Stretching is a form of physical exercise in which a specific muscle or tendon (or muscle group) is deliberately flexed or stretched in order to improve the muscle's felt elasticity and achieve comfortable muscle tone. The result is a feeling of increased muscle control, flexibility and range of motion. Stretching is also used therapeutically to alleviate cramps.
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.
Increasing flexibility through stretching is one of the basic tenets of physical fitness. It is common for athletes to stretch before and after exercise in order to reduce injury and increase performance.
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 tears, hypermobility, instability or permanent damage to the tendons, ligaments and muscle fiber. The physiological nature of stretching and theories about the effect of various techniques are therefore subject to heavy inquiry.
Studies have shed light on a large protein within skeletal muscles named titin. A study performed by Magid and Law demonstrated that the origin of passive muscle tension (which occurs during stretching) is actually within the myofibrils, not extracellularly as previously been supposed. Due to neurological safeguards against injury, it is normally impossible for adults to stretch most muscle groups to their fullest length without training due to the activation of muscle antagonists as the muscle reaches the limit of its normal range of motion.
Types of stretches
There are four different types of stretching: ballistic, dynamic, proprioceptive neuromuscular facilitation, and static stretching. Ballistic stretching is a rapid bouncing stretch in which a body part is moving with momentum that stretches the muscles to a maximum. Muscles respond to this type of stretching by contracting to protect itself from over extending. Dynamic stretching is a walking or movement stretch. By performing slow controlled movements through full range of motion, a person reduces risk of injury. Proprioceptive neuromuscular facilitation (PNF) is a type of stretch for a particular muscle and its specific job, so resistance should be applied, then the muscle should be relaxed. Static stretching is a type of stretch whereby a person stretches the muscle until a gentle tension is felt and then holds the stretch for thirty seconds or until a muscle release is felt, without any movement or bouncing.
A study of soccer players showed a group who did dynamic warm up exercises and static stretches had fewer knee injuries than one that did neither.
One review suggests that there are many beneficial stretches that can improve range of motion (ROM) in athletes, especially runners. It is also suggested that one stretching exercise may not be enough to prevent all types of injury, and that, multiple stretching exercises should be used to gain the full effects of stretching. It has also been suggested that proprioceptive neuromuscular facilitation (PNF) stretching yields the greatest change in range of motion, especially short-term benefits. Reasoning behind the biomechanical benefit of PNF stretching points to muscular reflex relaxation found in the musculotendinous unit being stretched.[clarification needed] Others[who?] suggest that PNF benefits are due to influence on the joint where the stretch is felt.[clarification needed]
If done properly, stretching can prevent injury, relax the muscles, increase range of motion and flexibility, and better one's performance, especially athletes. Although stretching does not prevent injury, it can reduce the risk greatly; especially if one stretches properly and on a regular basis. Stretching is more beneficial to those who stretch regularly, as opposed to those people who stretch occasionally. Stretching increases blood flow which prevents hardening of the arteries and it also produces synovial fluid, which lubricates the joints that are surrounded by the muscles; which in turn helps prevent arthritis. Stretching stabilizes the body's natural balance and posture, and aligns the joints leading to better coordination. After any physical activity, there is a buildup of lactic acid in one's body and by stretching the lactic acid is removed, therefore alleviating any muscle pain or cramps. It is important for a person to perform each of the four types of stretching properly to gain the benefits.[unreliable medical source?] It has been shown for example that intensive stretching has a synergistic effect with Plyometric training by protecting the joint and making it more receptive to the benefits of the plyometric drills.
Over-stretching or stretching to a point where pain is felt may be inappropriate and detrimental. Effects on performance, both short- and long-term, may include predisposition to injury and possible nerve damage. Other research concludes that active stretching routines will reduce muscle-tendon viscosity and increase muscle compliancy and elasticity. In sports activities where there are little or no short-stretching cycles, (bicycling, jogging, etc.) stretching routines may be detrimental to athletic performance and have no effect on reducing injuries.
Other theories included claim active static stretching increases inflow of Ca2+ from extra cellular spaces into the muscles being stretched. The increase of Ca2+ reduced the muscle twitch tension by up to 60%. Reasoning behind this claim is that increased levels of Ca2+ in resting muscles predisposes individuals to fatigue quicker than individuals who did not stretch.
