3 Causes of Hamstring Tightness

Before we can dive into what may cause hamstring tightness, it is important to understand exactly what the hamstring muscle group does for the body.

3 Causes of Hamstring Tightness


The “Hamstring” is actually a group of three muscles on the back of the leg.

These hamstring muscles work together to collectively perform hip extension (lifting your leg backwards) and knee flexion (bending your knee) include:url

  1. Bicep Femoris: this muscle has two origination points (Hence “Bicep”). The long head of the muscle originates on the pelvis, which means its involved in both hip extension and knee flexion. It becomes a weaker knee flexor when the hip is extended, and vise versa. The short head, is primarily involved with knee flexion. The bicep femoris lies over the sciatic nerve, which is important to remember.
  2. Semitendinosis: this muscle helps with hip extension and knee flexion. It is also responsible for medial rotation of tibia on femur when the knee is flexed, and medial rotation of the femur on tibia when the hip is extended.
  3. Semimembranosus: the semimembranosus performs the exact same function as the semitendinosus. These muscles also both help to counter forward bending at the hip.


The hamstring muscle plays in integral role in most leg movements. They are an important muscle group because they balance the actions of the quadricep muscles, keeping your pelvis and spine neutral when moving your hips and legs. There are many things that may cause hamstring tightness but this post will focus on these three causes of the hamstring tightness:

1. anterior pelvic tilt
2. nerve entrapment
3. lumbar disc herniation


3 Causes of Hamstring Tightness

Anterior pelvic tilt means that the top of the pelvic bone is tilted to face the front (anterior) of the body. The quadriceps attach to the front side of the pelvic bone (pulling the pelvis into an anterior tilt), while your hamstrings attach to the back side (posterior) of the pelvic bone (pulling it into posterior tilt). Therefore, when an individual has an anterior pelvic tilt (which is common in women) it forces the hamstrings to work extra hard to counter the forces causing the anterior tilt. Because the hamstrings are on overdrive, they are basically always “ON” and therefore always contracted or “tight”.

When someone has anterior pelvic tilt causing the hamstring “tightness”, over stretching the hamstrings will actually just make the problem worse. It will keep the hamstrings from being able to fight against the forward pull on the pelvis. The best way to combat this kind of hamstring tightness, is by re-establishing neutral spine using some of the exercises we posted last week–check it out!


3 Causes of Hamstring Tightness

Just because you feel symptoms in your hamstring, does not mean it actually coming from your hamstring. One of the major causes of hamstring symptoms stems from nerve entrapment. The bicep femoris muscle runs overtop of the sciatic nerve, and sometimes the sciatic nerve can get trapped under it. 

Some signs that it may be coming from the nerve and not your muscle tissue:

  • any feelings of numbness, tingling, or burning in your leg
  • when you reach for your toes, you feel pulling behind the knee or in your calves

These are both signs that the nerve is getting stuck somewhere along the leg preventing it from functioning as normal. If you have signs like this, you should see a physical therapist to help get the relief your nerve so desperately needs!


3 Causes of Hamstring Tightness

Like with nerve entrapment, a disc herniation can causes hamstring tightness. If you have a disc herniation, your hamstrings and other muscles around your lower back will go into overdrive. They do this to protect the area of your spine that is injured. This is called “protective tension”.

Signs you may be struggling with a disc herniation problem are:

  • pain after prolonged sitting
  • pain when getting out of bed in the morning
  • sharp pains in lower back that continue down your leg
  • weakness in muscles of your leg

If you experience these problems, you should see a doctor or physical therapist to get it identified and alleviated. There are many tests that can be performed to tell if hamstring tightness is stemming from your back and not your muscles!

Don’t be alarmed though, hamstring tightness can be just exactly that- hamstring tightness. And it can even be caused by spending a HUGE portion of your day in a seated position. If that sounds like you,  try this L-sit stretch at home:

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Hold this stretch for 3 minutes on each leg. Keep both of your knees straight. Keep your back flat (NOT arched). With the leg on the wall, point your toes toward your body for an added stretch!

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