To Stretch or not to Stretch

As a sports medicine physician who specializes in the treatment of predominately running and swimming related injuries I am constantly asked the question, “Doc, should I be stretching this”, or a patient will state “I have been stretching and stretching and it’s not getting better”.  It is understandable why many athletes are confused as to whether or not they should stretch in order to recover from an injury but what really confuses them is should an athlete stretch to PREVENT AN INJURY.  I will address both topics and provide current research to help explain when an athlete should or should not stretch when attempting to prevent or recover from an injury.

Let us start by looking at the official United States government position on stretching. The Center for Disease and Control (CDC) performed a meta-analysis of studies on the impact of STRETCHING TO PREVENT INJURY. The conclusion was that stretching “APPEARED NOT BE HELPFUL IN THE PREVENTION OF INJURIES”.  For those of you who are outraged at this statement let me clarify it a little more.  They said it “was not helpful in the PREVENTION of injuries.  They did not say that if you are injured you should not stretch. Steven Thacker, MD is the director of epidemiology at the CDC.  He said “We want people to do things that have been DOCUMENTED to prevent injury, which includes things like improving balance, strength and conditioning.  We do not want people stretching thinking they will be all right”.  Joel Cramer PhD is a professor of Kinesiology (study of movement) at the University of Texas. He has investigated static stretching on the quadriceps muscles.  “We found that static stretching seems to decrease the muscles ability to PRODUCE FORCE AT BOTH SLOW AND FAST VELOCITIES”. So it appears that static stretching may be detrimental to performance!  A study done by the American Journal of Sports Medicine compared two groups of runners.  For 16 weeks 167 runners were told NOT TO STRETCH.  159 runners were told TO STRETCH for 16 weeks.  At the end of the study only 23 of the NON-STRETCHING runners had suffered a running related injury compared to 26 OF THE RUNNERS THAT STRETCHED!  A review study appearing in the British Medical Journal sought to determine if stretching BEFORE or AFTER exercise helped muscle soreness, athletic performance or injury risk.  Their conclusions were startling.  “Stretching produced non-significant reductions in muscle soreness and that it DID NOT PRODUCE USEFUL REDUCTIONS IN INJURY RISK”.  In October 2004 Runner’s World offered this opinion, “The basic science and clinical evidence suggests! In fact even the United States Army and Marine Corp’s have found that stretching does not protect their military recruits from injury.

So if stretching does not prevent injury during exercise what does?  The research is clear on this topic.  Warming up prior to running (or any exercise) increases circulation making muscles more elastic and able to absorb shock.  Warming up also increases the temperature in your joints making the fluid inside less viscous and less likely to injure.  Bodybuilders have known this for years.  Would a bodybuilder walk into a gym, load up the bench press and start lifting repetitive, heavy presses?  No!  They perform lighter more rapid sets which increase the circulation to the muscle and warms up the associated joints.  Static stretching decreases circulation rather than enhancing it.  Do an experiment on yourself.  Hold your index finger back towards your body.  What color is it turning?  It should be turning white indicating a DECREASE in blood flow.  Now perform multiple grips with your fingers.  Notice the color of your fingers and palm.  The American journal of Sports medicine confirmed this by finding that warming-up was an effective strategy for preventing running injuries compared to static stretching.  The other main way to prevent running injuries is conditioning.  We have probably all heard of the “10% rule”.  Why do we only want to increase our mileage by 10% at a time?  TO PREVENT INJURY! So how does this work.  Again let us look at the analogy of a bodybuilder.  A weightlifter does not begin their first day by bench-pressing 300 lbs.  They begin with 100 lbs. and gradually increase the weight little by little.  This is called conditioning.  An NFL player goes through training camp, pre-season and then finally starts the regular season in order to condition their body for the rigors of the regular and punishing NFL season.  With running this principle is the same.  When we run our feet strike the ground between 1000-2000 times per mile.  When we foot strike we use our gastrocnemius (calf) muscle to push off which is the equivalent of doing 1000-2000 calf raises for every mile you run!  Surely one can understand how putting this amount of strain on a muscle requires conditioning and why the 10% rule is important.

