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How to address this trail-injury hotspot

It’s a gorgeous morning and you’re halfway through your run, at the top of a peak, ready to bound down. Relaxed and flowing, you’ve cruised this downhill a hundred times, but lurking is one wonky stride that could change everything. Simply overstriding on a downhill or slipping on uneven ground can exacerbate an already stressed hamstring and cause a strain injury, or worse.

This article appeared in our October 2009 issue.

According to The Textbook of Running Medicine, upper-leg injuries account for about 10 percent of all running-related injuries, and one study reports hamstrings being responsible for 60 percent of all upper-leg muscle strains in runners. However, avoiding hamstring strains is not the only reason why runners should focus on this muscle group—their strength and flexibility are also responsible for maintaining the integrity of the lower back and knees.

Working Knowledge

Understanding the hamstring’s function is necessary for learning how to train them for the rigors of trail running. The leg’s forward swing from the knee down is regulated by lengthening of the hamstring muscles. That means that as you extend your leg until your foot strikes the ground, they lengthen and actively contract at the same time. This is called an eccentric contraction, and is a potentially very stressful situation for the hamstrings.

Another concern for endurance runners is that, of all muscle groups, the hamstrings are the only ones to show significant decrease in strength after long runs, making you more susceptible to injury at the end of big outings.

Researchers at the University of Innsbruck Medical School in Austria revealed that during the Tirol Speed Marathon hamstring peak force decreased significantly and runners experienced eccentric hamstring fatigue. Since eccentric hamstring fatigue is often associated with soft-tissue and knee injuries, training these muscles eccentrically (for lengthening contractions) should preserve their strength and avoid such injury.


Hamstring injuries are best avoided by staying strong and limber. Most runners make the mistake of assuming that because they run, their legs are plenty strong. While your hamstrings may be proficient at propelling you up hills, they are not always in sound biomechanical working order.

Dr. Karl Kozlowski, athletic trainer and director of the Human Performance Laboratory at the University at Buffalo in New York, emphasizes doing heavy leg curls at the gym may not translate well to trail running, because you are exercising the hamstrings in a shortened position. (When your knee is bent, your hamstring is shortened; when it is straightened, it is lengthened.) Since the point where an injury is most likely to occur is when the muscle lengthens, the best way to gain functional strength is to train the hamstrings as they lengthen or are in a lengthened position.

As well as flexing the knee, the hamstrings also help to extend the hip. Therefore, it’s important to also train the gluteal muscles.

Three excellent exercises for building functional hamstring strength are leg curls using a Swiss ball, Nordic hamstrings and single-legged dead lifts (see “Healthy Hamstring Exercises”).

Hamstring flexibility is also paramount to avoiding injuries. Leaning over to touch your toes is not the recommended technique though. According to back-pain specialist Dr. Stuart McGill, bending over to stretch causes too much flexion in the lumbar region of the spine which eventually could rupture a disc. Instead, he recommends the following stretch as safer and more effective.

You’ll need a Thera-Band, old pair of panty hose or a plain ole towel. To begin, lie flat on your back with both knees bent, straighten one leg, loop the stretching aid under your toes and hold an end in each hand. Now, gently raise your leg with your foot flat and knee straight. Hold for 30 seconds then repeat on the other side.

Sometimes even stretching can’t get rid of a nagging twinge or pulling feeling in the hamstrings. When this is the case, consider employing a good massage therapist, or if you’re the do-it-yourself type, try myofascial release, employing a foam roller (looks like thickened pool noodle) or even a tennis ball.  Myofascial release is the manipulation of soft tissue so that muscle fiber and connective tissues reorganize into a more flexible, less painful situation.

To perform the procedure, sit crosswise on a bench or a stool with no back. Place the roller or ball under the knee and roll it slowly up your leg to the buttocks, pausing and working any sore spots. Relax and breathe because it will probably hurt. Do this a few times and in different positions under the hamstring, then finish with stretching.


When you feel a tweak in your hamstring area, how do you diagnose the injury? With acute strains, e.g. resulting from a slip or sudden twinge, there is extreme pain in the posterior of the thigh, and you may even hear a “pop” or experience a tearing sensation.  “Acute strains” refer to the immediate pain in response to injury, whereas “chronic strains” refer to persisting injuries.  Chronic strains may result from acute strains.  In either case with these injuries, pain will intensify when the knee is bent, especially with resistance.


According to Dr. Kozlowski, treatment of hamstring strains is difficult. Muscles heal best when they can remain completely inactive, but basic activities like sitting in a chair cause the hamstrings to contract, resulting in more disorganization within the muscle fiber, increased inflammation and longer healing time.

Kozlowski advises limiting activity and icing for 20 minutes every hour immediately after injury or onset of pain, for the first 24 to 48 hours. Icing the hamstring in the extended position yields the best results and, between icings, wrap the thigh with a neoprene brace or ace bandage to maintain compression.

Once muscle soreness has decreased, Kozlowski advises runners to engage in backward walking for 20 to 30 steps while fully extending the hip and following through with the leg. Since the hamstrings not only bend the knee when contracting but also extend the hip, this technique emphasizes both actions. This is important since any imbalance in the core’s hip stabilizers can cause more strain on the hamstrings group of a particular leg. Additional exercises to strengthen and stabilize core muscles and provide balance should be performed, since weakness in either area can ultimately demand more force from the hamstrings (see “Getting to the Core”).

April Ferrentino is the mother of one, a graduate student in exercise physiology and works as a strength and conditioning specialist. She hits the trails in the Greater Buffalo Area in New York.

Healthy Hamstring Exercises

Single-legged dead lifts

> Stand on one foot, keeping both knees together and not swinging the free leg back.

> Hold a medicine ball, small dumbbells or liter water bottles in both hands. Keeping the back and leg straight, hinge at the hips and lean forward as far as you’re comfortable. Try to touch the ground with the weighty object in your hands, but only go as far as you’re comfortable.

> Begin to stand straight up, bringing the object in your hands all the way over your head. Try to do this without tapping the ground with your other foot. Perform 2 to 3 sets of 8 to 10 reps.

Swiss-ball leg curls

> Lie flat on your back.

> Place your heels on top of a Swiss ball so that your knees are bent to a 90-degree angle.

> Lift your butt off the ground and fully extend your hips.

> Extend your legs all the
way out.

> Bring your legs back to a 90-degree bend.

> Slowly drop your butt back to the floor. Do 2 to 3 sets of 15 repetitions.

Nordic hamstrings
(you may need a partner and a mat)

> Kneel on the floor with your knees on a towel or mat, and have a friend hold down your ankles.

> With your hands behind your head or across your chest, slowly lower your body until you are almost in a lying position (or as far as you can comfortably go).

> Pull yourself back up. Do not bend at the pelvis on the way up or down. Do 2 to 3 sets of 8 to 10 repetitions.

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