When it comes to quads, I think many people rely on leg extensions to engage their muscles. While leg extensions are good for developing and strengthening the mind-muscle connection (as you're able to see the muscles firing while performing the exercise) extensions can be hard on your knees especially when using heavy weights and performing lots of reps. Our main goal is to achieve an ideal physique while training without injury, and to enjoy a lifetime of training!
Landmine squats are my favorite exercise for quads. If you're not familiar with a landmine squat, it's performed with a bar placed in the corner of the gym (like a t-bar row). You face the corner and lift up one end of the bar to chest-height directly in front of you. Next you lean into the bar slightly, keeping your feet shoulder-width apart. As you squat, keep your elbows in front of you and under the weight. Your upper body/chest should be upright, and your knees should be behind your toes.
