Hamstring injuries refer to damage or strain to the muscle or tendon. A hamstring injury can commonly be classified as one of the following:

Hamstring Strain

This is the most common type of hamstring injury, occurring as a result of overstretching the muscle fibers and/or tendon. A hamstring strain involves stretching of the hamstring muscle or tendon without tearing.

Hamstring Tear

This occurs when a portion of the hamstring muscle fibers or tendon tears/ruptures. If only a portion of the hamstring muscle fibers or tendon tears, this is considered a partial hamstring tear. If a complete tear or rupture occurs, then the full thickness of the muscle fiber or tendon has torn and is referred to as a full tear.

Hamstring Avulsion

This is the most severe type of hamstring injury. It occurs when the hamstring tendon fully separates or pulls off from the pelvis bone where the hamstring inserts (ischial tuberosity).

Avulsion Fracture

This occurs on rare occasions when instead of the tendon pulling off the bone, the hamstring tendon pulls off a piece of bone with it. Avulsion injuries can occur from a burst of speed seen in ice skating, weightlifting, and skiing.

• Muscle Imbalance: One of the leading causes of hamstring injuries is muscle imbalance. When the quadriceps are significantly stronger than the hamstrings it can lead to an increased risk of hamstring injury.
• Inadequate Warm-Up: Failing to properly warm up before engaging in physical activities can make the hamstrings more susceptible to injury. Warming up helps to increase blood flow, muscle temperature, and flexibility.
• Sudden or Explosive Movements: Activities and sports that involve sudden and explosive movements, such as sprinting, running, lunging, jumping, kicking, or rapid changes in direction, put the hamstrings under considerable stress and can lead to injury. Falling may also result in hamstring injury from a sudden movement, particularly if the fall results in doing the splits.
• Fatigue: When the muscles are tired, they are more prone to injury. Overexertion and muscle fatigue can increase the risk of hamstring injuries. Excessive training, or overtraining, without adequate rest can lead to overuse injuries.
• Lack of Flexibility: Inflexible hamstrings are more vulnerable to strains. Insufficient stretching can result in reduced flexibility and make the muscles more prone to injury.
• Previous Injuries: If you’ve had a previous hamstring injury, you may be more susceptible to re-injury due to residual weakness or scar tissue. Failing to rehabilitate and strengthen the hamstring muscles properly after an initial injury can leave them weakened and at risk for further damage.
• Poor Running or Biomechanics: Running with improper form or biomechanics can overload the hamstrings, increasing the risk of injury.
• Age: As people age, their muscles may lose some flexibility and elasticity, making the hamstrings more susceptible to injury.
• Environmental Factors: Running on uneven surfaces or in extreme weather conditions can increase the risk of injury.

The symptoms may vary in severity depending on the extent of the injury. Common symptoms of a hamstring injury include:

• A sharp pain in the middle or upper back of the thigh near the buttocks. The intensity of the pain can range from mild to severe.
• Difficulty putting weight on the injured leg, resulting in a limp.
• Pain with sitting
• Swelling
• Bruising and discoloration
• Hamstring weakness
• Muscle spasms or cramps
• Difficulty fully extending or straightening the leg.
• Audible “pop” or snapping sound at the time of injury, especially in severe hamstring injuries.

Physical Exam

After obtaining a complete medical history, including description of your symptoms and previous injuries, a thorough physical exam will be performed. The examination includes range of motion and strength assessment, as well as checking for bruising, tenderness, and swelling. If the tendon has pulled away from the bone, the muscle may appear balled up at the back of the thigh.

Imaging

X-rays may appear normal with most hamstring injuries; however, if an avulsion fracture has occurred and the hamstring tendon has pulled a piece of bone away with it, this will be visualized on x-ray. An MRI of the hip provides detailed images of the hamstring tendon, including the location of the injury, the extent of the injury, and the degree of tendon retraction.