The hamstring strain is considered to be one of the most common injuries in athletics. It seems like you’re always hearing about a professional NFL or soccer player with a pulled hammy on ESPN. Research shows that depending on the sport, you’ll find hamstring stains can accounts for 8% to 25% of all reported injuries.1
If you’ve ever had this injury, you also know it can be one of the most stubborn. In fact, once you’ve had one hamstring strain your chances of sustaining another are very high.1 Research has shown athletes are between 2 to 6 times more likely to suffer a recurrent strain within 8 weeks of the first.2-6 Strength and conditioning coach Eric Cressey compared the hamstring strain to a crazy, unpredictable mother-in-law writing, “just when you think you’ve finally won her over, she brings you back down to Earth and reminds you how much more she liked your wife’s old boyfriend.”6
While the prevalence of hamstring strains while barbell training or competing in sports like weightlifting, powerlifting or CrossFit may not be nearly as high as those seen in football, soccer or track & field, they sill occur and require our attention.
How Does the Injury Occur?
Most experts agree hamstrings strains happen while sprinting. If you want to get into the exact science, the actual muscle tear often occurs at the end of the “swing phase” of the running cycle.11 This is when the leg is moving or “swinging” from behind the body to the front. During this time the action of the hamstrings is rapidly transitioning from slowing down the forward moving knee to preparing the body to propel itself forward as soon as the foot hits the ground. This quick change from a eccentric (muscle lengthening under tension) to a concentric (muscle shortening under tension) action is thought to be when the muscle is most susceptible to injury. During this terminal swing phase, the hamstring is lengthened quite a bit while experiencing a large amount of force.
As soon as this injury occurs, you’ll know. It feels like a sharp pain in one specific part in the back of your thigh. You’ll instantly have pinpoint tenderness and pain usually where the muscle meets the tendon (the thicker rope-like part of your muscle).
Those who have sustained a hamstring strain will usually have pain with these two tests. The first is called “resisted prone knee flexion”. Lay on your stomach with your knee bent at 90 degrees. Try to hold this position while a friend applies pressure to your foot (in an attempt to straighten your leg).
Next, you may also have pain with a “passive straight leg raise” test. Lie on your back and let your legs hang loose. Have a friend lift your leg up while keeping your knee straight. This test is positive if it elicits pain in the hamstring. This is because the stretch increases tension on the injured tissues.
A hamstring strain can be graded into 3 degrees.
1st degree: only a few muscle or tendon fibers are torn. There may be a small amount of swelling and discomfort. Usually associated with minimal strength loss. You’ll likely be able to walk directly after the injury. Sprinting however will elicit pain.
2nd degree: a partial tear of the fibers. There will be a significant loss of strength and a good amount of pain. You’ll likely have some pain when walking.
3rd degree: a compete rupture of the muscle/tendon. This will be associated with a huge loss of muscle function, often an inability to walk due to pain and massive bruising on the back of the thigh.
The 5 main risk factors people associate with hamstring strains are flexibility, strength, age, sport choice and previous history of the injury. Let’s quickly cover each and whether or not each has any legitimacy.
1) Hamstring flexibility has not been shown in research to be significant risk factor for developing a muscle strain. This means a program of endless hamstring stretches likely won’t cut down your chances of sustaining this injury. However, there is actually some evidence that the flexibility of your other thigh muscles (quads) can play a role. One group of researchers found that athletes with more quad flexibility (as assessed with the Thomas Test) were 70% less likely to suffer a hamstring strain.7
2) The strength of the hamstrings is also a factor that doesn’t have a ton of research behind it. There are however some researchers that say weak hamstrings or muscle strength imbalances (hamstring vs quad) can play a role. The thought process is that if the quads are extremely strong compared to the hamstrings, there will be a ton of force driving the leg forward during the swing phase the running cycle. This would therefore place increased demands on the relatively weak hamstrings to decelerate the fast moving leg and possibly lead to injury. Unfortunately, there are not many studies to back this idea up. Although it’s never a bad idea to strengthen the hamstrings as most athletes over train their quads and have undeveloped glutes/hamstrings. Overall this is a factor with a lot of conflicting opinions.1,3,8,9
3) Age has been shown to be a significant risk factor for developing a hamstring strain.1 Some research has shown that athletes over the age of 25 are between 2.8 and 4.4 times more likely to suffer this injury.4,7 Basically the older you are, the higher your odds.
