Work your outer thigh muscles by bringing your feet closer together. To make this variation more quad dominant, place your narrow stance lower.
Also, note that you’re already focusing on the quad muscles by placing your feet closer together, which makes this an excellent variation for those who aim to build up this muscle in particular.
Place your feet slightly higher on the footpad to activate your glutes and hamstrings, which will take the stress off your quads. This is an excellent substitute for hamstring curls and deadlifts. Also, most people will observe that this position enables them to lift the most weight.