Causes of Hamstring Strain
Generally from excessive tensile forces on the hamstring, some of the most common issues with hamstring strain are overuse, tight hip flexors, and/or weakened glutes, hamstring, and core. We will examine causes related to each of these below.
A. Volume or Intensity Increase
Tissue takes time to adapt and get stronger, so if you persistently push it beyond its limits of recovery then you will get hamstring discomfort or injury. This not only occurs from increasing intensity too quickly in training, but also from doing too much too soon after having taken time off, such as for travel, injury, or sickness, during which the tissue has weakened from inactivity.
QUESTIONS:
- Did I recently change my running program?
- Do I allow adequate rest in my running program?
- Do I participate in other activities that may be stressing the hamstring?
This “U” shape graph indicates Injury Risk (Vertical/ Y-Axis) and Load (Horizontal/ X-Axis). If you don’t train much (low load), your risk of injury is high due to the low resilience of the tissue. If you are training a lot, your risk for injury is also high due to potential overload. The middle zone provides the lowest risk of injury. To increase load capacity, you will have to move toward the higher load zone, but the key is to do so progressively to allow the tissue to adapt. This will be addressed further in the conditioning and training portions of ARC Running.
B. Glutes & Hips
During the swing phase of one’s gait, the hamstring muscles help decelerate the leg from going too far forward. Some muscles that help support that effort are the gluteal muscles, so if the glutes are weakened there tends to be more strain on the hamstrings to compensate.
ASSESSMENT TESTS:
Side Planks
If you can hold for 90 seconds, you are good. Less than 90 seconds indicates weakness in the side of the hip, as does trunk rotation or dipping hips that break your initial position.
Instructions: Elbows aligned with shoulders, come up on your side. Keep your body straight throughout the duration of the test. The test is complete when your hips begin to drop, you begin to rotate, or you get too tired to continue.
Single Leg Glute Bridge
If you can hold for 60 seconds, you are good. Less than 60 seconds indicates weakness in the glutes, as does an inability to maintain a level body/ hip height and/or experiencing trunk rotation while trying to maintain the position.
Instructions: On your back, bring your hips up with arms across your chest. Hold your body level throughout the duration of the test. The test is complete when your hips begin to drop, you begin to rotate, or you get too tired to continue.
Single Leg Squats
Can you squat without the knee wobbling or caving inward? Excessive knee movement or inability to reach a 90-degree squat indicates hip/leg weakness or motor control deficits.
Instructions: On one leg, begin to squat down by bringing your hips back and then bending your knee. Look to see if the knee is aligned with the middle of your foot throughout the duration of the movement.
C. Hamstring Eccentric Strength
Weakness in the hamstring muscles limits tissue resilience, particularly related to eccentric load, which is vital to the strength and function of the hamstring. Eccentric loading refers to the tension of the muscle as it lengthens. Hence, most injuries occur when the hamstring is in a stretched and loaded position.
ASSESSMENT TEST:
Hamstring (Single Leg Bias)
Though the traditional tests bias the glutes, if you bring your leg out farther you will bias more of the hamstring. Though not a perfect test, it can provide a sense of hamstring strength and endurance.
Instructions: If you are experiencing high to moderate pain, refrain from this test until your symptoms subside. Otherwise, you should be able to maintain 60 seconds with the knee in a 45 degree angle with your hips up.
D. Hip Flexor Length
The hip flexor are a group of muscles located on the front of the hip: the iliacus, psoas major (also called the iliopsoas), and the rectus femoris. They essentially perform the opposite action of the hamstring by helping bring your hip forward when contracted, while the hamstrings bring your hip back when contracted. If the hip flexors are restricted, it may pull the pelvis anteriorly, increasing the strain on the hamstring muscles. Furthermore, tightness in the hip flexor muscles can cause reciprocal inhibition, where the muscle on the opposite side (in this case, the hamstring) becomes weaker due to inhibition. The hip flexors tend to be tight as a result of us sitting for prolonged periods of time, and as such the hip flexors adaptively shorten. Thus, it is important to stretch the hip flexors to decrease the strain on the hamstring.
ASSESSMENT TEST:
Kneeling Test
The goal is to be able to get your hip 15-20 degrees into hip extension relative to your body.
Instructions: First put your pelvis in a posterior pelvic tilt (i.e. front rises, back drops – demonstrated at start of video) while in a kneeling position. Once done, lean forward with your body straight. You should feel a stretch on the front of your hip and thigh. If you feel a significant stretch, then complete this stretch regularly. If you are able to get the hip back without much stretch, then you are good to go.
E. Other Risk Factors
- Prior Injury: Not having fully recovered and/or strengthened weakened area(s).
- Training Dynamics: Different running surfaces, speeds, and distances.
- Sleep, Nutrition, and General Recovery: If you don’t eat well, your tissues don’t have the fuel needed to restore muscle.
Still Need Help?
You are welcome to meet virtually with our PT for additional feedback and assessment. Otherwise, continue to the next step to learn how best to manage the pain from your injury.