Hamstring muscles – Functions & Structure

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Hamstring muscles are skeletal muscles behind the thighs. We use them for activities like walking, climbing, sports or performing any other regular moments. A sportsperson or an athlete is not new to a hamstring injury.

What are hamstrings?

The hamstring muscles are skeletal muscles. A person has voluntary control over how they work and move. Every individual will have three hamstring muscles at the back of the thigh that they will use to perform various activities and leg moments.

Hamstring muscles are prone to injury, especially in athletes who run or sprint often. Quick halting, slowing down, or changing direction can strain these muscles tremendously. Extending the leg during running can also overstrain the muscle, causing hamstring injury.

A hamstring injury is also called a pulled hamstring.

Healthy hamstring muscles serve a variety of functions like

  • Moving the knee joint
  • Extends the hip joint and
  • Rotating the hip flexors and hip joint.

These muscles located at the back of the thigh, start at the hip, and are inserted into the knee.

hamstring muscles

Structure of the hamstrings

The three muscles making up the hamstring are:

Biceps femoris

The biceps femoris is the closest muscle to the outside of the body and serves a significant function of flexing the knee. Hip extension and rotation of the lower leg from side to side is possible with the help of this muscle.


This muscle is located in the middle of the body and flexes in the knee joints and hip, offering medial rotation for the hips and the lower leg.


The semitendinous muscle is between the above two muscles, and the primary function of this hamstring mimics that of the semimembranosus.

All these hamstring muscles are made up of numerous tiny elastic muscle fibres helping the muscles contract and tighten. The muscle fibres are white and red. These hamstring muscles look striped under the skin.

Hamstring muscle strain

Hamstring muscle strain results from overstretched muscle fibres causing the body to exhibit strains that can range from mild to severe.

  • The muscle fibres can overstretch and not tear, causing a person to feel mild hamstring muscle pain or swelling.
  • In severe cases, one or more hamstring muscles are partially torn, causing excessive pain and preventing a person from using their leg.
  • In worst cases, the muscle tissue can be completely torn from the tendon and can pull some bones away with it. The swelling and pain are intense and cause extreme difficulty.

Such injuries are common for athletes. Athletes running at a fast speed have higher chances of injuring their hamstring.

Some of the other risks of hamstring muscle injury include

  • Age above 40
  • Young athletes
  • History of previous hamstring injuries
  • Muscle fatigue
  • Tight hamstring
  • Not warming up or stretching before activity

What can cause hamstring muscle injury?

Hamstring injury is common and can occur to anyone. Athletes need to be extra cautious with their hamstrings. Exercising with tight muscles works coordination muscle imbalances and fatigue can cause injury to the hamstring.

Symptoms of hamstring injuries

A hamstring injury can cause

  • Big lump behind the thighs
  • Bruising
  • Dislocation
  • Burning sensation
  • Difficulty bearing weight
  • Lack of knee mobility
  • Sharp pain behind the thighs
  • Hamstring muscle weakness and
  • Swelling

Reducing the chances of a hamstring injury

A person can minimise the chances of injury by taking care of the hamstring muscles by

  • Resting the hamstring muscle between workout
  • Stretching and warming up the hamstring muscles properly
  • Seated hamstring stretches and lying down hamstring stretch can mobilise the hamstring muscles.
  • Medication and pain relief
  • Adequate rest and recovery to ensure the injury doesn’t progress.
  • Ice bath

To sum up

If a person is active in sports, they might experience pain or disturbance in the hamstring. With proper strengthening exercises, a person can avoid the complication of the injury.

Hamstring muscle injuries are common and requires long recovery time. Stretches can help prevent injuries and mobilise the muscles.


Why are hamstring muscles called so?

The Ham in the hamstring comes from an old word meaning crooked. This refers to the crooked part of the leg- knee.

How long does the pull hamstring heal?

A mild or moderate strain of the hamstring can heal within 3 to 7 weeks with diligent home therapy. However, medical supervision is advised.

Why does the hamstring hurt?

The hamstring can generally hurt due to muscle overload when a person is running or the leg is fully stretched out.

Is walking good for a pulled hamstring?

Gradually increasing the physical activity level, like walking, can heal the hamstring and make it stronger. Including some strengthening exercises and stretching and not pushing oneself too hard can help with recovery.


The Information including but not limited to text, graphics, images and other material contained on this blog are intended for education and awareness only. No material on this blog is intended to be a substitute for professional medical help including diagnosis or treatment. It is always advisable to consult medical professional before relying on the content. Neither the Author nor Star Health and Allied Insurance Co. Ltd accepts any responsibility for any potential risk to any visitor/reader.

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