Review of research on Stretching by Osteopath Anthony Dileo
Not many days go by where osteopaths aren't asked about stretching. The how to, what's effective when to, how long for, when not to, how many repetitions questions are important questions.
The answers are also significantly important. Health is individualistic and collective. We use the collective research and clinical experience to align the advice to the individual.
Here is a summary of some of what guides our decision making process when asked about stretching:
A Summary of the Evidence from the Article:
There little evidence that stretching decreases the risk of injury overall
There is some evidence that static stretching may reduce musculotendinous injuries.
There is good evidence that a warm up can reduce your risk of injury.
Short term gains can be achieved with static stretches held for 15-30 seconds (repeat 4-5 times).
Long-term gains can be achieved up to 6-7 weeks by holding stretches for 30 seconds (repeat 4-5 times)
Resistance Stretching can be more affective than static stretching
Stretching can reduce pain but not DOMS (Delayed Onset Muscle Soreness).
Stretching can help you recover from some injuries and for rehabilitation.
Static stretching may have a negative impact on power and performance in explosive exercises and explosive sports.
Dynamic stretching may improve performance in explosive exercise and explosive sports.
Long term stretching can improve performance and strength over time.
Older adults can benefit from different types of stretching.
Everyone responds slightly differently to stretching.
There is a consensus that there is insufficient conclusive evidence on stretching and more research is required.
Yes. The evidence here is clear but perhaps not for the reason you think.
Static stretching is proven to increase joint range of movement (1-2) and muscle length over time (3). Interestingly, the improved movement may not be caused by increased muscle length/decreased tension but rather via an increased tolerance to stretching (32). There is also evidence ‘of moderate quality’ that indicates that continual stretching will improve the flexibility of your joints (95).
Not surprisingly several authors have noted that the type of response to a stretch depends on the individual (83-85).
How long do I need to stretch to get some effect?
Clearly this is a how long is a piece of muscle question. One study has shown ‘that muscles throughout the body can be different’ (4) which is clearly a highlight in the research.
Here’s the evidence:
Stretches should be held between 10 to 30 seconds (5,39-42) and not be repeated more than 4 to 5 times (7-8).
For short term gains (e.g. for a light jog) there is no benefit in holding a stretch for longer than 15 seconds (6).
Stretching a muscle 30 seconds a day can increase range of movement for up to 6 weeks before it will reach a plateau (It will take 10 weeks if the stretch is held for 15 seconds (9)).
As an example for hamstrings it will take 6 to 8 weeks of static stretching to increase hamstring length (36-38).
Should I warm up if I want to reduce my risk of injury?
Yes. Compared with stretching there is some very strong evidence for warming up before exercise and before stretching.
A 2006 review of the literature reported sufficient evidence on the effects of warming up on reducing injury risk in humans (31). Some studies have shown that stretching for greater range of motion is more effective after a jogging or heat assisted warm-up (10-12).
What’s the most effective way to stretch?
There is still more research to be done here but there has been some good evidence for PNF (Proprioceptive Neuromuscular Facilitation). PNF Stretching is a type of stretch where the muscle you are stretching is contracted/activated during a stretch.
Various studies have concluded that both static and dynamic stretching appear equally effective at improving joint range of motion acutely or over time with training (65-68). There is some good research on PNF Stretching particularly with hamstring muscles and ankle muscles (13,14). PNF stretching is equally effective whether contractions are held for 3, 6 or 10 seconds (15).
Will Stretching decrease my pain?
Yes it can but it does depend on the type of pain. Overall there are some good studies that support stretching in pain management programs (93-94).
Some studies have shown that 12 months of stretching is as effective as strengthening exercises or manual therapy in patients with chronic neck pain (91-92). However, one study suggested that stretching had no impact on DOMS (delayed muscle onset soreness) which is muscle pain experienced after exercise (28).
Does stretching reduce my risk of injury?
It is unclear as to whether stretching will reduce your risk of injury but it is abundantly clear that more research is required here. To be fair this is a very difficult thing to measure (and to read!).
One study demonstrated a significantly lower rate of muscle-related injuries but no difference in the rate of bone or joint injuries (18). Another literature review (16) concluded that ‘There is not sufficient evidence to endorse or discontinue routine stretching before or after exercise to prevent injury among competitive or recreational athletes’ whilst another (17) examined the hypothesis that ‘stretching before exercise does not seem to confer a practically useful reduction in the risk of injury’ but also found little evidence to support that! This is clearly another highlight of this article.
One study found that ‘hamstring stretching was the most important training factor associated with reducing hamstring strain rate (19) but another hamstring study concluded that hamstring flexibility had no relationship with hamstring strains (20).
