stretching- does it help?

Stretching before sport, competition or exercise has been the golden rule for many years and as physios we have reminded people to stretch and incorporate it into their warm-up. It is believed to prevent injury and improve performance, but for several years now we have been questioning whether this is really true. It has become a controversial topic and with it come lots of questions. Is there any benefit at all to stretching, what type of stretching is best – dynamic or static, when is it best performed and how often should it be performed? This blog will aim to summarise some of the research findings, and give some clarity on the topic.

stretching


Does stretching help improve performance?

In a review of the literature back in 2004, Ian Shrier concluded that pre-exercise stretching (stretching within 60 minutes of exercise) did not improve performance. He found that no studies suggested that stretching was beneficial for measurements of force, torque or jumps. In fact all but 1 study (ie 22 out of 23 articles) found that pre-exercise stretching actually diminished performance. The measures included MVC (Maximal Voluntary Contraction), power, jump height, jump force and jump velocity. The remaining study showed no difference. However, results are conflicting for running speed. More recently, Simic L et al (2013) and Gergley JC (2013) also found that pre-exercise stretching reduces tests of performance of strength and power.

If pre-exercise stretching doesn’t improve performance, what about regular stretching (repeated stretching over days to weeks)? Overall, the evidence was the opposite from pre-exercise stretching with the results being strong for increases in force, jump height and velocity. Therefore, stretching regularly, actually increases tests of performance.

‘Performance’ in these research studies are examined with performance tests, not with performance in the field. It is fair to extrapolate the results to exercise and performance out of the lab but keeping in mind that performance in exercise and sport is reliant on several factors, not just strength and power. Stretching may improve performance if flexibility is required in a sport such as karate where the ability to kick higher due to better flexibility will improve overall performance.

Does stretching help prevent injury?

A review of studies by Ian Shrier (2006) concluded that the clinical evidence doesn’t support that pre-exercise stretching prevents injury. Shrier wasn’t able to reach a conclusion from the studies as to whether stretching at other times prevents injury but he concluded that it may be beneficial. His key messages were:

  • Stretching immediately before exercise is different from stretching at other times.
  • Stretching immediately before exercise does not appear to prevent injury.
  • Regular stretching that is not done immediately before exercise may prevent injury.

What is the difference between static and dynamic stretching?

Dynamic stretching refers to movements through normal range of motion where the end position is not held. It helps to increase blood flow and muscle temperature and if movements used in the sport are performed, it prepares the body for that activity. Dynamic stretching is really more of a muscle activity and not stretching. A review by Gergley JC (2013) concluded that static stretching should be avoided before training the lower body or performing the 1RM (repetition maximum) in the squat exercise in favour of an active dynamic warm-up using resistance training equipment.

Static stretching involves elongating the muscle as far as tolerated and then holding it at the end position for 15-60 seconds depending on age, injury and activity level. Static stretching helps improve muscle flexibility and joint range of motion. It is a slow controlled form of stretching so is safe for most people and can be quite relaxing. Stretches can be performed 1-3 times a day.

A review into static stretching by Small et al. (2008) found that stretching failed to significantly reduce overall injury risk. This may indicate that routine application of static stretching does not reduce overall injury rates. Another study by Pope et al. (2000) studied the effects of stretching in 1538 male army recruits going through basic training. Half of these recruits stretched their calves, hamstrings, quadriceps and hips during the daily warm up. The other half completed general warm up activities with no stretching. At the end of the 11 week trial, the injuries were fairly evenly distributed between the two groups, leading the researchers to conclude that stretching did not have a significant impact on injury risk.

Stretching has also been believed to prevent Delayed Onset of Muscle Soreness (DOMS). However, a review of the literature by Herbert & Gabriel (2002) demonstrated stretching before or after exercise may also have no effect on DOMS.

Conclusion

It appears from the research that stretching does not significantly reduce DOMS, or the risk of sustaining an injury during exercise or sport. There is also clinical evidence that it can actually reduce your performance in your given sport, by reducing the force production in the lengthened muscle. There currently appears to be no good reason to stretch during your warm up for sport. Athletes should instead warm up with light cardiovascular exercises (such as jogging or cycling), and complete exercises that will activate particular muscles that will be required for that particular activity or sport. You should then complete a series of sports specific drills and skills to improve skills performance and reaction time.

It is important to also mention that just because stretching is not appropriate as a warm up, does not mean that we should no longer stretch at all. Most sports require that the athlete has some degree of sport specific flexibility to perform optimally and avoid injury. Some examples include:

  • Swimming: Freestyle requires good shoulder and thoracic flexibility

  • Football: To achieve a long and powerful kick, you must have good hip and hamstring flexibility

It is vital that athletes competing in sports (even just socially!) are aware of the flexibility requirements of their chosen sport. You must then stretch on days that you are not competing to maintain optimal flexibility for your chosen sport or exercise.

Flexibility and range of movement can also be improved with foam rolling. These effects are equal to or better than static stretching but without the impairment of performance experienced from static stretching.

Key Points:

  1. Stretching before exercise/sports decreases the results on performance that require force or power

  2. Regular stretching at other times improves performance, therefore stretches should be performed after exercise or at a time not related to exercise

  3. Stretching immediately before exercise doesn’t reduce the risk of injury

  4. Regular stretching at other times may reduce the risk of injury

  5. Static stretching as part of the warm-up pre-exercise will not reduce overall injury rates. However, there is some evidence it may prevent musculotendinous injuries (Injuries near the muscle tendon junction which can be present in running sports)

References:

Gergley JC. Acute effect of passive static stretching on lower-body strength in moderately trained men. J Strength Cond Res 2013;27(4):973-7

Herbert & Gabriel (2002). Effects of stretching before and after exercising on muscle soreness and risk of injury: Systematic review. BMJ; 325: 468.

Nelson, Sideaway, Cornwell & Heise (2001). Acute effects of passive muscle stretching on vertical jump performance. Journal of Human Movement Studies; 40(4):307-324

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Pope, Herbert, Kirwan and Graham (2000) A randomised trial of pre-exercise stretching for prevention of lower-limb injury. Medicine & Science in Health & Exercise; 32(2): 271-277.

Shrier I. Does stretching improve performance: A systematic and critical review of the literature. Clin J Sport Med 2004;14:267-273.

Shrier I. Does stretching help prevent injuries? In: MacAuley D, Best T, editors. Evidence-based sports medicine. London: BMJ Publishing Group, 2007.

Simic L, Sarabon N, Markovic G. Does pre-exercise static stretching inhibit maximal muscular performance? A meta-analytical review. Scand J Med Sci Sports 2013;23(2):131-48.

Small, McNaughton & Matthews (2008). A systematic review into the efficacy of static stretching as part of a warm-up for the prevention of exercise-related injury.

Res Sports Med;16(3):213-31.