You know that person in front of you waiting for a bus.

She’s got her long legs turned out and she’s pointing and flexing her feet. Maybe her hair is pulled into a tight bun. She’s probably a ballet dancer.

But, seriously, is that necessary?

Actually, yes, according to New York City physical therapist John Lathrop.

“Your body adjusts to what it has to do often,” Lathrop told me in a telephone interview.

“People who do ballet are constantly moving their bodies through extreme ranges of motion and that’s why their bodies stay so flexible.”

For the rest of us who have desk jobs, even short amounts of stretching frequently throughout the day are not enough to prevent hamstring tightness, which is a particular problem if you’re a runner, like me, who uses the weekends to put in some long distance mileage but spends the rest of the week in a car or in meetings, at a computer, or on the phone.

“Ballet dancers get used to being in those positions and their nervous systems tell them that’s where they need to be and that’s their neutral position.”

Lathrop’s spent 15 years working with athletes coming out of injuries – first as a personal trainer and then as a doctor of physical therapy – but his practice in midtown Manhattan also specializes in helping weekend warriors in desk jobs learn how to avoid injury and make the most of their passion for sport after hours.

Poor postural patterns don’t yield good results functionally when we attempt to do our sports or other activities on the weekends that require our muscles to be flexible, Lathrop said, often leading to skeletal muscular strains, which account for up to 55 percent of all sports-related injuries.

Oftentimes it’s an acute strain, or tear, we might have been able to prevent through conditioning and better attention to correct form and to rehabilitating our injuries so we don’t suffer the same strains over and over again.

And knowing when not to stretch.

Here’s why.

Hamstrings 101

The hamstrings are the group of three long, stringy muscles at the back, or posterior, of your legs that move both your hips and your knees, Washington, D.C., physical therapist Kevin McGuinness explained to me after I suffered a high-grade hamstring tear during a training run.

The hamstrings are also known as flexor muscles because of the role they play in bending the knee. Some sources claim European butchers hung the hocks, or hams, of pigs by their stringy muscles in their shop windows. According to Merriam-Webster the word “hamstrung” refers to the inability to move forward, which may have been derived from the Roman practice of slashing through the muscles at the back of the legs as a form of torture or during battle, leaving men or their horses unable to move.

Which also makes sense because the hamstrings are responsible for deceleration and they literally work to stop your legs as you move forward. The hamstrings are partners with the quadriceps, the group of muscles on the front, or anterior, of your legs, so whenever your legs are moving, both have a job to do, McGuinness said.

In fact that’s one of the reasons why running places such a high demand on the hamstrings and why hamstring injuries are so common in all sports that incorporate some form of running, McGuinness noted. While the hamstrings and quads need to work together, the hamstrings are vulnerable because by comparison, they are much smaller muscles than the quadriceps yet have the powerful responsibility of controlling both the hip and the knee.

And then there are the gluteus, or gluteal, muscles, the ones we sit on when we’re at our desks. According to Lathrop, we need our gluteal and quadriceps muscles to absorb the shock and also to stabilize our pelvis and lumbar spine when we run, but when desk workers lose control of their gluteus muscles, they often compensate with the hamstrings, which aren’t a strong muscle group compared to the gluteals either.

“The hamstrings have their job to do but if the glutes are not doing theirs, straining or tearing the hamstring can become an almost repetitive overuse injury,” Lathrop said.

Some Hamstring Tears Are Good, Others, Not So Good

If you exercise regularly you know from your training that in order to progress you need to place an appropriate amount of stress on your muscles and then give them time to adapt to the stress. So in reality our muscles suffer millions of tiny tears all the time, and that’s good.

Yet as in all overuse injuries, small tears can lead to big tears, Lathrop noted, partially because as you continue to strain the hamstring muscles, your body’s protective mechanism is to tighten up the hamstrings to prevent them from further injury. If you try to stretch the muscles, they will essentially fight back by getting even tighter.

And feeling tighter, added McGuinness, who noted that “tightness” could be a symptom that doesn’t always correlate with hamstring flexibility. If the hips are tilted forward, for example, which could be the result of poor hip or lower back mechanics (perhaps from poor sitting posture), the hamstrings will feel tight even if they have normal length, he said.

When we’re sitting at our desks, we’re keeping the knee and hip flexed for long periods of time, and as a result, this becomes our neutral position, which is the opposite of what we need to be doing when we’re running, McGuinness said.

“Running requires the hip and the knee to alternately flex and extend.”

Rehabbing Hamstring Tears

Mild hamstring strains, where only a few muscle fibers tear, heal on their own within a few days, McGuinness said.

But after hearing and feeling my hamstring “pop,” I was pretty sure I was headed to surgery with some significant time away from running. I figured whatever ripped would need to be pieced together or replaced with healthy tissue from another part of my leg.

Yet unlike common muscle injuries involving the shoulders or the knees, for example, physicians do not typically recommend surgery for hamstring tears, McGuinness said.

Even where tendons separate from the bone, which is what happened in my situation, the body has an ability to fill in the gap created by the injured tissues with a collagen fiber matrix, commonly referred to as scar tissue, and to hypertrophy the remaining muscle, or to increase the size of the healthy muscle through exercise and strength training, McGuinness said.

“Once you tear a hamstring, it will never heal the way a cut heals,” McGuinness said, but the area fills in with connective tissue and scar tissue, which is stretchy and strong even if it doesn’t actively contract like muscle tissue.

While the complete process can take up to 18 months, most people can return to running within three to 12 weeks. Although that’s a long time for a competitive athlete, for a weekend warrior, even though we may need to run at a slower pace and reduce our weekly mileage, that’s pretty good news.

It’s important to get back to running, McGuinness noted, because you want the scar tissue to begin to grow in the right direction, and you need to apply stress to the remaining muscle so it can hypertrophy, or in other words, get bigger and stronger in order to do the work of the missing, or damaged, muscle tissue.

Without stresses the muscle is never going to regain strength and flexibility, McGuinness said, and tensile integrity, or how much your muscle is able to stretch, can become a chronic problem.

Preventing Hamstring Injuries

One way runners can protect themselves is by working on hamstring strength as well as flexibility, McGuinness said. Usually this would mean incorporating eccentric exercises, which strengthen the hamstrings as they contract. Examples would be running downhill or squatting with weights.

Another way is for runners to shorten their stride, he said.

And instead of passively stretching and flexing your muscles in meetings or anyplace else where it doesn’t make sense for you to tendu, both Lathrop and McGuinness encourage runners to incorporate core muscle exercises and hip stabilizers in order to work muscles underused in running. That’s in addition to getting up and moving around frequently throughout the day so you’re not sitting or standing for extended periods of time.

Most important, Lathrop said, is to prepare your body every time you go out for a run.

“So many times people have 30 minutes to work out and they don’t want to sacrifice the main purpose of their workout so they avoid the warm up and cool down.”

The purpose of warming up before you exercise is to increase tissue temperature for better extensibility and injury prevention, said Lathrop, who recommends taking your body into active stretching by mimicking the movement that is going to be performed, for example, walking before running.

After exercise, you want to do the reverse to gradually cool back down, and then finish with gentle, passive stretching, he said.

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