The term “hammies” is an informal name for the hamstring muscle group, located in the posterior thigh. These powerful muscles are fundamental to almost every lower-body movement, from standing to sprinting. Understanding their structure and function is key to appreciating their importance for daily mobility and athletic performance. Due to the high demands placed upon them during physical activity, they are also one of the most frequently injured muscle groups.
Anatomy and Where They Are Located
The hamstrings are not a single muscle but a group of three distinct muscles running along the back of the thigh: the biceps femoris, the semitendinosus, and the semimembranosus. They are situated in the posterior compartment of the thigh, lying between the hip and knee joints.
These muscles collectively originate primarily from the ischial tuberosity, commonly known as the “sit bones,” a bony prominence on the bottom of the pelvis. From this shared starting point, the muscles extend down the thigh toward the knee. They insert, or attach, onto the bones of the lower leg: the tibia and the fibula.
The biceps femoris is the most lateral (outer) of the three, attaching to the head of the fibula. The semitendinosus and the semimembranosus are located more medially (inward) and attach to the inner side of the tibia. This arrangement means they cross both the hip and knee joints, classifying them as biarticular muscles.
Essential Roles in Movement
The dual-joint crossing of the hamstrings gives them two main actions, critical for locomotion and body stability. Their primary function is hip extension, which involves moving the thigh backward. This action is necessary for powerful movements like pushing off the ground while running or jumping, and for standing up from a seated position.
The second major role is knee flexion, the act of bending the knee. This movement is utilized every time a person walks or runs, as the foot is lifted and the leg swings forward. The hamstrings are also active in decelerating the lower leg during the swing phase of running, working as an antagonist to the quadriceps muscles to control movement before the foot strikes the ground.
The muscles also contribute to the rotation of the lower leg, particularly when the knee is bent. The semitendinosus and semimembranosus help with internal (medial) rotation, while the biceps femoris assists with external (lateral) rotation. This combination allows for the complex, coordinated actions required during daily activities and sports.
Preventing Common Hamstring Injuries
The most common issue affecting this muscle group is a hamstring strain, often called a “pulled hamstring,” which is a tear in the muscle fibers. These injuries frequently occur during high-speed activities like sprinting, especially during the final swing phase when the muscle is forcefully lengthening while contracting. Prior injury and muscle fatigue are significant risk factors.
A primary way to reduce injury risk is to incorporate a dynamic warm-up before activity, which raises muscle temperature and prepares the tissues for work. This involves movement-based exercises, such as leg swings or light jogging, rather than static stretching. Consistent eccentric strengthening exercises are also highly effective, as they train the hamstrings to resist lengthening forces under load.
The Nordic hamstring exercise is a specific eccentric movement shown to reduce injury rates in athletes. General hip extension exercises that target the muscle group’s primary function should also be included. A cool-down period with light stretching after exercise can help maintain flexibility and aid in recovery.
In the event of an acute strain, the R.I.C.E. protocol is the initial recommended treatment for the first 48 to 72 hours. This protocol stands for:
- Rest, which involves avoiding activities that cause pain.
- Ice, applied for short intervals (typically around 10 minutes) to provide pain relief and control bleeding.
- Compression, using a bandage to help manage swelling.
- Elevation, raising the injured area above heart level to manage swelling.