Stretching

Stretching is a form of physical exercise in which a specific muscle or tendon (or muscle group) is deliberately expanded and flexed in order to improve the muscle's felt elasticity and achieve comfortable muscle tone.^[1] The result is a feeling of increased muscle control, flexibility, and range of motion. Stretching is also used therapeutically to alleviate cramps and to improve function in daily activities by increasing range of motion.^[2][3]

In its most basic form, stretching is a natural and instinctive activity; it is performed by humans and many other animals. It can be accompanied by yawning. Stretching often occurs instinctively after waking from sleep, after long periods of inactivity, or after exiting confined spaces and areas. In addition to vertebrates (i.e. mammals and birds), spiders have also been found to exhibit stretching.^[4][5]

Increasing flexibility through stretching is one of the basic tenets of physical fitness. It is common for athletes to stretch before (for warming up) and after exercise in an attempt to reduce risk of injury and increase performance.^[6]

Stretching can be dangerous when performed incorrectly. There are many techniques for stretching in general, but depending on which muscle group is being stretched, some techniques may be ineffective or detrimental, even to the point of causing hypermobility, instability, or permanent damage to the tendons, ligaments, and muscle fiber.^[7] The physiological nature of stretching and theories about the effect of various techniques are therefore subject to heavy inquiry.

Although static stretching is part of some warm-up routines, pre-exercise static stretching usually reduces an individual's overall muscular strength and maximal performance, regardless of an individual's age, sex, or training status.^[8] For this reason, an active dynamic warm-up is recommended before exercise in place of static stretching.^[9][10][11]