stretching
Stretching is helpful in the aspect that it helps to improve flexibility, athletic performance, and reduces the risk of injury during physical activity. It is also helpful in the process of realigning tissue inside of muscle fibers (Lynn Hetzler). The stretching itself, however, is actually a complicated process.
A muscle is composed of numerous strands of tissue, referred to as fascicles. Each one of these fascicles are made up of bundles of muscle fibers (Lynn Hetzler). The muscle fibers are then made up of tens of thousands of myofibrils. Myofibrils are thread-like structures that are able to contract, relax, and stretch. Sacromeres, which are millions of thick and thin myofilaments laid end-to-end, overlapping. This causes muscles contraction, which in turn, causes an increase in myofilament overlap. In contrast, relaxing a muscle causes a decrease in myofilament overlap. When there is a decrease in myofilament overlap, the muscle fibers are allowed to elongate. This is the point where sarcomeres are at their maximum length (Lynn Hetzler). If any additional stretching occurs, the tension is applied to the ligaments (which connect the muscle to the bone).
In muscles, there are things called proprioceptors. Proprioceptors are nerve endings that relay all the information about the musculoskeletal system to the Central Nervous System (Rebecca Booth B.A.). Stretch receptors are the major proprioceptors in the muscle, with the major stretch receptor of the muscles being called muscle spindles. The proprioceptors that are located in the tendons are called golgi tendon organs.
Proprioceptors are important components of the body’s stretch reflexes, which are built-in safety mechanisms that prevent us from injuring our muscles and joints (canadianfitnessonline.net). There are two major stretch reflexes, the myotatic stretch reflex and the inverse mytotatic...