Rear foot elevated split squats, Bulgarian split squats, call them what you may as long as you include them in your training.
Unilateral exercises are important but sometimes overlooked, which is unfortunate because they offer many benefits. They help correct muscle imbalances, improves coordination, uses core muscles, and aids in injury prevention and rehabilitation.
The Bulgarian split squat challenges all the muscles of the lower body and helps improve mobility while at the same time increases stability and balance. It is a great alternative to barbell back squats as it puts less strain on the low back, but can also be used as an accessory exercise to improve your back squat.
Personally, I utilize many different variations of the RFESS in addition to back and front squats. Over the course of the COVID-19 lockdown here in Ontario I did not have access to a squat rack. Instead, I decided to put my focus on unilateral training and slow eccentrics. The RFESS was at first extremely challenging, but quickly became my favourite unilateral lower body exercise.
There are many variations of the RFESS, but before you add external weight should master your own bodyweight first. In my opinion you should be able to perform at least 10 smooth, controlled reps with a pause at the bottom on each leg before grabbing dumbbells, kettlebells or a barbell.
Despite the variation, the set up and execution of this exercise is the same. Using a bench or chair or box no higher than knee height, elevate your rear leg by placing the top of your foot on the bench. I try to find the correct placement of my front leg before doing this, but sometimes I still need to adjust and wiggle around a little bit. I use a narrow stance to avoid pulling groin muscles and lean my torso forward for proper hip hinge mechanics. As I descend my knee travels on tops of my toes, but not excessively past them. You may have to play around a bit and find the ideal position for yourself.
Here are a few of the variations I regularly utilize below. I encourage you to add this exercise to your repertoire.