If traditional supine bridges become too easy, you can try to progress to the one leg version. This exercise is going to work your glutes like none other. Your hamstrings and lower back are also heavily engaged during this exercise. The single leg bridge requires an advanced level of fitness. This is generally true in cases where one leg is being used to support the majority of your bodyweight. Another factor that makes this exercise difficult is that it is perform using a Swiss ball (unstable surface). Instructions for this exercise are listed below:

Lie down on a workout mat. Place your hands on either side of your buttocks, palms facing down. Rest the heel of one leg on the Swiss ball, then lift the opposite knee in toward your chest. Once in position, elevate your hips as high as you can. Pause for about 2 seconds, then slowly lower your hips back to the mat. When your hips are elevated, only your shoulders, arms, and head should touch the floor.