4) Like I mentioned earlier, research has shown that an overwhelming majority of strained hamstrings occur while running.10 This is a big reason why hamstrings strains rarely occur when participating in the classical barbell sports of weightlifting and powerlifting. However with the popularity of CrossFit, hamstring strains are not uncommon due to the sprinting in training sessions and competition.
5) As with most injuries, athletes with a history of a previous hamstring strain have been shown to be between 2-6 times more likely to suffer another one in the future.1 This is by far the biggest risk factor.
Rehab Phase 1 (Early contraction, maintain mobility but don’t stretch!)
If you have suffered a low-grade 1 strain of the hamstring, here is some practical advice that may be helpful. If you have sustained what you think may be a grade 2 or 3 injury, it is recommended that you go see a medical practitioner for some hands on help in the rehabilitation process. None of the following exercises should elicit pain or make symptoms worse. Also, rest from any painful activity is important. If you have any pain with sprinting, you should absolutely hold all plyometric activities until pain decreases. Without activity modification/rest, rehab will be less effective.
In the past many in the medical community treated hamstring strains with a program consisting of stretching and strengthening. However, what I’ve found working with athletes at Boost Physical Therapy & Sport Performance is that a more functional rehabilitation plan can allow for a quicker return to sport with less chance of sustaining another injury.
In fact, recent research has supported this idea. In 2004 a study came out showing that athletes in a more functional program (consisting of progressive agility training and core stability exercises) showed zero recurrent hamstring strains in the weeks following the return to their sport compared to ~55% of those the “traditional” group who stretched and performed isolated hamstring strengthing.12
During the first 2 days following a hamstring strain, the last thing you want to do is stretch your injured muscles. This will only make things worse! If you feel you need to take a day or two off due to pain, that’s okay. But in order to return to your sport you need to get up and moving to help the injury heal. For this reason, our goal in the first few days is to get that muscle to start working again, but in a pain free and safe way.
Warming-up properly before performing these rehabilitation exercises is key. At home, you can start off with some low-intensity side stepping (~25-50 ft) and some forward and backward steps over a taped line on the ground while moving sideways.12
One of the first exercises I use in the treatment of a low-grade hamstring strain is a bridge. Start by lying on your back with your knees bent. Drive your heels into the ground and brace your core (like someone is going to punch you in the stomach). Next, lift your hips from the ground and squeeze your butt muscles. Hold this for 5 seconds before returning to the starting position with your back flat on the ground. You don’t want to overstress the healing tissues, so if this is painful, stop.
Recommended sets/reps: 2-3 sets of 20 reps for a 5 second hold
I am also a fan of working on single leg balance at this time. Stand on one leg, perform a small hip hinge and try to hold this position for 10-20 seconds. Start with your eyes open and work to progressing this with your eyes closed. You can also do this exercise without shoes for an added stability challenge (remember to work on keeping an arched ‘tripod’ foot with your big toe planted into the ground the entire time!)
Recommended sets/reps: 2 sets of 10 reps for 10-20” holds
The last early-phase exercise we can perform is a lateral band-walk. Exercises in a side-to-side plane of movement don’t load the hamstrings nearly as much as those that occur in a forward-backward manner (forward lunging for example). Exercises like this can therefore allow for early loading of the injured tissues without overstressing them and causing additional injury/more pain. (Check out this article for a full description of this exercise)
Rehab Phase 2 (Functional Stability & Return to Light Agility)
Usually about a week or two after the initial injury, we can start loading the healing tissue eccentrically. Before entering this phase it is recommend an athlete is able to walk and perform a high-knee marching movement without any pain.12 After a light dynamic warm up consisting of lateral shuffling or bike riding, single leg Romanian dead lifts or RDLs can be a good choice. I would start performing these without weight and then progressing to light weight as you can tolerate without any pain.
To perform the unweighted RDL (or windmills as some call them), start by standing on one foot. While keeping your free leg completely extended, pretend your hip is the center of a teeter-totter and rotate your body forward. You should feel some light tension rise in your stance leg hamstring as your bend over. If you can maintain balance, move until your chest is parallel to the ground before returning to the starting position. If you’re up for the challenge, hold this extended position for 5-10 seconds.
Once this becomes easy to perform and can be done for 15 reps pain free, you can start to add weight slowly to the movement. Hold a weight (kettle bell or dumbbell) in your hand opposite the stance leg. Perform the same movement as before.
Recommended sets/reps: 2-3 sets of 10-15 reps.
