The Lunge Isometric is a great way to get some serious intensity without needing to actually do any reps.

To Perform get into a lunge position, with the back knee barely off the ground, and front shin vertical. Keep front foot flat with the toes down, and back foot bent without letting the heel touch the ground. This exercise is part of the 50 Body-Weight Workouts E-Book which can be found at the link below!

https://www.bigbendsc.com/store/50-bodyweight-workouts