Two views on stretching, from our experts Dr. Mirkin and Coach John Hughes.
Stretching Doesn’t Help
By Gabe Mirkin, MD
Extensive Research shows that stretching:
* does not lengthen muscles (Clinical Biomechanics. June 2014;29(6):636-642),
* does not prevent sports injuries (Clinical Journal of Sports Medicine, March 2005),
* does not prevent muscle soreness that follows vigorous exercise (Cochrane Database of Systematic Reviews 2007, Issue 4),
* decreases muscle strength when done before competition (Journal of Bodywork and Movement Therapies, April 2006),
* limits how fast you can run (The Scandinavian Journal of Medicine and Science in Sports, April 2013, & Sports Science, May 2005), and
* limits how high you can jump (The Journal of Strength and Conditioning Research, April 2013).
Stretching Does Not Lengthen Muscles
You can make a muscle longer while you are stretching, but after you finish stretching, the muscle returns to its former length. People who stretch regularly, such as gymnasts and people who do yoga, can stretch further than non-stretchers because they can tolerate more pain while they stretch. Stretching a muscle pulls on nerve fibers in the muscle to cause pain, so you stop stretching when it hurts. When a person is given an anesthetic, he can stretch much further because he feels less pain. Regular stretchers stretch so often that they feel pain later than non-stretchers do and they learn to tolerate more pain when they stretch.
If muscles did remain stretched, stretching would harm you because the overstretched muscle would lose its elasticity and be much weaker. Placing animals in muscle-stretching casts for several weeks can cause the muscles to grow extra units called sarcomeres, but muscles return to their original length soon after the cast is removed.
How Muscles Move Your Body
Every muscle in your body is made up of thousands of individual fibers. Each muscle fiber is composed of sarcomeres; repeated similar blocks, lined end-to-end to form the rope-like fibers. Each sarcomere touches the sarcomere next to it at the Z line (see diagram). Muscles move your body by contracting, which shortens each muscle fiber. Muscles do not shorten (contract) equally throughout their lengths. Muscles contract only at each of the thousands of sarcomeres. It is the cumulative shortening of thousands of sarcomeres that shorten fibers to make muscles contract and move your body.
The Chemistry of a Muscle Contraction
Look at diagram below. This is the chemical structure of a sarcomere. A sarcomere contains two chemicals: actin and myosin. The actin chemicals line up between myosin chemicals above and below them. The actins slide toward each other to shorten the sarcomere. When thousands of sarcomeres shorten together at the same time, the entire muscle contracts.
Stretching Does Not Prevent Sports Injuries
Muscles and tendons tear when the force applied to them is greater than their inherent strength, so anything that makes a muscle stronger helps to prevent injuries. Lifting weights prevents injuries by making muscle fibers stronger. Stretching does not strengthen muscles so it does not prevent injuries such as shin splints, bone stress fractures, sprains or strains.
Stretching Does Not Prevent Next-Day Muscle Soreness
A review of 12 studies published over the last 25 years shows that stretching does not prevent muscle soreness that occurs eight to 24 hours after you exercise vigorously (The British Journal of Sports Medicine, December 2011; 45:15 1249-1250). Researchers in Australia reviewed five studies, involving 77 subjects, to show that stretching does not prevent next-day muscle soreness (British Medical Journal, December 2007; 325:468-70 and 451-2).
To enlarge a muscle and make it stronger, you have to put enough force on it to feel a “burn” during exercise and damage that muscle. That is why proper training requires some degree of muscle soreness on the day after an intense workout. Athletes train by taking a hard workout, feeling sore the next day, and then taking easy workouts for as many days as it takes for the soreness to go away. Since stretching does not reduce muscle soreness, stretching will not help you to recover faster from hard exercise. The best way to recover from exhausting competition is to move with little pressure on muscles, such as cycling at a relaxed pace (American Journal of Physical Medicine & Rehabilitation, June 2007).
Stretching Before Exercising Weakens Muscles
Elite college sprinters were timed in 20-meter sprints, with and without prior multiple 30-second stretches of their leg muscles. Both active and passive stretching slowed them down (Journal of Sports Science, May 2005). Stretching before competition or training weakens muscles. Stretching prevents you from lifting your heaviest weights or running your fastest miles. It limits how high you can jump, and how fast you can run (Scand J Med Sci Sports. 2013 Mar;23(2):131-48 and J Strength Cond Res. 2013 Apr;27(4):973-7).
