By Adam St. Pierre
CTS Ultrarunning Coach
“Make sure you stretch before you run.”
“Never stretch before you run, but always stretch after.”
“Do some dynamic stretching before you run, and static stretch after you run, but never ballistic stretching.”
There are a lot of ideas about stretching floating around the endurance running ether… let’s address some and help you make the decisions that are right for you.
How Muscles Stretch
Let’s start with some basics on muscles. Muscles are made up of long fibers. Within the fibers there are contractile units called sarcomeres. When a muscle contracts, the length of each sarcomere shortens. The shortening results from the interaction between two types of filaments within the sarcomere, a thick one called myosin and a thin one called actin. At rest, myosin and actin filaments overlap, but not completely. When a muscle contracts, myosin and actin slide over each other, pulling the ends of the sarcomere toward each other. The muscles then pull on the skeleton to create forces that move the body. Muscles always pull, they do not push. Within the muscle there are also Golgi Tendon Organs. GTOs monitor the length of the muscle relative to its maximum length and quickly activate a shortening reflex when a muscle reaches nearly its maximal length, in an effort to prevent muscle damage.
Short hamstrings and calves are known to correlate with good running economy, meaning they allow you to run at a certain speed with lower energy expenditure. It is thought that having short hamstrings and calves (with long Achilles tendons) allows a runner to store elastic energy from each landing that can then be utilized when the runner next pushes off. However, if your calves and hamstrings are so short that they impede the range of motion necessary for your preferred running speeds, then it may be worthwhile to sacrifice some potential elastic energy return in favor of running with less mechanical strain on your muscles.
Static stretching is the technique of creating a scenario that puts a muscle in its fully lengthened position and holding the muscle under tension for a period of time. (The period of time to hold a stretch for is also a subject of debate, from as little as 20 seconds, to 2 minutes or longer… more on this later). After some time the GTOs relax and allow the muscle to get a little longer. Regular static stretching can increase the actual length of a muscle. The question is: Do longer muscles lead to reduced chance of injury and/or improved performance?
As of now, no studies have conclusively shown that stretching improves performance or reduces injury rates. That being said, studies on stretching are notoriously difficult to perform and the methods studied over the years make study-to-study comparisons difficult.
Studies have shown that static stretching prior to power or explosive activities can inhibit performance. For instance, static stretching reduces your maximum vertical leap and the amount of weight you can lift. This may make static stretching detrimental prior to training/competition for power lifters and high jumpers, but what about endurance runners?
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Running requires a joint to move through a range of motion (ROM). Speed and terrain will dictate how large that ROM needs to be. If a runner’s muscles are of sufficient length to permit adequate ROM for running, then static stretching may be a waste of time for that runner. However, if a runner’s fitness improves to a point where he or she wants to run faster, they may need to add some static stretching to achieve a greater ROM to run faster paces.
Dynamic stretching is the technique of moving a joint through a range of motion greater than necessary for a given activity, in a controlled fashion. Leg swings, skips, and a variety of other movements can be done prior to running to prime the joints of the hips, knees, ankles, and shoulders for the movements they undertake while running. While studies have not conclusively shown dynamic stretching to reduce injuries or aid performance, studies have also not shown that dynamic stretching prior to exercise is bad for performance like static stretching can be prior to some sports! Dynamic stretching pre-run is very in vogue for many coaches, trainers, and physical therapists right now, but there’s no evidence in current research that it does anything. However, there may be some value to dynamic stretching as far as “running form drills.”
Ballistic stretching is holding a muscle near its fully lengthened position then “bouncing” to get a little more length. Did anyone else ever have a Phys Ed teacher remind them not to bounce while stretching before Gym class? The difference between ballistic stretching and dynamic stretching is that dynamic stretching lengthens the muscle through its natural range of motion, whereas ballistic stretching bounces the muscle past its natural range of motion. This type of stretching increases the risk of injury without much or any increase in effectiveness, meaning there’s not really a good reason to do it.
Proprioceptive Neuromuscular Facilitation (PNF)
There are a number of techniques for PNF stretching, but the most common one is “contract-relax”. This is when you put the muscle you want to stretch in a lengthened position and then execute an isometric contraction (increased tension with no change in muscle length) for 5-15 seconds. At the end of the contraction you relax the muscle and a partner or immobile object assists in creating a deeper stretch. PNF stretching leverages the interaction between muscle spindles (the parts that regulate contraction) and the GTOs (the parts that regulate relaxation). The contraction increases tension on the muscle more than the lengthened position alone. GTOs respond to tension, so increased tension leads to more GTO activity to reduce the tension by lengthening the muscle.
PNF stretching can be effective for increasing ROM, but unlike dynamic stretches which are recommended immediately prior to activity, PNF stretching is typically recommended as a post-exercise stretch or used in a clinical environment, like a physical therapist’s office.
A few caveats:
Stretching a sore muscle. Many runners will notice a sore spot and stretch it post-run. In the event that the sore spot is a small strain or tear in the muscle fibers, then stretching the muscle can actually worsen the injury. Stretching a tight muscle is okay; stretching an injured muscle is not. If the soreness or pain came on quickly, it is likely related to injury and I would caution you to avoid stretching it for a few days. If you are sore the day following a long run or hard workout, then stretching is fine (though it hasn’t been shown to reduce Delayed Onset Muscle Soreness (DOMS)).
Stretching your calves. Tight calves can manifest as pain in the Achilles tendon, a thick band of tissue that connects your calf to your heel. Uphill running requires a greater dorsiflexion than flat running (you need to pull your toes up higher to clear the ground on uphills than flats), and leaves some people with sore calves, and sore tibialis anterior (muscle on the front of the shin). Regular calf stretching can diminish the pain, but stretching your calves also puts strain on the Achilles tendon. You may not want to stretch your calves until the soreness in your Achilles subsides.
Stretch and strengthen to fix imbalances. The most commonly stretched muscles for runners are the hamstrings, calves (gastrocnemius and soleus), quads, glutes, and hip flexors. All of these muscles are used extensively in running, and imbalances between their lengths and strengths can affect your running stride. Address these imbalances with a personalized and targeted stretching and strengthening program as needed, likely with the help of a physical therapist, but if you aren’t having any issues then you might be better off devoting the time you would spend stretching to running!
Stretching or No Stretching?
So what should you do? If you enjoy stretching, then do it. Stretching immediately prior to high-intensity activity may inhibit performance, but throughout the days, weeks, months, and years of your athletic career stretching doesn’t appear to diminish performance. Immediately prior to high-intensity running workouts, some dynamic stretching to move muscles through their range of motion is a good idea. Stay away from ballistic stretching because the reward isn’t worth the risk. There is very little known risk to performance from stretching immediately post-run, and it can be a useful part of an athlete’s post-workout routine, regardless of whether it acutely helps muscles. And finally, PNF stretching can be effective for increasing range of motion long term, but it’s typically part of a larger physical therapy program.