All of us have done it at some time or other, some of us do it on a regular basis with an almost religious fanaticism, others only occasionally when we remember that we should be doing it, others have tried but stopped because they got bored. So what is the truth about stretching? Should we be doing it, which methods should we be using, how often and when? Will it make us perform better, protect us from injury and allow us to have a better overall sporting life?
The benefits of the act of stretching have always been assumed to be that of protecting the muscles from injury during the sporting event itself, whether in training or racing, and that of improving performance.
The exact mechanics of what happens during a stretch are rather complicated though recent research is enabling researchers to learn more. The justification for regular stretching is that it is thought to increase flexibility, both my making muscles more supple and by retraining the nervous system to tolerate stretching further. This last point is very important in that it would suggest that the muscles do not actually become any longer but the tolerance of pain towards the movement of stretching itself are increased. It has been observed that flexibility from regular stretching gradually disappears when the practice is stopped – almost completely within a period of 4 weeks.
Power generation, during athletic activity, is caused by the muscles and tendons storing energy and then releasing it like a spring. Too much flexibility may reduce the muscle’s natural spring which would be detrimental in sports that involve running or sudden changes of direction. At the same time too little flexibility may increase the risk of injury to the muscle, as the muscles are unable to sufficiently lengthen and absorb the energy or force being applied to them.
The majority of the amateur sporting population, and indeed the readers of the present article, would probably agree with these above considerations. But are they correct and if so which type of stretching is most beneficial?
We can identify 4 types of stretching that have been and are utilised.
Static Stretching: in which a muscle is stretched to the point of mild discomfort and held in that position, typically for at least 30 seconds or longer.
Dynamic Stretching: gentle repetitive movements are performed, such as leg swings or front and side lunges, where the range of motion and movement is gradually increased, , but always remains within the normal range of motion. Pain or discomfort are avoided.
Proprioceptive Neuromuscular Facilitation (PNF): a generally therapeutic method utilised in rehabilitation or treatment of traumatised patients. The method requires the intervention of a trained facilitator. There are various methods but typically PNF involves holding a stretch while contracting and relaxing the muscle. The method has also been utilised by numerous professional athletes but the requirement of a facilitator would seem to discourage it’s use by the average amateur athlete. As a recent meta analysis concluded, “Research indicates that PNF stretching, ……………….., is effective in improving and maintaining ROM, increasing muscular strength and power, and increasing athletic performance, especially after exercise. However, proper protocol and consistency must be followed to attain and maintain the benefits of PNF techniques.” Proprioceptive Neuromuscular Facilitation (PNF): Its Mechanisms and Effects on Range of Motion and Muscular Function. Kayla B. Hindle, Tyler J. Whitcomb, Wyatt O. Briggs, and Junggi Hong.
Ballistic Stretching: this method involves going into a stretch and performing bouncing or jerking movements in order to increase the range of motion. This method is generally discouraged as the excessive bouncing movement can easily lead to injury when not monitored correctly. Research which concentrated on comparing ballistic stretching to dynamic stretching has shown that there is no difference in performance benefit of the two methods - "The acute effects of dynamic and ballistic stretching on vertical jump height, force, and power." Jaggers JR, Swank AM, Frost KL, Lee CD. Journal of Strength & Conditioning (Nov.2008).
We can therefore conclude that the latter two methods of stretching (ballistic and PNF) are not generally useful or conducive to amateur athletes and, in the case of ballistic, certainly not more effective than dynamic stretching with the added risk of injury.
Quite a number of studies have been made on the use of pre and post activity stretching in order to ascertain what, if any advantages may accrue. In the majority of cases these studies concerntrated on the use of Static Stretching.
One of the most important trials was conducted on 2,631 army recruits ( a sufficient number to disallow for any problem of small statistical differences). The conclusion of this trial was that “…………..three months of routine stretching before exercise didn’t appreciably reduce injury risk.” A randomized trial of pre-exercise stretching for prevention of lower-limb injury.
