Does Stretching improve Performance?

Does Stretching improve Performance? A Systematic and Critical Review of the Literature

Ian Shrier
Journal Sports Medicine, 2004


Although many clinicians and authors currently advise that stretching prevents injury, recent reviews have suggested that stretching immediately prior to exercise does not prevent injury. However, there is some weak evidence that stretching at other times may indeed prevent injury.
Although clinicians are now generally aware of the issues related to stretching and injury, many authors also recommend stretching to improve performance.

Does Pre-Exercise Stretching Improve Performance?
Force, Torque, and Jump: positive studies:
There were no studies that suggested that stretching is beneficial for these aspects of performance.

Force, Torque, and Jump: negative studies:
There were 20 studies that found that an acute stretching session diminshed performance. The measures included MVC, power, jump height, jump force, and hump velocity. One of these studies found static stretching detrimental for jumping, whereas dynamic stretching had no effect.

Running
The study showing that stretching was detrimental used static stretching, and the study showing that stretching was beneficial showed greater benefits with dynamic stretching compared with static stretching. Of note, although not statistically significant, the study that showed that stretching was beneficial for running had also showed that static stretching decreased jump height by 2,5%, which is the same magnitude found in other studies. Dynamic stretching had resulted in only a 0,5% decrease in jump height.

Does regular Stretching  improve performance?
Positive studies
There was 7 studies suggesting that regular stretching improves performance. The measures of performance inclueded MVC, contraction velocity, both eccentric and concentric contraction force, counter-movement jump height, and 50-yard dash.

Negative studies
There were no studies that suggested that regular stretching diminshes performance.

Equivocal studies
There were 2 studies suggesting neither an improvement nor a diminished performance.



A review of the clinical evidence strongly suggests that pre-exercise stretching decresases force production and velocity of contraction for at least part of the range of motion (ROM), and that running economy is improved. The effect on running speed remains to be determined, with 1 study suggesting that stretching is beneficial, 1 suggesting that stretching is detrimental, and 2 equivocal small studies. The effects of regular stretching are exactly opposite: regular stretching improves force production and velocity of contraction but has no effect on economy of motion. These results are consistent with the basic science evidence and mirror the results observed with respect to stretching and injury.

Acute Stretching
Running economy is improved with an acute bout of stretching.


This review found that running economy is improved, but force and velocity of contraction are decreased.
The overall effect on running speed is therefore likely to be dependent on the balance of these factors withing any particular individual. 1 article that found that stretching improved running speed found that dynamic stretching was superior to static stretching. Because dynamic stretching also requires the muscles to contract, other possible mechanisms include central programming of muscle contraction/coordination and decreased fatigue through increased warm-up activity.

Regular Long-Term Stretching
Although the immediate effects of stretching decrease visco-elasticity and increase stretch tolerance, the effect of stretching over 3 to 4 weeks appears to affect only stretch tolerance, with no change in visco-elasticity.
The mechanism by which regular long-term stretching improves performance is likely related to stretch-induced hypertrophy occurs event though the muscle has not been contracting.

Limitations
There are many different ways to stretch, Static stretching was used in most of the studies, but the effects were observed with PNF stretching as well. Dynamic stretching is a combination of both stretching as well. Dynamic stretching is a combination of both stretching and warm-up

A muscle that contracts immediately after a stretch (e.g., jumping up immediately agter landing from a short jump) produces more force than a muscle that was not stretched. This is an important phenomenon but unrelated to the clinical effects of pre-exercise stretching.
In summary, the evidence suggests that stretching immediately prior to exercise decreases the results on performance tests that require isolated force or power. The effect on running speed remains to be determined. On the other hand, regular stretching will improve the results for all activities. This is similar to the fact that stretching immediately prior to exercise does not reduce the risk of injury, but that regular stretching may reduce the risk of injury.


Future research should investigate the cellular and molecular mechanisms by which the effects of stretching occur, whether the added benefit of regular stretching is as effective as other types of performance enhancement exercises being promoted (e.g., plyometrics, increased weight training), and whether the same effects are seen in the presence of injury.