Though yogis have been stretching for millennia, much remains unknown about how stretching actually works. A lot of our understanding has been based on tradition, observations, and individual experience, rather than on large-scale studies or measurements of the specific physiological effects of stretching.
In some cases, what we’re finding out about stretching is challenging conventional wisdom.
But recently, more research has focused on what is actually going on in the body when we stretch. This has led to some interesting answers and, at times, more questions. In some cases, what we’re finding out about stretching is challenging conventional wisdom.
Three Types of Stretching
For the discussion below, it is important to understand the different kinds of stretching, as they have slightly different effects. (See questions 3 and 4.) Generally speaking, there are three types of stretching, and we may do them all, to varying degrees, in yoga:
1. static (holding a position)
2. dynamic active (bringing a joint repeatedly through its range of motion)
3. PNF (proprioceptive neuromuscular facilitation, one technique of which requires the contraction of the target muscle when it is stretched, followed by a more passive stretch with the muscle relaxed)
(A fourth type, dynamic ballistic stretching—stretching with a bouncing movement—has fallen out of favor because it carries a greater risk of injury.)
Holding a pose like wide-legged forward fold or figure four for several breaths are examples of a static stretch in yoga. We stretch dynamically when we move between cat and cow, in and out of squats, lunges, or twists, or when we lift and circle a leg from downward facing dog or circle our arms in repeated “quarter sun salutations” when we move from tadasana (mountain pose) to urdhva hastasana (upward salute) and back.
And PNF? One type of PNF technique (“contract/relax”) comes into play when, in a low lunge with our back knee down, we try to drag that knee forward, isometrically contracting the quadriceps for a few breaths before sinking deeper into the lunge to stretch the quadriceps. Or when, in supine hand to big toe pose, we encircle the thigh of our lifted leg with our hands, and press our thigh away from us, against our hands, contracting the hamstrings before drawing the leg closer to our chest for a more passive hamstring stretch.
Now that you know the three main types of stretching (and how they relate to yoga), let’s explore some common questions about stretching, both in and out of yoga practice.
1. What are the benefits of stretching?
Research testifies to the ability of stretching of all kinds—dynamic, static, and PNF—to improve range of motion.
Stretching may also help to relieve pain. For example, both stretching and a regular yoga practice have been shown to ease lower back pain, stretching the neck seems to be about as effective at reducing neck pain as manual therapy, and stretching the Achilles tendon can relieve heel pain. And new research indicates that in the minutes after—if not necessarily during—stretching, there is increased activation of the parasympathetic nervous system (the system in charge of relaxation), which may partially account for the feeling of well-being yogis experience after stretching.
2. Does stretching help prevent soreness and injury?
Maybe a little, but old theories about the positive effects of stretching on muscle soreness and injury are now in question. Some studies have found that stretching, before or after a workout, makes a negligible difference in muscle soreness and that stretching before a workout does not significantly reduce injuries. And yet, in another study, participants categorized as being more flexible—a quality stretching can help to cultivate—experienced less soreness and muscle damage than participants evaluated as being “stiff.” And military basic trainees who underwent a program of hamstring stretching experienced fewer overuse injuries to their legs than those who didn’t.
While it certainly seems that stretching is no panacea for injury or muscle soreness, it would not be correct to say that it is of absolutely no benefit—the research results are mixed.
3. Should you stretch as part of your warm-up?
If your goal is injury prevention, probably not. Stretching before an athletic activity seems not to help prevent injuries, and may, in fact, increase the likelihood of injury, perhaps because it decreases responsiveness to pain or makes muscles less stable.
If your goal is performance enhancement, stretching before the activity may or may not be helpful. It seems that stretching statically before a workout can actually have a detrimental effect on athletic performance, and static stretching has been shown to decrease running speed and jump heights. Like static stretching, PNF stretching demonstrably decreases both strength and power. But if you want to stretch before your workout, sprint, or game, stretch dynamically: Dynamic stretching may improve athletic performance slightly. Six to twelve minutes may be sufficient; longer dynamic stretching routines before an activity could impair performance.
4. Then is dynamic stretching best?
It depends. Dynamic stretching may be best for those who are warming up for athletic activities that require running and jumping (like soccer, tennis, and basketball). But in activities where positions that demand a large range of motion are often held—like gymnastics, wrestling, martial arts, figure skating, and dance—static stretching as part of a warm-up can improve performance when those stretches are bracketed by a few minutes of aerobic activity like running.