Pope RP, Herbert RD, Kirwan JD, Graham BJ.
However a joint study conducted by the “Knowledge Centre for the Health Services, Norway and the University of Sydney concluded that “Stretching before and after physical activity does not appreciably reduce all-injury risk, but probably reduces the risk of some injuries, and does reduce the risk of bothersome soreness.” A pragmatic randomised trial of stretching before and after physical activity to prevent injury and soreness. Gro Jamtvedt, Robert D Herbert, Signe Flottorp, Jan Odgaard-Jensen, Kari Håvelsrud, Alex Barratt, Erin Mathieu, Amanda Burls, Andrew D Oxman. Br J Sports Med (2010)
Further evidence for the lack of advantages were cited in a meta analysis. “The evidence from randomised studies suggests that muscle stretching, whether conducted before, after, or before and after exercise, does not produce clinically important reductions in delayed-onset muscle soreness in healthy adults.” Stretching to prevent or reduce muscle soreness after exercise. Meta Analysis.
Herbert RD, de Noronha M, Kamper SJ. Cochrane Database Syst Rev. (2011).
Yet another study aimed at deriving an estimate of the acute effects of pre-exercise static stretching (SS) on strength, power, and explosive muscular performance concluded that “………the usage of SS as the sole activity during warm-up routine should generally be avoided. Does pre-exercise static stretching inhibit maximal muscular performance? A meta-analytical review. Simic L, Sarabon N, Markovic G. Scandinavian Journal of Science & Medicine in Sports (2012).
We can therefore conclude that there is probably no great advantage in the practice of static stretching within a training or racing protocol for an amateur runner. There is very little flexibility to be gained while the prevention of injury would not seem to be a significant factor.
So what about Dynamic Stretching? In reality this is not so much a stretching protocol as that of a warming up and preparation of the various muscles for the upcoming training or racing.
“There are few sports where achieving static flexibility is advantageous to success in the sport. Therefore according to the principle of specificity it would seem to be more advantageous to perform a dynamic warm-up which more resembles the activity of the sport.” Dynamic Flexibility training, Strength and conditioning Journal. HENDRICK, A. (2000)
Moving the limbs, whether lower or upper, through a series of movements that are similar to those which will be utilised during the actual activity increases the blood flow and consequent temperature and produces a temporary flexibility in these areas. “Dynamic Flexibility increases core temperature, muscle temperature, elongates the muscles, stimulates the nervous system, and helps decrease the chance of injury.” Dynamic Flexibility. Strength and conditioning Journal FREDERICK, G. (2001).
These movements are also functional in that they also solicit the movement of surrounding areas, element which is missing in static stretching protocols. Dynamic stretching can include basic movements such as leg swings or lunges, to more dynamic and complete movements such as High Knee Skip or Run, Heel Ups, Straight Leg Skips, Carioca or Backward Run. Activities which may also be described as running drills or coordination protocols.
Some authors have shown that a team which dynamically stretched before activity had fewer injuries than a team which utilised static stretching. Guidelines to the implementation of a dynamic stretching routine. MANN, D. and JONES. M. Strength and Conditioning Journal (1999).
In his book “Functional Training for Sports” (2004) ed. Human Kinetics, the coach Michael Boyle cites the courses run by him and his assistants for the entire summer of 2002, in which they conducted 26,000 workouts utilising dynamic stretching protocols and didn’t have one student pulling a major muscle that required medical attention. Anecdotal evidence rather than scientific research but rather convincing considering the source.
So where does that leave us?
If you have been practicing static stretching without any negative consequences then it’s probably safe to continue doing so. Adding some dynamic stretching may not be a bad idea.
If on the other hand you’ve been static stretching but have not seen any improvements in your performance or maybe you’ve experienced injuries it may be advisable to change this for a regime of dynamic stretching.
If you haven’t been doing any form of stretching, now may be the time to try some dynamic stretching routines in order to improve performance and avoid injury.