This style of lunge is actually slightly better than the forward lunge when it comes to building muscle, partly because it's harder to compensate with the lower back, so your form is better.
If your goal is to build your quads, this reverse lunging style also beats the forward lunge, which is better for glutes and hamstrings.
When getting set to do an exercise, there are only two real decisions you need to make, “How Many Reps Should I Do?” and “How Close to Failure Should I Go?” Here’s your guide.