The hip joint allows a big range of movement. The muscles around it have to cope with a lot of stresses and pressure as the hip supports your bodyweight and the massive force that comes from the large muscles of the leg.
The muscles in the hip and bottom are very strong and very powerful. They have to be to keep your hip in place, stopping it from dislocating from the extra movement in the joint.
During movement, especially running and jumping, the force on the body multiplies many times and your hip must be able to cope with these forces repeatedly. When a client of mine points to where their pain is, especially lower back pain, a lot of the time the problem stems from the muscles around the hip and bottom.