Although stretching does not prevent injury it can improve flexibility.  The next question should be then, “Does increase flexibility decrease injury or increase performance”?  The proper answer is, “It depends what activity you are doing”.  While increase flexibility is important in gymnastics it is not in running.  It is interesting that in the running community I hear from runners all the time that they over-pronate (which is equivalent to saying you are hyper-flexible in the ankle and foot).  Overpronation requires stability shoes or motion control shoes or even custom molded orthotics (braces).  By wearing stability or motion control shoes you “STABILIZE” your knees, ankles and feet which results in a decreased range of motion or a decrease in pronation.  I also hear this from patients with back problems.  They will explain how they are stretching their back and in the same breath explain how they are doing “STABILITY’ work and doing “CORE STABILITY”. So on one hand runners are always trying to prevent motion with stability and motion control shoes, braces, straps, “CORE” training etc yet on the other hand they have been led to believe that they are not flexible enough and this lack of flexibility is causing them injury.  Another point concerning flexibility is “How much is too much”?  Take for example the ability to scratch your own back.  With your right arm reach behind your own back and see how high up your back you can scratch.  Does it seem likely that if you could scratch the back of your own head that you would be at a decreased risk of injury?  Of course not.  In fact that would be considered hyper-flexible and unstable thus predisposing you to injury in the shoulder area.

Let us not “Throw the baby out with the bath water”.  Although it is clear after reviewing all of the scientific data I can find that stretching does not protect a runner from injury nor increase performance it has been shown to help ONCE A RUNNER IS INJURED”.  This is the point that confuses a lot of medical professionals and runners so let me repeat it.  STRETCHING DOES NOT PROTECT US OR PREVENT INJURY…….BUT…….ONCE INJURED STRETCHING CAN HELP RECOVER FROM INJURY AND POSSIBLY PREVENT THAT VERY SAME INJURY FROM OCCURING AGAIN.  In my efforts to treat such conditions as plantar fasciitis, achilles tendonitis, calf and hamstring pulls/strains and piriformis syndrome to name a few stretching is an integral part of the rehabilitative process.  In fact research has shown that stretching for 30-40 seconds repetitively throughout the day is superior to performing one bout of stretching daily.
Let’s review the main points.

  1. Stretching will not protect you from injury
  2. Warming up the associated muscles and joints will offer some protection.
  3. Once injured stretching may be a useful and beneficial part of the rehabilitative process.
I know this article will enrage some, cause others jaws to drop in disbelief and still in some confirm what they already knew.  But I must make this point.  The views expressed in this article are not my opinion they are the opinion of the American Journal of Sports medicine, Runners World, British Journal of Sports Medicine, Biomechanics Journal, Journal of Strength and Conditioning Research and Exercise and Science in Sports Medicine.  These are leading; premier journals in the world of sports medicine, running biomechanics and running related injuries.  My views as a sports injury specialist have changed over times as my knowledge and understanding have grown.  Being in constant pursuit of knowledge has helped me stay abreast of the newest and best treatment approaches geared at fixing running injuries.  If after reading this article you disagree or are ‘enraged’ I implore you to ask yourself this question, “Why do I believe that stretching will improve performance or prevent injury”?  Did someone tell me?  Did I read it somewhere, if so, where? Just because we “believe’ something to be so does not make it so. In order to grow we must challenge or own beliefs and opinions.  Only then can we learn and incorporate new techniques into our live and training plans allowing us to become better at what we do.
  1. American Journal of Sports Medicine, Vol 21, Issue 5 711-719 1993.  “Prevention of Running Injuries by warm-up, cool-down, and stretching exercises.
  2. British Medical Journal August 31; 325 (7362): 468.  “Effects of stretching before and after exercising on muscle soreness and risk of injury: systematic review”
  3. October 2004 Biomechanics.  “Stretching, in or out”?
  4. Runners World October 2004.  “Does Stretching Prevent Injuries”?
  5. Journal of Strength and Conditioning Research 2005, 19 (1), 206-212.  “The acute effects of static and ballistic stretching on vertical jump performance in trained women”.
  6. Medicine & Science in Sports & Exercise 2004, 0195-9131/04/3608-1397.  “Effect of acute static stretching on force, balance, reaction and movement time”.