The muscles of his strong buttocks drove him powerfully against her.

This exercise strengthens the buttocks muscles, which support the back and help you lift with your legs.

Embarrassed, the stranger faced away, the muscles of his buttocks tightening.

Do not contract your abdominal, thigh, or buttocks muscles while performing the exercise.

Slowly tighten your buttocks muscles and hold the position (not your breath) for 5 to 10 seconds.

Her fingertips circled the solid muscles of his buttocks.

If your stomach or buttocks muscles tighten, you are not exercising the right muscles.

With his fingers, he began to work the muscles of her buttocks, while he kept his face impassive.

Tighten the muscles of your buttocks and hamstrings, and hold for five breaths.

"You're killing me," she said on a moan, her fingers tightening, digging into the taut muscles of his buttocks.