The Hip Thrust exercise is great for working the butt muscles through a large range of motion.
Just like the Hex Dumbbell Glute Bridges from a few weeks ago, altering the foot position changes the emphasis of muscles being worked. That is why this is a great variation to try.
One tip I would suggest though is that the dumbbell can be prone to sliding on the floor so I would place it against a wall for this exercise.
• Begin sitting on a floor with a bench behind body. Feet should be either side of a hex dumbbell, squeezing into it. Knees out to the sides where they should remain during the exercise.
• Ideally bench height, when seated, should be at shoulder blade height. If bench is higher, begin exercise with butt off floor.
• Brace abdominal muscles and keep braced throughout exercise. Arms can be lightly held in front of body or resting on bench for additional support.
• Begin movement by breathing out and squeezing glute muscles hard whilst driving through feet to lift hips up towards ceiling.
• Shoulder blades and upper back should rotate around edge of bench as hips raise up.
• Continue raising hips until knees - hips - shoulders are in a straight line. Do not over extended lower back to lift higher.
• Breathe in and reverse motion back to starting point.
This is my, mostly, Personal Trainer musings and information which I hope you'll find helpful!