Today I want to cover proper and improper exercise technique for the split squat. I’ll go ahead and note up front that everything I’m going to discuss would apply to the myriad lunging variations as well. The only difference is the added component of movement (forwards, backwards, alternating or whatever).
Recently the split squat in one form or another has come sort of the forefront due to a rather popular strength coach’s belief that the split squat (more specifically a rear foot elevated split squat) can and should replace back squatting for athletes. While I won’t go that far, the split squat can certainly be a useful movement in many situations.
One is when a bilateral leg imbalance, that is a strength differential between the right and left legs, develops for some reason. The split squat is one of many ways to go about correcting this. A second place where the split squat can be useful (and this seems to be the main thrust of the strength coach mentioned above’s argument) is when the low back is limiting squat poundages. Since there is far less low back involvement (as a function of both lighter loads and a more upright torso) compared to back squatting, split squats and their variants can be used to either limit low back stress or as a secondary movement for legs after the low back has been fatigued (e.g. after deadlifts when something like squatting would go poorly because the low back will give out).
Additionally, in situations where a lifter either must use lower weights (e.g. they only have access to a limited amount of weight as dumbbells for example), a split squat can still provide some overload to the legs while requiring less absolute load. There is also some interest in ‘unloading the spine’ for athletes and, again due to the lower absolute loads used combined with less forwards lean, split squats would be a way of achieving that.
I would note that some lifters can use loads in the split squat that actually approach their back squat numbers, this is especially true if they actually squat to parallel or below; so the premise that a split squat automatically lightens the loads used or needed is not necessarily correct. There are two major reasons for this apparent contradiction: how can someone possibly use more weight in a single-leg movement than a double leg movement.