In an attempt clear things up a literature review performed in 2008 concluded that there is moderate to strong evidence that routine application of static stretching does not reduce overall injury rates. There is preliminary evidence, however, that static stretching may reduce musculotendinous injuries (29).
To follow up the 2008 review another study concluded that there is evidence that pre-participation stretching reduces the incidence of muscle strains but there was clearly a need for further research (30).
Should I stretch as part of my rehab?
Overall there is some good support for stretching as part of rehabilitation from injuries.
One study on the role of stretching during rehabilitation from grade 2 hamstring strains concluded a statistically significant shorter time of regaining normal range of motion and rehab period’(21). Another study found that patients with knee osteoarthritis can benefit from static stretching to increase knee range of motion (89). Another study found that patients with total knee replacements benefited from 2 weeks of either static, dynamic or PNF stretching to increase joint range of motion (90).
Should I stretch to improve my explosiveness in certain sports?
Certain types of stretching can actually reduce your performance in some instances and should not be performed before certain activities.
For more explosive activities (e.g. sprinting, high jump or basketball) there is some good research that supports that static stretching has a negative effect on the subsequent performance of activities involving the stretch reflex (22,23). Another study found that there was a significant reduction in muscle strength endurance after static muscle stretching (27) and that static stretching as part of a warm-up immediately prior to exercise has been shown detrimental to muscle strength (54-64) and performance in running and jumping (43-53).
Dynamic Stretching (e.g. end range arm windmills and leg swings) however has been shown to improve performance (24). Researches have also found that stretching different muscles of the body produces different results with regards to power and performance (25,26).
Some researchers report static stretching after warm-up decreases performance (76-78)while others report no change or an increase in performance (79-82) so whilst there is some good evidence against stretching, the theme of the article that “more research is required” applies here.
Will Stretching improve my overall performance and strength in the long term?
There is some good evidence that general stretching over longer term improves performance (96-97). Clearly what defines performance is in the research and is generalised here.
Has there been research on stretching for older adults?
Yes there is some evidence out there for good responses to stretching for older adults.
One study found that 60-second holds of static stretches were associated with greater improvements in hamstring flexibility compared to shorter duration holds (86). Ten weeks of static stretching of the trunk muscles was able to increase spinal mobility (combined flexion and extension) (87). Static stretching of the hip flexors and extensors may also improve gait in older adults. Furthermore, the effectiveness of type of stretching seems to be related to age and sex: men and older adults under 65 years respond better to contract-relax stretching, while women and older adults over 65 benefit more from static stretching (88).
Stretching….. An Osteopathic perspective:
A muscle as a single unit does not exist in the living human body. A functional human body cannot simply move via muscle activation alone without the assistance of literally billions of other stimuli.
Human movement requires the co-ordination of muscles, fascia, tendons, ligaments, joint capsules, nerves, blood vessels, lymphatic vessels. Add to this the health and functioning of our system on a micro and cellular level, the wiring and neurological connections between the brain and the body, the psychological effect on our system and clearly the act of stretching and its influences can be quite complex and far ranging.
This does not mean we ignore the quality of evidence and research that has been performed - it does provide a helpful guide. The osteopathic perspective allows for consideration of the current research in association with the health and functioning of the system as a whole and should be considered on an individual basis when stretching a muscle.
Article first published in www.melbourneosteopathygroup.com.au
Dadebo B, White J, George KP: A survey of flexibility training protocols and hamstring strains in professional football clubs in England. Br J Sports Med. 2004 Aug;38(4):388-94
Davis DS, Ashby PE, McCale KL, McQuain JA, Wine JM: The effectiveness of 3 stretching techniques on hamstring flexibility using consistent stretching parameters. J Strength Cond Res. 2005 Feb;19(1):27-32
Shrier I, Gossal K: Myths and Truths of Stretching: individualized recommendations for healthy muscles. The Physician and Sports Medicine 2000 Aug. 28(8)
Magnusson SP: Passive properties of human skeletal muscle during stretch maneuvers. A review. Scand J Med Sci Sports. 1998 Apr;8(2):65-77
Shrier I: Does stretching improve performance?: a systematic and critical review of the literature. Clin J Sport Med. 2004 Sep;14(5):267-73
Magnusson SP, Simonsen EB, Aagaard P, et al: Biomechanial responses to repeated stretches in human hamstring muscle in vivo. Am J Sports Med 1996;24(5):622-628
Bennell K, Tully E, Harvey N: Does the toe-touch test predict hamstring injury in Australian Rules footballers? Aust J Physiother. 1999;45(2):103-109
Evetovich TK, Nauman NJ, Conley