The key hip stabiliser is the gluteus medius. As you can see in the image above, this is the lateral buttock muscle. The ideal movement for strengthening this muscle is a combination of both abduction (lifting the leg sideways) and external rotation (rotating the knee outwards). The side leg lifts that you often see people doing in bum burning gym classes is actually just targeting the TFL, a short muscle that sits at the top of the outer thigh. What we’re after is a movement that takes the effort further backwards towards the back pocket area of the gluts.