Women and older adults over 65 may benefit most from static stretching, while men and older adults under 65 may make more and faster gains through PNF stretching.
5. How does stretching increase range of motion?
As mentioned above, we do know that stretching can increase range of motion; as we stretch repeatedly, we are able to go deeper into certain poses. Interestingly, what is not known is how this occurs.
The common conception has been that we are increasing muscle length—“extensibility”—and that this length is what leads to increased range of motion. But some studies have noticed that muscle extensibility doesn’t change much as a result of stretching and assert that the improvements in range of motion result from stretch tolerance—a participant’s ability to withstand the pressure placed on a muscle.
We know that stretching can increase range of motion. Interestingly, what is not known is how this occurs.
Other research similarly suggests that a modified perception of sensation, not a change in the properties of the tissue itself, allows those who stretch regularly to stretch farther; meanwhile, women with benign joint hypermobility syndrome, who have extremely flexible hamstrings, do not seem to have “longer” muscles or tendons but rather to be more tolerant of sensations that accompany hamstring stretches.
Within the yoga community, interest has been awakened in the role played by fascia (the connective tissue that forms webs around our muscles and other internal structures) in increasing range of motion. But understanding the impact of stretching on fascia, as distinct from the impact of stretching on the muscles themselves, requires more and larger-scale studies than any of those yet done.
6. How often should you stretch?
The American College of Sports Medicine1 makes the general recommendation of static stretching (after an active warm-up) at least two to three days per week, but stretching “dosage” may depend on a variety of factors, including your age, the activities you do, and how tight you feel.
7. How long should you spend in each stretch?
The duration of a stretch that is most beneficial may vary somewhat, depending on your age. One study suggests that holding a hamstring stretch for 30 seconds is more beneficial than holding it for 15 seconds, but the same study points out that holding a stretch longer (up to a minute) led to no further gains in flexibility. However, none of the participants in that study were over 40, and some research is suggesting that for older adults a hold of 60 seconds is more effective.
Tom Myers, author of Anatomy Trains, posits that fascia stretches slowly, and recommends holding for three minutes after the first sensations of release. Since no research yet supports the efficacy of such long holds and injuries can be caused by overstretching, yogis who wish to conduct their own experiments with longer holds might keep themselves safe by keeping their stretches mild, as stretches often are in many yin and restorative yoga practices.
8. How many times should you repeat a stretch?
Practice each PNF or static stretch up to three to four times in one session, since repeating the same stretch in a single session more than four times may lead to no further progress and perhaps make a muscle more vulnerable to injury. Research shows that dynamic stretches can be repeated ten to fifteen times before an activity for optimal performance.
9. So it is not necessary to do any yoga pose more than three times in a single session, or hold any pose longer than a minute unless you are over 65?
Hold on! Yoga is not “just” stretching. Many poses build strength as well as increase flexibility. If your goal is to build strength, it may well be worthwhile to hold some poses longer or do more repetitions, as we do when flowing through the poses of a vinyasa or repeating a sequence of standing poses multiple times.
Yoga is not “just” stretching. Many poses build strength as well as increase flexibility.
10. Can we increase range of motion without stretching?
Research suggests that foam rolling alone, which is said to massage the fascia and of course also massages the muscles and other structures, does improve range of motion, though it is most effective in combination with static stretching, and should be avoided in the case of underlying injuries. Massage therapy has also been shown to increase range of motion, as has Rolfing.
11. How long does increased range of motion last?
In the same study referenced above, static stretching, foam rolling, and the combination of both led to significant gains in flexibility that lasted ten minutes. Another study showed that significant increases in hamstring flexibility after PNF stretching lasted for six minutes. While the most significant increases in flexibility seem to endure no more than fifteen minutes, some gains in hamstring length last for twenty-four hours after static stretching.
The Bottom Line?
You’ll notice the jury is still out when it comes to the efficacy of stretching and the means by which it is effective, nor is there any definitive answer as to what type, frequency, and duration of stretch is best for whom, which means that, in keeping with tradition, we yogis must continue to conduct our own experiments and rely on our own observations. Which type of stretching leads to the greatest gains of flexibility for each of us? How long a hold seems to be the most beneficial? How many days a week does it behoove us to stretch? These answers will vary from individual to individual, and they might vary for each of us over the course of our lives.
1. Medicine ACoS ACSM's guidelines for exercise testing and prescription. 7th ed. Baltimore: Lippincott Williams Wilkins; 2006.