Stretching weakens muscles temporarily by almost 5.5 percent. The longer you hold the stretch, the more strength you lose. Holding a stretch for more than 90 seconds markedly reduces strength in that muscle. Stretching reduces power: how hard you can hit a baseball or tennis ball, or how fast you can swim, run or pedal. When you stretch a muscle, you pull on the muscle fibers and stretch apart each fiber at the thousands of Z lines. This damage occurs only at the Z lines throughout the length of the muscle fiber, to weaken the entire muscle. On the other hand, warming up makes muscles more pliable, so it helps you to run faster and lift heavier, and to prevent injuries.
Stretching Does Not “Warm Up” Muscles
Stretching can never be considered “warming up.” Holding a muscle contraction does not generate much heat and therefore does not warm up muscles. Warm up by starting out your exercise slowly and gradually increasing the intensity. This raises muscle temperature to make muscles more pliable and resistant to injury. Since almost 80 percent of the energy used to power muscles is lost as heat, you must contract and relax muscles continuously to generate the heat necessary to raise muscle temperature.
Prolonged Stretching Limits the Ability of Muscles to Store Energy
Muscles are like rubber bands. They stretch and contract with each muscle movement. This constant stretching and contracting stores energy. For example, when you run, you land on your foot and the muscle stops contracting suddenly. The force of your foot striking the ground is stored in your muscles and tendons and this energy is released immediately to drive you forward. Your foot hits the ground with a force equal to three times your body weight when you run at a pace of six minutes per mile.
Up to 70 percent of the force of your foot strike is stored in your Achilles tendon and other tendons. This energy is released by your muscles and tendons to drive you forward for your next step. Stretching decreases the amount of energy you can store in muscles and tendons and therefore weakens you. You have less stored energy to drive you forward, so you have to slow down.
Proprioceptive Neuromuscular Facilitation
After reading all these negative remarks about stretching, you may ask if there is any good scientific data to show that stretching can benefit exercisers. Good data show that athletes can become stronger by stretching their tendons before they contract a muscle. The longer a tendon, the greater the torque the muscle can put on a joint, and the more force it can generate to make you faster and stronger. Passive stretches do not do this. It is more effective to try proprioceptive neuromuscular facilitation (PNF), in which the athlete stretches his tendons and then tries to contract the muscles from the lengthened position.
Gymnasts have been shown to increase their flexibility more after PNF stretching than after static stretching (Journal of Sports Medicine and Fitness, December 2014). In fact many athletes incorporate plyometrics into their training programs. For example, they jump off a series of steps consecutively. Their leg tendons are stretched when they land and they contract their stretched muscles to do their next jump. However, this has been shown to increase their chances of injuring themselves.
Gabe Mirkin, M.D., is a sports medicine doctor and fitness guru. A practicing physician for more than 50 years and a radio talk show host for 25 years, Dr. Mirkin has run more than 40 marathons and is now a serious tandem bike rider with his wife, Diana. His website is http://drmirkin.com/. Click to read Gabe’s full bio.
Why Stretching May Help You
Note the title of this piece “Why Stretching May Help You.” Each cyclist is an experiment of one with different goals, and different strengths and weaknesses. That’s what makes coaching interesting!
As a coach I look holistically at all the variables that will help a cyclist reach that person’s goals. I stay current on the latest research, but I also interpret that research carefully to see if it is or is not applicable to a specific client.
My client Jay’s areas to work on are different from Ellen’s. Jay’s goal is an age-group medal in the time trial. Ellen’s goal is to complete a century. Jay doesn’t even come close to touching his toes. If he were more flexible, then he could ride with a flatter back, be more aerodynamic and go faster. Ellen can put her palms on the floor and stretching isn’t necessary for her performance, but she has a weak core, so core strength exercises are important.
My oldest daughter is a resident at St. Joseph Hospital in Denver. She’s taught me to interpret experimental results carefully to see if the claimed result is a) valid and b) applicable. A study published in the BMJ (British Medical Journal) examined claims made by the popular TV M.D. Dr. Oz. The study concluded that only 46% of his recommendations were valid! (BMJ, December, 2014) Just because an expert—including me—tells you something, test it and verify if for yourself.