As we discussed before, the hamstrings are often strained during the “swing phase” of the running cycle (a time when they are placed under extremely high loads). For this reason, a high velocity exercise needs to be a part of late-stage rehab before returning to sports.11
An easy exercise for this is a high knees agility drill. Start by jogging in place slowly and progressively increase your velocity of your legs. You should get to the point where your feet are moving as fast as they would when sprinting.
Recommended sets/reps: 2-3 sets of 20 seconds.
Preventing Future Injury
Overall there is not a ton of research to help support any particular way to prevent future hamstring strains. However, the use of the Nordic hamstring exercise has shown promise in decreasing the rate of new and recurrent injuries in some athletes.13,14 This exercise is difficult to perform during the early stages of rehabilitation as it places a lot of force on the hamstrings but can be a part of the later-stages if it can be performed pain free.
Find a friend to help you with this exercise. Kneel with both knees together and have your friend pin your lower legs to the ground. Squeeze your glutes and smoothly lean forward. Try to lower yourself as slowly as possible to the ground. Once your hands and chest hit the ground, push yourself back quickly into the kneeling position you started in. The goal is to load the hamstrings as much as possible through a slow lowering process (challenge yourself to control your body for 5 seconds on the descent).
Recommended sets/reps: 2-3 sets of 5 reps.
Dealing with a hamstring strain can be difficult, especially if the injury is stubborn (as many are) and continues to return no matter how hard you try. I hope this article was able to give you a better understanding for why this injury occurs and a few ideas on how you can kick start treatment if you ever sustain a low-grade injury.
If however, you sustain a strain that is extremely painful, is associated with pain in your pelvis region and/or with nerve-like pain shooting down your leg, it is highly recommended to seek out a medical practitioner for help in the rehabilitation process.
Until next time,
- Prior M, Guerin M, & Grimmer K. An evidence-based approach to hamstring strain injury: a systemic review of the literature. Athletic Training. 2009 Mar-Apr. 1(2):154-164
- Arnason A, Sigurdsson SB, Gudmundsson A, Holme I, et al. Risk factors for injuries in football. Am J Sports Med. 2004;32(1 Suppl): 5S-16S
- Bennell K,Wajswelner H, Lew P, et al. Isokinetic strength testing does not predict hamstring injury in Australian Rules footballers. Br J Sports Med. 1998;32(4):309-314
- Gabbe BJ, Bennell KL, Finch DF, Wajswelner H, et al. Predictors of hamstring injury at the elite level of Australian football. Scand J Med Sci Sports. 2006:16(1):7-13
- Hagglund M, Walden M, Ekstrand J. Previous injury as a risk factor for injury in elite football: a prospective study over 2 consecutive seasons. Br J Sports Med. 2006;40(9):767-772
- Cressey E. “5 reasons you have tight hamstrings.” Web blog post. Ericcressey.com. 12 Jun 2012. Web. 28 Aug 2017.
- Gabbe BJ, Bennell KL, Finch CF. Why are older Australian football players at greater risk of hamstring injury? J Sci Med Sport. 2006;9(4):327-333
- Orchard J, Marsden J, Lord S, Garlick D. Preseason hamstring muscle weakness associated with hamstring muscle injury in Australian footballers. Am J Sports Med. 1997;25(1):81-85
- Yamamoto T. Relationship between hamstring strains and leg muscle strength. J Sports Med Phys Fitness. 1993;33(2):194-199
- Woods C, Hawkins RD, Maltby S, et al. The football association medical research programme: an audit of injuries in professional football – analysis of hamstring injuries. Br J Sports Med. 2004;38:36-41
- Verrall GM, Slavatinek JP, Barnes PG, et al. Clinical risk factors for hamstring muscle strain injury: a prospective study with correlation of injury by magnetic resonance imaging. Br J Sports Med. 2001;35:435-40
- Sherry MA, Beset TM. A comparison of 2 rehabilitation programs in the treatment of acute hamstring strains. J Orthop Sports Phys Ther. 2004;34(3):116-125
- Arnason A, Anderson TE, Holme L, et al. Prevention of hamstring strains in elite soccer: an intervention study. Scand J Med Sci Sports. 2007;18(1):40-8
- Petersen J, Thorborg K, Nielsen MB, et al. Preventive effect of eccentric training on acute hamstring injuries in men’s soccer: a cluster-randomized controlled trial. Am J Sports Med. 2011;39(11):2296-303