The hamstrings cross and act upon two joints - the hip and the knee.
They extend the hip, flex the knee and rotate the lower leg inward when the knee is bent.
The hamstrings also extends the hip as when beginning to walk; both short and long hamstring heads flex the knee and outwardly rotates the lower leg when the knee is bent.
The hamstrings play a crucial role in many daily activities, such as, walking, running, jumping, and controlling some movement in the trunk.
Just walking, running and jogging are simple ones but, there are many ways to exercise your hamsting
You definitely use your arm muscles ALOT when it comes to beam and bars. You also use your calve muscles when floor excersizes are involved. Not saying that's it, but those are the most dominant ones used.