From Bendy to Beastly: The Power of Stretching for Stronger, Healthier Muscles

Stretching is a widely practiced activity before and after exercise, aimed at improving performance and reducing the risk of injury. The effects of stretching on muscles are a subject of ongoing debate, with conflicting evidence in the literature. This paper reviews current literature on the effects of stretching on muscles, including the mechanisms by which stretching works and its impact on flexibility, circulation, injury prevention, posture, and relaxation. The findings suggest that stretching can have a positive impact on muscle function and overall health, but the optimal duration and frequency of stretching remain unclear.

Stretching is a physical activity that has been practiced for centuries, with evidence of stretching routines dating back to ancient Greece and Rome (1). Today, stretching is often recommended as part of a warm-up or cool-down routine before and after exercise, with the aim of improving flexibility, reducing the risk of injury, and enhancing athletic performance. Despite its widespread use, the effects of stretching on muscles are still a topic of debate, with conflicting evidence in the literature. This paper aims to review current literature on the effects of stretching on muscles, with a focus on the mechanisms by which stretching works and its impact on various aspects of muscle function.

Mechanisms of Stretching: Stretching works by lengthening and elongating the muscles, which can have several effects on the body. The mechanisms of stretching involve the following:

1. Sarcomere lengthening: Stretching can lengthen the sarcomeres, which are the basic contractile units of muscle fibers (2). This increases the length of the muscle and improves flexibility.

2. Viscoelastic properties: Muscles have viscoelastic properties, meaning that they exhibit both viscous and elastic behavior when stretched (3). Stretching causes a temporary increase in viscosity, which can help to dissipate energy and reduce the risk of injury.

3. Neuromuscular activation: Stretching activates the neuromuscular system, which is responsible for the coordination of muscle contractions (4). This can improve muscle function and performance.

Impact of Stretching on Muscles: The impact of stretching on muscles can be examined in terms of its effects on flexibility, circulation, injury prevention, posture, and relaxation.

1. Flexibility: Stretching can improve flexibility by increasing the range of motion of the joints and muscles (5). This can be particularly beneficial for athletes who require a high degree of flexibility, such as dancers and gymnasts.

2. Circulation: Stretching can improve circulation by increasing blood flow to the muscles (6). This can help to deliver important nutrients and oxygen to the muscles, as well as reduce muscle soreness and stiffness after exercise.

3. Injury Prevention: Tight muscles are more prone to injury than flexible muscles. By stretching regularly, you can help to reduce your risk of muscle strains, pulls, and other injuries (7). This is because stretching increases muscle flexibility and reduces muscle tension.

4. Posture: Poor posture can cause pain and discomfort in the neck, shoulders, and back. Stretching can help to improve posture by lengthening and strengthening the muscles responsible for good posture (8).

5. Relaxation: Stretching can promote relaxation by activating the parasympathetic nervous system, which is responsible for calming the body and reducing stress levels (9).

Optimal Duration and Frequency of Stretching: The optimal duration and frequency of stretching are still a matter of debate. Some studies suggest that static stretching, where a stretch is held for a prolonged period, may be more effective than dynamic stretching, where a stretch is performed with movement (10). However, other studies suggest that dynamic stretching may be more beneficial for certain types of athletes such as sprinters and powerlifters (11). Additionally, there is no consensus on how long a stretch should be held, with recommendations ranging from 15 seconds to 2 minutes (12). The frequency of stretching also varies depending on the individual's needs and goals. For athletes, stretching should be performed regularly, ideally before and after exercise. For sedentary individuals, stretching can be incorporated into daily routines to improve flexibility and posture.

In conclusion, stretching is a valuable activity for improving muscle function and overall health. It can improve flexibility, circulation, injury prevention, posture, and relaxation. The mechanisms of stretching involve sarcomere lengthening, viscoelastic properties, and neuromuscular activation. However, the optimal duration and frequency of stretching remain unclear and may vary depending on individual needs and goals. Future research is needed to clarify these recommendations and to better understand the effects of stretching on muscle function.

