stretchingStretching  prior to sports participation has been a common practice for many years.  One would struggle to walk past a track or playing field without seeing participants engaging in standard pre-workout quadricep, hamstring or calf stretches.  The coaches of our youth echo in our heads with proclamations of the virtues of stretching so that you don’t “pull a quad” when you start running.
However, how did the coaches of yore know this to be true?  Is there evidence to support this mainstay practice or are we just prescribing to an ‘old wives tale’ or in this case, an ‘old coaches tale’ ?
In the athletic world, there is a  ritualistic belief that pre activity or event stretching helps improve performance.  This belief  has been somewhat disproven over the past several years as static stretching has been shown to decrease performance especially when the duration of static stretch is greater than 30 seconds, when performed as a separate component from dynamic stretching and when performed too close in time to the initiation of a performance event.  Secondarily, coaches have promoted pre-event static stretching based on the belief that a tight musculo-tendinous unit is less extensible indicating that its tolerance for  tissue elongation is diminished.  This belief has led to the assumption that stretching will reduce muscle and tendon strain and injury.
As previous beliefs about static stretching and athletic performance have been challenged, the effects of  such stretching upon injury prevention deserves renewed consideration.

hamstring stretchA 2004 systematic review of the literature  as presented in the research journal Medicine and Science in Sports and Exercise summarized research on flexibility and its relation to stretching and sports injuries in the context of other risk and protective factors. Secondarily, they assessed the evidence for the effectiveness of stretching as a tool to prevent injuries in sports.  This review identified 361 studies between 1961 and 2002  that focused on the effects of stretching on performance and injury prevention, and adverse effects of stretching and flexibility.

The authors of this review state that there is not sufficient evidence to endorse or discontinue routine stretching before or after exercise to prevent injury among competitive or recreational athletes.

calf stretchA 2014 meta analysis and systematic review of the literature, as presented in the British Journal of Sports Medicine, was performed to determine whether sole performance of exercises including: strength training, static stretching, proprioception and combinations of these exercises as part of a warmup routine can reduce sports injuries.  This review identified  and analyzed 25 trials, including 26,610 participants with 3464 injuries.

The analysis showed no beneficial effect for stretching , whereas studies with multiple exposures including:  proprioception training and strength training  showed a tendency towards increasing effect upon reducing injury.   The assessment found that both acute injuries and overuse injuries could be reduced by the physical activity procedures.

The authors conclude by stating despite a few outlying studies, consistently favorable estimates were obtained for all injury prevention measures except for stretching. Strength training reduced sports injuries to less than 1/3 and overuse injuries could be almost halved.

A 2008 systematic review of the literature   as presented in Research in Sports Medicine was undertaken to assess the efficacy of static stretching as part a warm-up for the prevention of exercise-related injuries.  Literature search for articles post 1990 and pre January 2008 as related to static stretching and injury identified (7) total studies out of 364 that met the inclusion / exclusion criterion.

hip stretchFour random controlled trials concluded that static stretching was ineffective in reducing the incidence of exercise-related injury while only one of the three controlled clinical trials concluded that static stretching did reduce the incidence of exercise-related injury. Three out of the seven studies noted significant reductions in musculotendinous and ligament injuries following a static stretching protocol despite nonsignificant reductions in the all-injury risk.

The authors felt that reduced ligament and musculotendinous unit injury may be related to improving the flexibility of such structures by facilitating connective tissue plastic elongation.

The study concluded by stating 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.

runner stretchIn 2000, a randomized controlled trial  presented in Medicine and Science in Sports and Exercise investigated the effect of muscle stretching during warm-up on the risk of exercise-related injury.  In this study, 538 male army recruits were randomly allocated to stretch or control groups. During  an ensuing 12 weeks of training, both groups performed active warm-up exercises before physical training sessions. In addition, the stretch group performed one 20 second static stretch or each of six major leg muscle groups during every warm-up. The control group did not stretch.  During this training period, 333 lower-limb injuries were recorded, including 214 soft-tissue injuries. There were 158 injuries in the stretch group and 175 in the control group.  This study shows that there was no significant effect of pre-exercise stretching on all-injuries risk, soft-tissue injury risk , or bone injury risk.

The authors conclude by stating that a typical muscle stretching protocol performed during preexercise warm-ups does not produce clinically meaningful reductions in risk of exercise-related injury in army recruits.

 

So what is the conclusion and what should the coach and athlete do?

 

A substantial volume of scientific literature suggests that stretching before exercise does not reduce the risk of injury although a limited number of studies suggest that such activities may reduce ligament and musculotendinous injury.

 

In light of the above information and from a physical therapists’ perspective, there are several scenarios when I would incorporate a pre-activity static stretch.  Stretching may be beneficial if an athlete has an obvious mobility restriction or tissue tightness either from a previous injury, from an overuse condition or from a recent workout.  In this case, static stretching may be beneficial to gain or regain normal tissue and joint mobility necessary for sport performance.  One of the limitations of static stretch related research is that is predominantly appears to be performed on healthy individuals and does not take into account the aforementioned subgroup.  Static stretching would be an important component for this group and would need to be tissue or injury specific versus a global, generic stretching program.

 

From a coaches perspective, Based on supporting research and keeping in mind the individual needs of the athlete, the coaches and athletes will need to make judicious decisions on the best preparation for performance preparation

.stretching hamstring

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