Hamstrings: The Behind-the-Scenes Heroes of Your Legs (and the Reason You Can't Touch Your Toes)

What is the Hamstring?

The hamstrings are a group of three muscles located at the back of your thigh. They start at the sit bone (ischial tuberosity) and extend to the back of the knee, either on the inside or the outside. These muscles play a key role in bending the knee and pushing the hip backward.

You might often see someone grab their hamstring when running fast or sprinting, as they feel a sudden pain in the back of their thigh.

Why Do the Hamstring Muscles Have Different Names?

Each of the three hamstring muscles has a unique name, reflecting their specific structure:

• Semitendinosus: This muscle is predominantly made up of tendon fibers.

• Semimembranosus: This muscle contains more membrane components.

• Biceps Femoris: This large muscle gets its name because it has two separate heads (like the bicep muscle in your upper arm).

  
  
  
  

How Are Hamstring Injuries Caused?

When you run, the hamstrings stretch out and lengthen, but they don’t simply stretch – they control this movement. During this phase, the muscle undergoes what’s called eccentric loading, where a significant load is placed on the muscle. While this is typically fine, it can become problematic if:

• You’re feeling sore,

• You suddenly increase your sprinting speed, or

• You run more frequently than usual.

  
  

In these cases, your hamstring might not be accustomed to the added stress, making it more vulnerable to injury. The muscle may become overstretched, leading to a tear. Overuse or poor flexibility can also contribute to a hamstring injury.

What Does It Mean If You Injure Your Hamstring?

If you suspect a hamstring injury, it’s important to differentiate it from other potential issues, such as groin (adductor) injuries or nerve pain (sciatic nerve) that may produce similar sensations.

To properly assess the injury, we’ll examine the muscle’s length, strength, and response to palpation (touching the muscle to check for tenderness). This helps us track your recovery over time and guide your return to running and sports activities.

Typically, depending on the severity, you’ll need 4-6 weeks of reduced or no running before you can gradually return to higher-intensity activities. Our team has extensive experience and a genuine passion for treating hamstring injuries, so if you're concerned, please don’t hesitate to come in and let us take a look!