Hamstring Anatomy

Your hamstrings are a team of four muscles that run down the back of your thigh. They include the biceps femoris (which has two parts: long head and short head), semitendinosus, and semimembranosus. Most of these muscles start at the bottom of your pelvis and stretch down past your knee, helping you bend your leg and extend your hip; key movements in sprinting, jumping, and cutting. One muscle, the biceps femoris short head, only crosses the knee, not the hip. The semitendinosus has a long tendon that wraps around the inside of your knee, while the semimembranosus helps stabilize the inner knee and even connects to structures like the meniscus and MCL. Each hamstring muscle plays a slightly different role, but together, they’re essential for explosive movement, balance, and injury prevention. Keeping them strong, flexible, and firing correctly is key if you want to stay fast and healthy on the field.

Hamstring injury prevention is all about building strength, control, and flexibility. The most effective exercises challenge the hamstrings both when they’re shortening (concentric) and lengthening (eccentric)—especially under load, since most injuries happen during high-speed lengthening. These moves not only strengthen the muscles but also improve coordination and resilience during sprinting, cutting, and deceleration.

Nordic hamstring curls – excellent eccentric strength builder

Romanian deadlifts (RDLs) – targets lengthened hamstring strength

Single-leg glute bridges – isolates and activates hamstrings in a hip-dominant movement

Hamstring sliders or Swiss ball curls – works both concentric and eccentric phases

Good mornings – strengthens the posterior chain with hip hinge focus

Banded or cable hip extensions – builds control through full hip range

Eccentric leg curls (machine) – slows down the lowering phase to mimic late swing phase stress

The hamstrings are not only powerful movers, but stabilizers as well, especially in high-speed sports. Their most intense work occurs during the final 25% of the swing phase of gait, when they contract eccentrically to decelerate the swinging leg. During this phase, they reach their maximum length and tension, making it the most common moment for strain injuries. Functionally, the hamstrings play a dual role: they extend the hip, flex the knee, and assist in rotating the lower leg, depending on the muscle and joint position. Their stabilizing capacity is especially important at the knee; working synergistically with the ACL, the hamstrings resist anterior tibial translation during the heel strike phase of gait. If an athlete is playing through a hamstring strain, they are more vulnerable to ACL injuries due to compromised dynamic control. Of note, the semimembranosus plays a critical role in posteromedial knee stability, actively protecting the medial meniscus and MCL, especially during cutting, pivoting, and flexion. This dynamic interaction between movement and stability highlights the importance of healthy, well-conditioned hamstrings for injury prevention and high-level performance.