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Knee Pain: Can Tight Hamstrings Cause Knee Pain?

By Last updated on March 23rd, 2022March 23rd, 2022No Comments

Knee pain results from a complex series of biomechanical interactions. The hamstrings muscle group, located in the back of the leg, helps support the knee. This supporting role makes these muscles a key factor in knee-injury protection and knee-pain prevention. Malfunctioning hamstrings create faulty movement patterns, which affect the alignment and health of the knees.

Anatomy of the Hamstring

The “Hamstring” is actually a group of three muscles on the back of the leg. The hamstrings anchor via tendons to the butt bone at what is called the ischial tuberosity. They stretch the full length of the upper leg and insert just below the knee.

These hamstring muscles work together to collectively perform hip extension and knee flexion (bending the knee) including:

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

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What causes Hamstring tightness?

Tight Hamstrings

The hamstring muscle plays an integral role in most leg movements. They are an important muscle group because they balance the actions of the quadricep muscles, keeping the pelvis and spine neutral when moving the hips and legs. The three most common causes of hamstring tightness include:

  • 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 the 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”.
  • Nerve Entrapment: The bicep femoris muscle runs over top of the sciatic nerve, and sometimes the sciatic nerve can get trapped under it.
  • Lumbar Disc Herniation: Like with nerve entrapment, a disc herniation can causes hamstring tightness. If a patient has a disc herniation, the hamstrings and other muscles around the lower back will go into overdrive. They do this to protect the area of the spine that is injured. This is called “protective tension”.

How do Tight Hamstrings relate to Knee pain?

The hamstrings are biarticular, they will affect the health of the knee, hip and even back.  Most athletes who are tight in their hamstrings can suffer a host of problems.

For example, when squatting with a heavy weight, they will not be able to lower their hips past 90 degrees.  This keeps them working in a ‘safe’ mid range zone, but exasperates the issue as the hamstring will not be fully lengthened. Then when it comes time to explode out of the squat, the full length of the hamstring muscles are not utilized.  This can get into a vicious circle, ending in weak and tight hamstrings.

If the hamstrings are too tight and do not allow full hip extension, the quadriceps will take over from the inefficient hamstrings, putting a tremendous load and strain on the knee. All four quadriceps converge to form a single tendon above the knee that attaches to the top and sides of the patella, before attaching via the patellar ligament to the tibial tuberosity. Therefore, if the quadriceps group works needlessly overtime, it’s going to affect the knee.

How to treat Tight Hamstrings?

The simple answer to eliminate hamstring tightness is to loosen them through exercises including stretching. There are many helpful stretches for the lower body to prevent tightness that attributes to knee pain. Some more specific and effective stretches include:

Lunging Hip Flexor Stretch:

  • Kneel on one knee. Place the opposite foot flat in front, with the front thigh parallel to the floor.
  • Lean forward, stretching the hip toward the floor.
  • Tighten the butt; to allow a deeper stretch.
  • Reach up with the arm on the same side as the knee on the floor. This will help deepen the stretch.
  • Switch sides and repeat.

Figure Four Stretch:

  • Lie on the back.
  • Cross the left foot over the right quad, and bend the right knee.
  • Hold the back of the right leg and gently pull it toward the chest.
  • Switch sides and repeat.

Standing Hamstring Stretch:

  • Stand on the right foot with the left foot in front, heel on the floor, toes up.
  • Hinge forward at the hips and bend the right knee sitting back a bit.
  • Bend the right leg, keep the left leg completely straight with the weight on the edge of the heel.
  • This stretches the hamstring of the straightened leg.
  • Switch sides and repeat.

Side Lunge:

  • Lunge out to one side, bending the knee and keeping the opposite leg straight.
  • Try to keep the foot of the straight leg on the floor.
  • Place fingertips on the floor in front to balance.
  • This stretches the hips and inner thighs.
  • Switch sides and repeat.

Calf Stretch:

  • Stand in front of a wall with one leg straight behind and the other in front, slightly bent.
  • Place hands on the wall and push against it.
  • Keep your back leg straight, heel planted on the floor.
  • Switch sides and repeat.

Quad Stretch:

  • Lie on one side.
  • Keep the bottom leg straight and bend the top knee towards the butt.
  • Hold the top foot with a hand, pulling it toward the butt.
  • Keep the hips stable.
  • Switch sides and repeat.

Stretching is effective, but there are also dangers of hyper-flexibility. Joint integrity should never be compromised in favor of excessive flexibility. Overstretching the hamstrings may affect joint stability, leaving the knees vulnerable to pain.

Alternative Treatments

Stretching can be a cure for most situations involving knee pain. However, in extreme cases it may not be enough. Surgery is an option but is rather invasive and expensive. Regenerative cell therapy allows patients to use regenerative cells and growth factors to help repair and regenerate damaged cells and tissues in their knee.

Stem Cell Therapy is the most advanced and, arguably, most effective regenerative therapy. Stem cells can heal and restore damaged joints and have the ability to regenerate cells. Stem cells can be used to stimulate a regenerative healing process in the knee and in this way can be used to provide many patients powerful, long-lasting relief.

Platelet Rich Plasma (PRP) therapy contains a concentration of many different growth factors that reduce inflammation and promote the body’s healing capabilities. Instead of a long path to recovery with a risk of complications, PRP therapy allows for treatment of the knee with local injections. PRP presents patients with a long-lasting treatment option by using the body’s natural healing process. PRP research has shown that it can decrease pain and increase functioning in patients suffering from knee pain.


There are a few things that can stop tightness before it starts. Recommended activities include:

  • Warm up before engaging in different sports or other intense activities. At least 10 minutes of walking, light jogging, or easy calisthenics may help prevent hamstring tightness.
  • Regular hamstring stretches before and after activities may also help prevent tightness. Try to take three to five minutes before and after sports or activities to stretch.
  • An overall strong and fit body.
  • Eat a healthy diet, and drink plenty of water to fuel and replenish muscles.


Knee pain is a common ailment suffered by many people. It can stem from many things including issues with one’s hamstrings. This is in part due to the hamstrings’ propensity to help support the knee.

The hamstring muscle plays an integral role in most leg movements and therefore can lead to some problems. In many cases these knee issues can come about from being inflexible in the hamstrings and adding too much pressure to the knees.

An easy treatment usually includes a balanced exercise of stretching and various strength building of the legs and back.

Dr. Matthew HC Otten

Director of Regenerative Orthopedic and Sports Medicine
Fellowship-trained & Board Certified in Sports medicine
Director Angiography at Harvard Clinical Research Institute
Michigan State University Alumni


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