The gluteal muscles are a group of four muscles. Three of these muscles make up the buttocks: the gluteus maximus muscle, gluteus medius muscle and gluteus minimus muscle. The fourth and smallest of the muscles is the tensor fasciae latae muscle, which is located anterior (to the fornt) and lateral (to the side) to the rest.
The gluteal muscles
The gluteus maximus is the largest of the gluteal muscles and one of the strongest muscles in the human body. It inserts at the iliotibial band (near the pelvis) and the gluteal tuberosity of the femur(thigh). Its action is to extend and to laterally rotate the hip, and also to extend the trunk.
Exercise and stretching
Any exercise that works and/or stretches the buttocks is suitable, for example lunges, hip thrusts, climbing stairs, fencing, bicycling, rowing, squats, arabesque, aerobics, and various specific exercises for the bottom.
Pilates Deb 
In our practices at FOSTERing WELLNESS we feel strongly about the importance of core fitness and we make core training a part of every patient’s recommended care plan. Here is an article we have up on our website.
http://www.fosteringwellness.net/doctor/chiropractor/10765S/%5Bsitecity%5D-chiropractor/core_strength.htm
Dr. Charles Foster