mihailomilovanovic // Getty Images 6 min read FOR LOTS OF guys, the concept of leg day is synonymous with heavy barbells and weight racks. Whether they're using these implements to squat, lunge, or deadlift, they're focused on loading up their lower bodies using just one approach. But you're not always going to have the space, time, and gear to build your leg day workouts around the barbell. Plus, there are plenty of exercises that are better suited to less unwieldy loads. You can use dumbbells to train your quads, glutes, and hamstrings—and they can be just as effective for the progressive overload you'll need to make the muscle, strength, and performance gains you're striving to achieve. You don't even have to feel like you're settling when you opt for the dumbbell section of the weight room instead of waiting in line at the squat racks.…