Your hamstrings are a group of three cable-like muscles at the back of your thigh running from your hip to your knee. They’re largely responsible for flexion of the knee joint and extension of the hip joint, along with some rotation of your lower leg and glute stability.
The semitendinosus and semimembranosus (what a mouthful) flex/bend your knee and work with your glutes to extend your hip, like at the top of a hip thrust
The biceps femoris has two heads, long and short, that help flex your knee and externally rotate your lower leg. They also support your hip when you walk, run, or jump.
These three muscles are crucial antagonists for your quads and are commonly injured in sports that involve a lot of explosive sprinting.
Fun Fact: Lombard’s paradox refers to the paradoxical contraction of both the hamstrings and quads when you rise from squatting or sitting to standing. The two muscle groups are antagonists, which means they usually work in opposition to one another. Apparently this is just efficient human adaptation for being bipedal. Nice.