Scientific Experiments Test Specific Hypotheses
A scientific experiment is designed to test a specific hypothesis. For example, does pre-exercise stretching have any effect on maximum power? A study of elite college runners concluded that both active and passive stretching before sprinting slowed them down. (Journal of Sports Science, May 2005).
What if the experiment is whether riding with a flatter back reduces drag and increases time trial speed? Yes, a flatter back improves aerodynamics and has a positive effect on speed. A flatter back is the result of improved flexibility.
How does this apply to Joe, whose goal is to go as fast as possible? From the first experiment we conclude that he shouldn’t stretch before a hard training session or race. From the second experiment we conclude that he should stretch almost daily at some other time to improve his flexibility and performance.
If you do a hard ride to build power or speed, then you suffer micro-tears in your muscles, and stretching won’t help to repair these tears. Does this mean that stretching should never be part of a recovery program? Ellen is training for endurance, and riding at a conversational pace she does little muscle damage. She is stiff the day after her long ride, and stretching will relieve the stiffness so that she a) feels better, and b) can resume training sooner. For more information on stretching and recovery see my eArticle Optimal Recovery for Improved Performance.
In most cases stretching helps my clients. Here’s how:
More Power. One of the reasons that Fabian Cancellera is so fast is because of his flexibility (which is partially hereditary). He can place his hands flat on the floor behind his heels! Because of his flexibility he can rotate his pelvis farther forward when time trialing. This allows him to use his gluteals more (big butt muscles) to get more power. Even if you don’t race, making better use of your glutes will make you a better climber, for example.
More aerodynamic. Only two of my clients (one is 74 years old!) time trial, but all of my clients ride in the wind. Greater flexibility improves their ability to stay in the drops.
More on-the-bike comfort. Most of my clients are endurance riders. In their events they ride against the clock and the clock doesn’t stop when they’re off the bike. Improved comfort means less time off the bike. Try this experiment: Stand bent over about 45 degrees with your hands on a table and with your back arched just a little. Lift your head to see ahead and note how much you use your neck muscles. Now flatten your back and notice how your head rises and visibility improves without muscle fatigue!
Relieve ride discomfort. One of our last warm days in Colorado I climbed for three hours up a canyon. My back got tighter and the last half-hour my glutes were screaming. At home I do the cat stretch on my hands and knees, alternating arching the back and then pushing my stomach down to bend the back the other way. Starting back down the canyon I did the same stretch on the bike (always looking ahead!) and, other than those pesky glutes, had a pain-free, enjoyable ride home.
Faster return to training. After dinner while watching TV I stretched for about 10 minutes, paying particular attention to my glutes. The next day my glutes had loosened up enough that I could ride again with pleasure.
Wait a minute, you say. Research shows that stretching doesn’t lengthen muscles or tendons. How can it possibly improve flexibility?
Try this experiment: stand, stretch your arms overhead and interweave your fingers so that your palms are facing the ceiling. Slowly bend at the waist, moving your hands toward your toes. Just stretch until it feels tight, not until it starts to hurt. Hang there for a count of 10, then straighten back up. Do this a half-dozen times.
Are your hands getting closer to the floor? The first time you bent over you went as far as your normal range of motion, but your muscles were still partly contracted. Those six repeats reduced how much your muscles were contracted and increased your range of motion.
Stretching also helps:
Restore range of motion. When you ride, your feet make circles, with your legs going through a limited range of motion, neither fully extending (except when climbing out of the saddle) nor fully flexing. As a result, your muscles get tight and you lose range of motion. Stretching returns your partially contracted muscle fibers to their normal extension.
Dealing with cramps. Research suggests that muscles that get accustomed to being shorter are more vulnerable to cramping, i.e., muscles that aren’t stretched and are exercised in a shortened position like riding. You can reduce the probability of cramping by stretching regularly. If you cramp, stretch gently to relieve the cramp and then move the affected muscle gently through its range of motion without making it work enough to cramp again. For more information see my eArticle Preventing and Treating Cramps.
Prevent overtraining. Research with Nordic skiers shows that the best indicator of potential overtraining is the skier’s attitude. Is the skier excited about training the next day? Or dreading it?
As reader Neil Taylor suggested in his remarks about stretching, stretching just plain feels good and improves one’s mood! By letting go physically and letting a muscle loosen up, one can also let go mentally, which may reduce anxiety about training. And if you’re not stiff when you roll out of bed, you’re probably more excited about getting on the bike again.
