Have you ever witness an athlete collapse grabbing their leg and vigorously signaling for help? More than likely, the athlete has injured their hamstring. As you are watching, you may not know that what you seen had many signs prior to the injury from increase training load, decreased hip range of motion, and missed practices because of hamstring tightness (O’Reilly 2015).
The hamstring is a muscle behind your leg that includes the Biceps femoris, semitendinosus and the semimembranosus muscles, which is show in figure 1 below. The job of the hamstring is to extend the leg straight back and bend the knee. In a hamstring injury, the tendons of the hamstring either stretch to far, slightly tear, or completely come off of the bone. Fields and colleagues discovered that hamstring injuries account for 28% of injuries in athletics with a 33% chance of re-injury (2016). Therefore, there should be precautions to avoid the injury as well as healing the injury. This blog will explain how an injury can occur, physical examinations, how severe an injury is, and what rehabilitation methods will it take to strengthen the muscle again.
Injury to the hamstring can be very painful, as seen in figure 1 above. Hamstring injuries usually occur during eccentric contractions, which involve the lengthening of a contracting muscle (Eveleigh 2013). The hamstrings contract eccentrically during the deceleration stage of running. Then the hamstrings extend the hip and this is the point the hamstring is most prone to injury because of the quick change needed, but the muscle is mistiming the rapid contractions (Eveleigh 2013).
Hamstring injuries risk factors range from modifiable risk factors and non-modifiable risk factors. Modifiable risk factors range from: increased volume of training, fatigue muscles, muscle imbalance, poor biomechanics, and cross-pelvic posture (Fields et.al. 2015).
Modifiable factors are factors that you can take measures to do something about them.
When the muscles surrounding the hamstring as well as the hamstring are fatigue, it reduces the capability for the hamstring to obtain energy, making them more prone to injury (North Carolina Orthopaedic et.al. 2015).
Each muscle in the body has its own job but also supports movements of other muscles. When a muscle group is weaker than the opposing group, it can lead to a strain. The hamstring’s opposing muscle is the quadriceps. In figure 2 below, it shows the hamstring and quadriceps as they would work in motion. Generally, in a hamstring injury, the quadriceps are stronger than the hamtrings, causing the hamstring to fatigue faster than the quadriceps, leading to an injury (North Carolina Orthopaedic et.al. 2015).
Muscles in the body are called a kinetic chain, which is all muscles in the body act as a series of interdependent structure to coordinate and control movement (Fields et.al. 2015). If any part of the body is not balanced and disturbs the kinetic chain, it can cause a hamstring injury. For example, cross pelvic posture is an example of the kinetic chain being disrupted, as a result of the abdominals and hip extensors being tight, the hip flexors are tight, and the lumbar extensors are tight; this disturbance can cause a hamstring injury (Fields et.al. 2015).
Non-modifiable Risk Factors
Non-modifiable risk factors are factors that you can not change.
Prior Hamstring Injury
When an athlete has injured their hamstring, the scar tissue that builds up do not possess the elastic properties that connective tissue of a healthy muscle has, which makes the athlete more prone to strain (Eveleigh 2013). Also, when an athlete does not fully rehabilitate their leg, is can cause another injury due to the fact the leg is not fully healed (Eveleigh 2013).
The older an athlete is, the rate of injury increases due to the fact that the older you get the weaker muscles get.
Once an athlete figures they have a hamstring injury, they can get examined from a doctor to determine they severity and to give an estimation on how long rehab may take. During an examination, doctors will ask questions about prior injuries and your medical history which can give a clue to the type of injury. Doctors will give a physical examination touching the leg across the muscle to have an idea of where the injury is and how sever it is (Wedro 2015). Physical therapist has created a grading scale to determine the severity of an injury. In figure 1 below, it shows an outline of what the hamstring muscles would look like depending on the grade of the injury.
A grade 3 injury is the most severe on the hamstring injury scale. This injury is easy to diagnosed because you would have heard a popping noise in your leg, felt a crack in your leg, and you will drop to the ground because of the pain. By the next hour or two, your leg will begin to bruise because of the torn muscle leaks blood to the injured area. Generally, this injury may take surgery to heal and rehab that can take up to 6 months to a year to fully heal. If there is any question to a fracture, doctors will use a MRI to evaluate the extent of the muscle injury and give more detail on recovery time (Wedro 2015).
A grade 2 hamstring injury is considered to be a partial tear in the muscle. As you are running or dancing, you may pull up and as you’re walking, you being to limp and it will be painful. There may be some heat feeling in the muscle but there is a less likely chance of having a bruise. This can take 6 weeks to 6 months out and into rehabilitation.
A grade 1 hamstring injury is the trickiest injury to discover. You don’t see any bruises, don’t see any swelling, and can’t feel any heat. It just feels like a tightly sore muscle. They are commonly diagnosed as a strain, and can take around 3weeks to 3 months to heal, depending on how early it was diagnosed.
