The lower-body exercise where you step forward and bend both knees toward a 90-degree angle is a lunge.
In a forward lunge, one leg steps ahead while both knees bend and the body lowers. The front foot remains planted, and the rear leg extends behind, creating a staggered stance. The person then pushes through the front leg to return to standing. Although a 90-degree angle is a useful teaching cue, exact knee and hip angles vary with anatomy, balance, and technique.
Lunges train the quadriceps, gluteus maximus, and hamstrings, while also challenging balance and coordination because the legs work in a split stance. A longer step tends to emphasize the glutes, while a shorter step can place more emphasis on the quadriceps. Bodyweight is enough for beginners; dumbbells, kettlebells, or a barbell can increase the load.
A lunge differs from a squat because the feet are staggered rather than positioned side by side. It also differs from a step-up, where the person climbs onto an elevated platform. In a split squat, the feet remain stationary, whereas a traditional forward lunge includes a step and activates the rear leg as part of the movement.