When well-developed, this teardrop-shaped quadriceps muscle bulges just above the knee on the inside of the thigh. Bodybuilders love it because it lends a powerful topography to the upper leg. Cyclists love it for the downward force it helps them drive into each pedal stroke. And you should give it more love in every workout because it will make you stronger and more stable in just about every lower body exercise you do.

Like the other three muscles of the quadriceps group (vastus lateralis, vastus intermedius, and rectus femoris), the vastus medialis runs the length of the femur and functions to extend the knee. But heres what makes it stand out: The muscle is the most important knee extensor during the last few degrees of extension. That means it takes the lead during the final push in power-driven, lower-body movements such as running, jumping, and cycling.

The vastus medialis is also critical for stabilizing the kneecap, to which its attached. Thats another reason to give this key quad muscle some extra attention in your workouts: Strengthening it can help reduce your risk of knee injuries, which are among the most common in the weight room. Need a third? Having a vastus medialis that bulges like a second knee will mark you as certified badass.

Your move: Make sure your weekly routine is peppered with squat , lunge , and step up variations, all of which will activate all four quadriceps muscles, including the vastus medialis.

But when performing the exercises, make sure you move through a full range of motion. The vastus medialis reaches peak engagement when the leg is almost fully extended, so if you want to build it up, you need drive forcefully to the top of each rep.