Barbell Back-Loaded Lunges
Unilateral leg training will increase athleticism in most sports and reduce the prevalence of injury due to imbalances in musculature. This lunge variation will develop strength and stability.
Unrack the barbell the same way you would a back squat. Brace the core and contract the back, slowly stepping backwards with one foot. Softly touch your back knee to the floor. The back knee should be aligned with the front leg's heel, still at hip width apart. Be sure that the pushing leg (front leg) is loaded correctly with the hip under the torso, back flat, and rigid core. To stand up, drive your foot through the floor vertically, standing up. Be sure to not press with you back foot or fall forward while standing up. Repeat and switch legs.
Unilateral (single-sided) leg training is paramount to sound movement mechanics and overall leg development. Almost all forms of human movement and sports require unilateral stability (strength), balance, and coordination. Additionally, this is an amazing way to isolate weak quadriceps and glutes in your training programs.
Typically, lunges and their variations can create muscle soreness very quickly due to the isolated movement. For beginners, repetitions of 10-15 steps per leg at lighter loads will increase balance and stability. Once you have learned the movement, you may program these similar to strengthening exercises in a variety of repetition and loading ranges.