Aid activities of daily living. I’m 65, and most of my clients are in their 50s, 60s and beyond. We have twin goals: to continue to do the sports we love and to continue to live healthy, normal, active lives for as long as possible. The normal condition for most muscles is to be partially contracted. When you are sitting down, your arm and shoulder muscles aren’t at full extension. While writing “Distance Cycling,” I spent too many days and hours working on the computer. My upper body got so tight that I couldn’t reach the pretzels on the top shelf in the kitchen! Stretching helped.
Reduce day-to-day discomfort. When you are sitting, your hip flexors are partially contracted. (They’re the muscles you use to raise your leg.) We all sit too much and, unless stretched, partial contraction becomes the normal position for our hip flexors. This pulls the back out of alignment, resulting in low back pain. You know you need a strong core to hold your pelvis in the proper position. But tight hip flexors and strong core muscles are pulling your pelvis in opposite directions! Both core strength and flexibility are necessary for a healthy back.
Aging gracefully. Falling isn’t graceful! Chronic upper body tightness results in poor posture. Poor posture results in poorer balance. Falls are the number one accident for us older folks!
Part of aging for most people is losing range of motion, another example of “use it or lose it.” The American College of Sports Medicine recommends doing some form of flexibility exercise at least twice a week.
When should you stretch?
The purpose of a warm-up is to raise the temperature of your muscles. Most forms of stretching aren’t active enough to do that and may reduce peak muscle power. Coach Dan Kehlenbach’s Dynamic Flexibility Training for Cyclists does raise the temperature of your muscles and is an effective warm-up, as is moderate-intensity riding.
Why do most pros stretch before a competition? Don’t their trainers know better? They stretch just enough to be sure that they have normal range of motion, and then exercise more vigorously to warm their muscles.
Stretching after you get off the bike will relieve immediate muscle tightness, but won’t prevent Delayed Onset Muscle Soreness (DOMS), the way my glutes felt the day after the hard climb. It it’s convenient, stretch while having a post-ride recovery snack. But if you don’t have time, don’t worry; you can stretch later.
Thinking holistically, the purpose of stretching is to increase flexibility. Since that’s the goal, when you should stretch is pretty flexible (pun intended). In general it’s easier to loosen up your muscles when they’re warm, so stretching later in the day is better than with your first cup of coffee. I know that, but I still usually stretch with my coffee because that’s a convenient time for me. Some is better than none!
How should you stretch?
Many of us remember Bob Anderson’s classic book, “Stretching,” and have an image of sitting on the floor bent forward and holding a stretch for at least 30 seconds. That’s static stretching.
There are many modalities of stretching represented among RBR authors: static stretching, Kehlenbach’s Dynamic Stretching, Alan Bragman’s Active Isolated Stretching, Joe and Maria Kita’s Yoga. Using a hard foam roller on your muscles and massage also relieve tightness and improve flexibility.
Which one is best? Remember the second sentence of this article? “Each cyclist is an experiment of one with different goals, and different strengths and weaknesses.” The answer is: Whichever form of stretching that you like, works best for you, and that you will actually do!
Every one of my clients, if he or she stretches regularly, improves flexibility. For all of the reasons noted above, increasing your flexibility will both make you a better rider and a healthier person.
David wissmar says
Dr Ferran did 17 Iron mans, and forty marathons he was an air force doctor who had a practice in Kona. He was known as the Iron doc.
Two quotes; “Cardiovascular comes back quick, but flexibility takes forever, if time is limited stretch.”
“David there are two kinds of cyclists, those that have crashed and those that are going to crash”
His Obituary had an old picture of him in his fifties, half split shorts, no shirt, running was his meditation.
Chuck Matson says
I’ve been puzzled by Dr. Mirkin’s stance on stretching for quite a while now. His statement that the reason practitioners of yoga can stretch further because they can handle more pain is simply not true. I have been practicing yin yoga for several years now and have noticed remarkable changes in my long-term flexibility I.e., not just for a short period of time after completing my yoga routines. BTW, yin yoga is a form of yoga where stretching poses are held for several minutes at a time without motion. Anyway, I now have a flat back when riding. I can put my hands on the floor (without pain) whereas before I could only touch my ankles. My lower back pain and spasms have completely disappeared. I have much more mobility in my neck. Etc., etc. I have been doing strength training for two decades, but only when I began yoga did these improvements manifest themselves. So why the negativity toward stretching/yoga?