The main target muscle in the Hip Bridge is the erector spinae which runs from your neck to your tailbone. Doing this exercise stretches and engages your hip abductors, gluteus maximus, and hamstrings. On the other end of the movement, the rectus abdominis, obliques, and quadriceps get a workout due to the need to stay stable.
If you are feeling adventurous, you also try adding the Marching Bridge and the Single Leg variation. But don’t get carried away, master the basic bridge before progressing.
A healthy balance of hip strength and mobility is very important to ensure everyday stability and also to prevent overuse and athletic injuries. Achieving this balance isn’t a problem if you keep it in mind, don’t sit too much for too long, and occasionally weird out your coworkers by laying down in the conference room and doing some of these hip bridges!
More hip strength info in my article called 3 Hip-Strengthening Exercises for Power and Mobility