Stretching

Stretching is a form of physical exercise used to expand and flex specific muscles or tendons. A tendon is the tissue that connects a muscle to a bone. By performing these movements, individuals aim to improve muscle elasticity and achieve comfortable muscle tone. This process results in better muscle control, increased flexibility, and a wider range of motion. The range of motion, often called ROM, is the specific angle at which a joint can move.

Stretching is a natural and instinctive activity. It is performed by humans and many other animals, including vertebrates like birds and mammals. Even spiders have been observed exhibiting stretching behaviors. Often, creatures stretch instinctively after waking from sleep or after long periods of inactivity.

Scientists study the physiological mechanisms that make stretching work. One important discovery involves a large protein called titin, which is found within the myofibrils of skeletal muscles. Myofibrils are the tiny fibers that make up a muscle. A study by Magid and Law showed that passive muscle tension actually originates within these myofibrils. This challenged previous ideas that tension came from outside the muscle fibers. There are currently two main theories explaining how stretching increases flexibility. The sensory theory suggests that stretching helps the muscle-tendon units, or MTUs, adapt to reduce pain signals sent to the brain. The mechanical theory suggests that stretching decreases MTU stiffness or increases the number of sarcomeres in series. Sarcomeres are the basic units of muscle contraction.

Stretching techniques are categorized by how they are performed. Stretches can be static or dynamic. Static stretches are performed while staying in one stationary position. Dynamic stretches involve the actual movement of the muscle. They can also be classified as active or passive. Active stretches use internal forces generated by your own body. Passive stretches rely on external forces, such as an object or another person.

Dynamic stretching is often used to increase blood flow and loosen muscle fibers. A common example of a dynamic stretch is the lunge. Another type is ballistic stretching, which uses momentum. This involves bouncing or swinging at high speeds to move a muscle beyond its typical range. While ballistic stretching can be used with tools like resistance bands, it may also cause damage to the joints.

Static stretching includes several different methods. The simplest version is the static-passive stretch. This method brings a joint to its end range of motion and holds it using external forces. A more advanced technique is called proprioceptive neuromuscular facilitation, or PNF stretching. PNF involves both active muscle contractions and passive external forces. This method uses neuromuscular reeducation to potentially yield better results for strength. PNF stretching may involve contracting the agonist muscles, the antagonist muscles, or both. Antagonist muscles are the muscles that oppose a specific movement.

The effectiveness of PNF may depend on how long the person stretches before performing a task.

Athletes use stretching to manage performance and injury risks. Many athletes use dynamic stretching as part of a warm-up routine. Research shows that dynamic warm-ups can lead to short-term gains in muscle strength. These gains include faster sprint times, higher vertical jumps, and faster baseball bat swings. However, the timing of static stretching is very important. If a person performs static stretching for a long duration before exercise, it may reduce performance. Specifically, holding a static stretch for more than 60 seconds can temporarily reduce overall muscular strength. This effect occurs regardless of a person's age, sex, or training status.

Stretching also has different effects on injury prevention and muscle soreness. Dynamic stretching during a warm-up has been shown to decrease injury risk for basketball, soccer, and volleyball players. However, evidence regarding whether stretching prevents general injury is still considered controversial. Static stretching can decrease the risk of muscle injury, but it might also increase the risk of bone and joint injuries. Many people stretch to help with delayed onset muscle soreness, also known as DOMS. This soreness typically appears about 48 hours after an exercise bout. While stretching might provide psychological value during this time, there is no evidence that it actually decreases the soreness itself.

Beyond physical benefits, stretching can positively influence the mind. Research indicates that stretching may reduce feelings of anxiety, depression, hostility, fatigue, and confusion. These benefits are particularly notable in individuals with sedentary lifestyles, meaning people who sit for long periods. Improvements in mood have been seen to correlate with better cognitive function, which is how the brain processes information. Regular stretching is associated with increased vigor. This vigor may help activate brain regions linked to improved cognitive abilities. By addressing physical tension, stretching can promote overall mental well-being.