Regardless of the grade level of the injury, physical therapist always recommends the RICE treatment first in the beginning stages of healing. The RICE treatment means to rest, ice, compress, and elevate (North Carolina Orthopaedic et.al. 2015).
Rest: Take off of the activity that caused the strain.
Ice: Ice for 20 minutes around three times a day, but do not apply ice right on skin.
Compress: Wear an elastic band in order to reduce blood loss and swelling in the leg.
Elevate: Have your leg elevated in order to reduce swelling and blood less in your leg
In the past, physical therapist would use concentric exercises during treatment rather than eccentric. Concentric exercises are those that contract the hamstring when your foot moves closer to your hip, or shortened (Harris 2016). Eccentric exercises are those that contract when the hamstring lengthens (Nichols 2010). Because the hamstring is not used to shorten the length of a stride, Kaminski and colleagues evaluated the difference between eccentric versus concentric exercises and the healing process of a hamstring injury (Kaminski et.al. 1998).
In setting up this experiment, twenty-seven male students volunteered to participate (Kiminstanki et.al 1998). To determine who would be eligible for the study, a health questionnaire had to be filled out before participation. Before the research was conducted, the 27 men were placed in either a control group, a concentric training group, or an eccentric training group. These subjects ranged from 18-25 years of age, from 5’7”- 6’0” feet tall, and from 123 lbs. to 205 lbs. in weight.
The subjects in this design were tested in a biomechanics laboratory, while the rehab was carried out in a physical therapy clinic. The subjects in the control group refrained from weight training for 6 weeks. The subjects in the eccentric and concentric groups trained for 2 days a week for 6 weeks.
Kaminski and colleagues found that the concentric group improved 19%, while the eccentric group improved 29%. Also, the eccentric group was the only group that had improvement in body weight ratios and isokinetic peak torque- which is increased flexion of the knee.
After it was established that eccentric exercises help more than concentric exercises, physical therapist use eccentric exercise in rehabilitation treatments. Not only did this study show eccentric exercises increased healing in the hamstring, but also in the the strengthening of the knee.
Eccentric Rehabilitation Exercises
In the kinetic chain of muscles, the hamstring and the glutes help in hip extension. If the glutes are not strong enough, it will make the hamstrings work even harder. The eccentric strengthening and stability exercises for the hamstring and glutes include: bridges, Nordic hamstring curls, monster walks, and lunges.
The hamstring bridge to strengthen your hamstring and glutes. In this exercise, you lie on your back with your knees bent and your feet both flat on the floor hip width apart. Then, place your arms beside your torso with your palms facing downwards, press through your heels and lift off of the ground and contract your hamstrings and squeeze your glutes. Figure 1 above is a visual view of how to do a hamstring bridge.
Figure 2: An image from Will Levy of a visual on how to do Nordic hamstring curls.
Nordic Hamstring Curls
Another exercise that can help strengthen the leg muscles and glutes is the Nordic hamstring curls. In this exercise, you kneel to the ground and secure your feet and lower your torso to the ground slowly until your hamstring feels like they are about to pop and catch yourself in a push-up position and push yourself back up (Hitchko 2015). Figure 2 above is a visual of how to do the Nordic hamstring curls. This exercise can help you absorb force when you decelerate instead of losing force.
Single Leg Dead Lift
Exercises to help get the glutes up to par include single straight leg dead lift in order to address the extensor function (Boyle 2011). To do this exercise, you stand up straight with your palms facing your thighs and then lift one leg off of the ground while having a slight bend in the other leg. While lifting the leg, you will lean forward at your hips and come back up when your leg is parallel to the ground.Figure 3 above shows how to do the single dead lift exercise.
When doing monster walks, it is preferred to use a band that has moderate resistance. First, place the band at the feet with your knees slightly bent and chest upright. Then you will walk forward in a heel to toe motion then switch and go backwards going toe to heel. Figure 4 above shows how to carry out the monster walk exercise.
Lunges help with your form, stride length, and flexibility for when you are sprinting. To do this exercise, you start with one leg forward and bend the knee. When you are doing this make sure the front foot stays flat and the knees do not move over the front toes when you move down. Figure 5 above shows how to lunges as well as how not to do lunges.
In worst case scenarios, if the hamstring is completely pulled from the bone, which is called a tendon avulsion, surgery may be needed to treat the hamstring prior to the eccentric exercises (North Carolina Orthopedic et.al. 2015).
In order to repair a tendon avulsion, the surgeon pulls back the hamstring and removes and scar tissue. Then the hamstring tendon is reattached to the bone using staples or stitches.
After surgery, in order to protect the repair of the leg, you may need crutches or a brace to keep weight off of your leg. It will take about 3 months to 6 months of rehab before returning to your activity.