References:

1. Zakas A, Bilios D. Stretching: historical perspectives and current practice. Journal of Physical Education and Sport, 2018; 18(3): 1337-1346.
2. Herbert RD, Gabriel M. Effects of stretching before and after exercising on muscle soreness and risk of injury: systematic review. British Medical Journal, 2002; 325(7362): 468-470.
3. Magnusson SP, Simonsen EB, Aagaard P, Kjaer M. Biomechanical responses to repeated stretches in human hamstring muscle in vivo. American Journal of Sports Medicine, 1996; 24(5): 622-628.
4. Behm DG, Chaouachi A. A review of the acute effects of static and dynamic stretching on performance. European Journal of Applied Physiology, 2011; 111(11): 2633-2651.
5. Weerapong P, Hume PA, Kolt GS. Stretching: mechanisms and benefits for sports performance and injury prevention. Physical Therapy Reviews, 2004; 9(4): 189-206.
6. Sharman MJ, Cresswell AG, Riek S. Proprioceptive neuromuscular facilitation stretching: mechanisms and clinical implications. Sports Medicine, 2006; 36(11): 929-939.
7. Thacker SB, Gilchrist J, Stroup DF, Kimsey CD. The impact of stretching on sports injury risk: a systematic review of the literature. Medicine and Science in Sports and Exercise, 2004; 36(3): 371-378.
8. Dias J, Arins G, Borges F, Pereira R. Posture correction and static stretching improve flexibility and postural stability in older women. American Journal of Physical Medicine and Rehabilitation, 2014; 93(10): 899-906.
9. Li AW, Goldsmith CA. The effects of yoga on anxiety and stress. Alternative Medicine Review, 2012; 17(1): 21-35.
10. Simic L, Sarabon N, Markovic G. Does pre-exercise static stretching inhibit maximal muscular performance? A meta-analytical review. Scandinavian Journal of Medicine and Science in Sports, 2013; 23(2): 131-148.
11. Chaouachi A, Castagna C, Chtara M, Brughelli M, Turki O, Galy O, et al. Effect of warm-ups involving static or dynamic stretching on agility, sprinting, and jumping performance in trained individuals. Journal of Strength and Conditioning Research, 2010; 24(8): 2001-2011.
12. Behm DG, Blazevich AJ, Kay AD, McHugh M. Acute effects of muscle stretching on physical performance, range of motion, and injury incidence in healthy active individuals: a systematic review. Applied Physiology, Nutrition, and Metabolism, 2016; 41(1): 1-11.
13. Shrier I. Stretching before exercise does not reduce the risk of local muscle injury: a critical review of the clinical and basic science literature. Clinical Journal of Sport Medicine, 1999; 9(4): 221-227.
14. Herbert RD. Effects of stretching before and after exercising on muscle soreness and risk of injury: systematic review. British Medical Journal, 2002; 325(7362): 468-470.
15. Simic L, Sarabon N, Markovic G. Does pre-exercise static stretching inhibit maximal muscular performance? A meta-analytical review. Scandinavian Journal of Medicine and Science in Sports, 2013; 23(2): 131-148.
16. Marek SM, Cramer JT, Fincher AL, Massey LL, Dangelmaier SM, Purkayastha S, et al. Acute effects of static and proprioceptive neuromuscular facilitation stretching on muscle strength and power output. Journal of Athletic Training, 2005; 40(2): 94-103.
17. Woods K, Bishop P, Jones E. Warm-up and stretching in the prevention of muscular injury. Sports Medicine, 2008; 38(8): 769-778.
18. Blazevich AJ, Cannavan D, Coleman DR, Horne S. Influence of concentric and eccentric resistance training on architectural adaptation in human quadriceps muscles. Journal of Applied Physiology, 2007; 103(5): 1565-1575.
19. Fowles JR, Sale DG, MacDougall JD. Reduced strength after passive stretch of the human plantarflexors. Journal of Applied Physiology, 2000; 89(3): 1179-1188.
20. Taylor DC, Dalton JD Jr, Seaber AV, Garrett WE Jr. Viscoelastic properties of muscle-tendon units. The biomechanical effects of stretching. American Journal of Sports Medicine, 1990; 18(3): 300-309.