In most muscle Thigh exercises, even if you try to isolate a muscle like Quads, all the other muscles, in one way or another, are synergistic muscle (help in the movement). To increase Quad muscle action and strength (even if you don't increase the load) you have to pre-exhaust your other Thigh muscles.
To gain strength is to develop the ability to support and move higher loads than before by recruiting more muscle fibers and to use them more effectively for a short period of time.
You can use this workout as an example to workout your other Thigh muscles such as Hamstrings or Adductors (for Glutes it's a little different because of the amount of different movements that they are involved in and the different parts of the muscle that are responsible for that).
You can also add at the end of the workout exercises for your Legs (Calf and Anterior Tibial)