The gluteus maximus and gluteus medius are two large muscles in the buttocks that contribute greatly to forward and upward propulsion, and also to lateral or sideways motion. The gluteus maximus, along with the hamstrings, are recruited in any forward bending movements involving hip extension, resulting in the thigh or top of the pelvis moving backward, such as in step-ups and stiff-legged deadlifts, good mornings, squats, lunges, or traditional deadlifts.
The role of the gluteus medius, on the other hand, is to help steady the pelvis so it does not rotate downwards or sag when the opposing side is lifted or not supported with the other leg. It also assists with lateral movement away from the midline of the body, i.e. moving the thigh outward with hip straight. It lies on the side of the hip directly above the larger, “meatier” gluteus maximus. The gluteus medius can be somewhat neglected in the quadriceps-dominant activities of running, which primarily involves forward movement in a straight line, and in cycling. Sometimes knee pain can be caused by overusing quadriceps muscles when glute
muscles are not “carrying their proper burden.” Article entitled, "Targeting the Gluteus," by C. Schurman, MS, CSCS.
Pictures of some amazing glutes . . .
So, you have something to smile about work your butt off. Let's hit the gym.