The deadlift split squat is a great low body exercise if you want to really focus on the quads. This is a constant tension movement – the quads never get a break, and that's great for hypertrophy.
Simply split squat or lunge over a barbell, grab the bar, and stand up. Switch legs and repeat for reps. Focus on your legs, particularly your quads, and minimize lower back action.
As a bonus, this variation requires more torso stabilization so you'll get some core work too.
She did 15 minutes on the elliptical trainer. Then she did arm curls, leg extensions, straight leg raises, and side bends-lots of side bends. In short, she was doing everything wrong.