Static stretching in general reduces strength and power. It has also been shown to reduce stability in squats. Static stretching did not help reduce lower leg injuries in a study of military recruits. Static stretching prior to ballistic or heavy activity often decreases performance and may even predispose to injury.
Some people are more flexible than others as defined by individual body flexibility score; this includes sex differences where females are generally more flexible than males. Stretching may not increase range of motion, but rather increase individual stretch tolerance, becoming detrimental to athletic performance. Among the factors these studies measure are capsular mobility, FlexiScore and joint-muscle compliance.
Results of research by Witrouw et al. found that: each of which has a different consideration based on individual activity:
- In activities where stretch-shortening cycles (SSC) are more prevalent, such as sprinting and jumping, the muscle-tendon units need to store and use more elastic energy
- In activities which do not require as much SSC such as jogging, a more elastic muscle-tendon unit is not needed.[clarification needed]
The reason behind conflicting data is claimed to be due to the different levels of observed sports activity.
- Weerapong, Pornratshanee; Hume, Patria A. and Kolt, Gregory S. (2004). "Stretching: Mechanisms and Benefits for Sports Performance and Injury Prevention". Physical Therapy Reviews 9 (4): 189–206. doi:10.1179/108331904225007078.
- Dagenais, Marc (December 2011) Softball Training Tips – Do you know how to stretch? softballperformance.com
- Prentice, William E. (2003) Principles of Athletic Training, McGraw Hill, ISBN 0071092552.
- Tsatsouline, Pavel (2001). Relax into stretch: instant flexibility through mastering muscle tension. Dragon Door Publications. ISBN 978-0-938045-28-1.
- University of California Regents > Muscle Physiology – Types of Contractions. muscle.ucsd.edu
- Yessis, Michael (2006). "Runners Need Active Stretching". AMAA Journal Winter 18 (2): 8–18.
- Sharman, MJ; Cresswell, AG; Riek, S (2006). "Proprioceptive neuromuscular facilitation stretching : Mechanisms and clinical implications". Sports medicine (Auckland, N.Z.) 36 (11): 929–39. doi:10.2165/00007256-200636110-00002. PMID 17052131.
- Appleton, Brad D. (1993) Stretching and Flexibility – Everything you never wanted to know.
- De Bremaeker, Marc (2013) Plyo-Flex. ISBN 978-1938585104
- Witvrouw, E; Mahieu, N; Danneels, L; McNair, P (2004). "Stretching and injury prevention: An obscure relationship". Sports medicine (Auckland, N.Z.) 34 (7): 443–9. doi:10.2165/00007256-200434070-00003. PMID 15233597.
- Nelson, AG; Kokkonen, J; Arnall, DA (2005). "Acute muscle stretching inhibits muscle strength endurance performance". Journal of strength and conditioning research / National Strength & Conditioning Association 19 (2): 338–43. doi:10.1519/R-15894.1. PMID 15903372.
- Simic, L., Sarabon, N. and Markovic, G. (2013), Does pre-exercise static stretching inhibit maximal muscular performance? A meta-analytical review. Scandinavian Journal of Medicine & Science in Sports, 23: 131–148. doi: 10.1111/j.1600-0838.2012.01444.x
- Acute effect of passive static stretching on lower-body strength in moderately trained men.Gergley JC.J Strength Cond Res. 2013 Apr;27(4):973-7. doi: 10.1519/JSC.0b013e318260b7ce.PMID 22692125[PubMed - in process]
|Wikimedia Commons has media related to Stretching.|
- Andersen, J. C. "Stretching Before and After Exercise: Effect on Muscle Soreness and Injury Risk". Journal of Athletic Training 40(2005): 218–220.
- Anderson, Bob. "Stretching: 30th Anniversary Edition". Shelter Publications (2010)
- Cheung, Karoline, Patria A. Hume, and Linda Maxwell. "Delayed Onset Muscle Soreness: Treatment Strategies and Performance Factors". Sports Medicine 33.2(2003): 145–164.
- LaRoche, Dain, and Declan A. J. Connolly. "Effects of Stretching on Passive Muscle Tension and Response to Eccentric Exercise". American Journal of Sports Medicine 34.6(2006): 1000–1007.
- Shrier, Ian. "When and Whom to Stretch?" Physician & Sportsmedicine 33.3(2005): 22–26.
- An article on the benefits of Static Stretching.
- An article about different types of stretching for sports.
- An article about stretching in the martial arts, and the different ways in which stretches are employed in them as compared with others sports.