Muscle Stretching. Since the first day of your first physical education class you have been stretching your muscles. Touch your toes. Reach for the sky. Grab a buddy and grab a foot. Pull. Touch your toes again…and so on in perpetuity. Stretching probably isn’t what you’ve always thought it is. As Physical Therapists we hear the same things stated by patients every day “I’ve always been ‘tight'”, “I’m tight so I need to stretch” or “My back hurts, so I was told that I need to stretch my hamstrings”.Is any of this true? Turns out that, for the greater part, it isn’t. Read on for the real story..
What is stretching?
Muscles have ends, an origin and an insertion. For some muscles it is debated which end is which, but for the sake of our discussion it doesn’t matter as long as we identify a difference. Stretching is the act of moving the insertion of a muscle away from it origin. It can be performed deliberately with purpose or by happenstance, i.e. every time you use a muscle, its antagonist will stretch to allow joint motion to occur without jamming up the works. There are many types of stretching: Static (holding the insertion away from the origin for a set time period), Dynamic (repetitively moving the insertion away and toward the origin for a set amount of repetitions or a specific duration), Contract-relax, Ballistic and a few others.
Other tissues of the body sometimes need to be stretched or “mobilized” to increase joint motion. These tissues (joint capsule, ligament, nerve) are not built like muscles, and if they need to be stretched or mobilized then it is likely the result of injury. Your Physical or Occupational Therapist will be your guide as to whether or not this type of stretching is required related to your injury and know how to perform the activity without your hyper-reactive muscles getting in the way.
Stretching muscles likely doesn’t do what you think it does…
If you ask the average person what she thinks muscle stretching does, you will commonly hear answers such as: “It lengthens my muscles”, “It makes me more flexible”, “It helps prevent injury”. A multitude of research on the possible benefits of muscle stretching has been performed, reviewed and re-reviewed over the past 25 years.
The pure research quality of many of these studies varies, but clinically there are several themes that are common and stand out:
1) Muscle stretching doesn’t cause significant or LASTING muscle lengthening.
Muscles at their basest structure are formed of units called “sarcomeres”. These units shorten and lengthen via a series of electrochemical reactions. When grouped together in a row the tiny amounts of movement add up to the full range of motion we see when we contract and relax our muscles. Stretching studies in humans and animals have either shown no increase in the number of sarcomeres in stretched muscles, or have shown that any increase in the number of sarcomeres is balanced out by the shortening of each individual sarcomere unit, preserving the overall length of the muscle being tested.
Muscles follow a property call “viscoelastic deformation”. Muscle tissue is relatively squishy, almost rubbery in nature compared to say, bone or most cartilage tissue, so when it is pulled statically, it tends to increase its length TEMPORARILY. Studies in humans have shown that gains from a stretch of 45 seconds, followed by a stretch of 30 seconds to the same muscle, has no cumulative lengthening effect.
2) Muscle stretching does not improve athletic ability, strength or prevent injury. Wait…Whaaaaaaaat?!?
Yes. The extensive available evidence does not support the hypothesis that any type of muscle stretching has a positive impact on performance or helps prevent injury. In some cases the research has shown stretching to cause DECREASED muscle power and function.
3)Performing warm-up activity, applying heat or other common modalities prior to stretching muscle does not increase the effectiveness or change the measured outcome of a stretch and does not transfer to subsequent stretching improvements.
Research is necessary, but statistical results are not always applicable or accurate for the whole population. In my vast experience being active prior to a stretch is usually much more comfortable for all tissues. In rehabilitation, long-term gains (or what we call carry-over) is not assured and diligence and coherence to your daily home program is imperative to success.
Gains in flexibility are a result of shifting the sensation barrier of the tissue being stretched.
Your nerves both receive (sensory nerves) and send (motor nerves) signals from and to muscles. If you have ever stretched, you know when you have to stop. Does the tissue ever just stop moving, or does it start to hurt? It HURTS. The majority of studies examining the actual causes of increased flexibility have come to the conclusion that any increase in mobility is a result of desensitization of the sensory nerve impulse into the new ranges of motion.
One type of motor nerve works to keep the muscle fibers in a state of readiness to actively contract. Without complicating the explanation too much, these nerves establish a set point at which the sensory system recognizes the feeling of the “normal” length of a muscle. That set point can be shifted so we perceive the muscle in question as feeling tight or feeling loose.
Post-surgical patients often come to us with moderate to severe restrictions in gross joint movement even very soon after surgery. Many are informed post-operatively by the surgeon that a full range-of-motion of the joint was achieved under anesthesia. When you are under general anesthesia, your nervous system is dampened, eliminating pain and reflex activity, so there is no significant neuro-muscular resistance to passive motion. When your body wakes up again and responds to the trauma of surgery it can often re-set the “normal” muscle resting point to a state of moderate to severe hyper-contraction, leading to a shortened and often painful sensation. This is what limits available motion, not actual hard physical restriction. For most people in this situation who have not also experienced shortening/adhesion of the deeper, non-muscular tissue, gentle repetitive movement during treatment with a therapist is enough to re-gain normal muscle mobility without traditional and often forceful “stretching”.
So now I know what stretching is and what it actually does. How do I use that information?
If you do actually need to stretch, learn when it is effective.
There are measurements of joint motion related to muscle flexibility that are considered clinically and functionally normal. Many people have what is considered normal flexibility but insist on stretching–often aggressively, or incessantly demand to be stretched when in treatment. Your therapist has gone through many years of training. Ask questions to stay informed and learn how to care for yourself when healthy, but trust that she knows what interventions are required to get you back on track.
Learn your anatomy to stretch specifically and with purpose.
If you stretch a muscle, you need to know on which structure it starts and on which structure it ends. For example, the most common picture of hamstring stretching I have seen includes either the person pulling on her toes, or deliberately flexing the ankle so the toes point up toward the knee and with the back hunched. This is incorrect and possibly injurious. The hamstrings don’t insert anywhere near the ankle and don’t originate in the spine. If you have certain back issues, that position is very likely to stretch the sciatic nerve rather than muscle, further exacerbating your misery. (Notice in the topic picture all hamstring stretches show a correct, pointed/relaxed ankle and straight or slightly extended lumbar spine.)
Before embarking on a new program, seek advice from a qualified, trusted professional.
Have you ever received an email, or seen a social media post with the title format “Do these (#) stretches to help you (Add part here)”, or “Do these exercises to fix your (insert injury here)”? If you are injured or are currently in treatment for injury do yourself the favor of favors and ask your therapist if those activities are right for you before airing out the old jogging suit and bending yourself mercilessly into a human pretzel.
Muscle stretching! Popular, mainstream, completely misunderstood. There is a time and place for stretching and is not necessary as much as most people believe. It should be comfortable, non-aggressive and aimed toward long-term maintenance of a healthy system. Be informed. Be well.
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