I use bilateral lifts in my programs, but this post focuses on some of what I emphasize with the execution of single leg lift variants and how, as with most training elements, the devil and adaptation is in the details. There are plenty of exercises out there. How you execute things effects the adaptation just as much as what exercise you choose.
What makes a good single leg squat? What makes a good split squat? What about a lunge? Single leg RDL? What are the common technique flaws and what hints that you should start simpler or the loading is too much?
I’ll start sagittal and Static Supported Work is usually the first stop via a split squat (yes lateral squats (frontal) etc.. fit in this category as well). In the case of the split squat if you can’t do it sufficiently with your feet on the ground you have no business putting your foot up on a bench. Joint alignment foot, knee, and ankle should be there and this means a full foot, good femoral control, a knee that tracks/stays in line with the foot and hip. I go with foot pressure that is full to slightly more heel on the front foot and like to see the back foot well up on the toe (just as you wouldn’t want to see folks pronating or rolling to their toe it makes little sense to see folks block on the heel or cheat to balance by only using the lateral supports of the front foot/ankle and neglecting the medial support chain (the arch of the foot and posterior thib isn’t going to develop by leaning away from it).
Degree of quad or hip dominance will be a product of trunk lean and where the center of mass is and moves in the exercise (tempo as well, spend more time down deep in a good position, more time in the fire for the glute). For flat ground split squats (putting the back or front foot on a step changes things a bit) I most often go with pretty much vertical hips and trunk and a front knee that at the bottom is over midfoot. The back foot (up on the toe) and the ability to relax the back leg so as to not disturb pelvic alignment and unstable the pelvis is key and step length and trunk angle sometimes have to be manipulated for hip flexor tightness issues. Learning from the bottom up (knee on a pad on the ground) is often a good way to teach relaxation in the back leg and the position to push from.
One of the biggest and most often overlooked problems is what the actual pelvis and core is doing in the exercise. As mentioned earlier chest up or vertical may be dead wrong if it’s anterior tilt at the pelvis with ribs up and spinal extension. I like single leg exercises a lot for keeping things in balance and strengthening stabilizing muscles, but in single leg work a pelvis that is rotating anteriorly and laterally tilting (spinal extension above, closed chain adduction below) pretty much guarantees underdevelopment of the glute function and stabilization chain many are after here. You’ll see this a ton as people load too much too early or put the load in the wrong place (some motor challenged folks may even need goblet style loading initially). I like to see a solid core just as in bilateral exercise with good anterior and posterior core contribution.
As you move the above dynamics you have your lunges. Some folks take very quickly to lunging and others need time in split squatting to develop the stability and motor machinery to lunge. Some folks even require corrective exercise interventions to get the right things working in the split squat or lunge pattern. I generally start with reverse lunges in the loading realm (and will stick with those for brevity). With the moment of pure single support on the step back and return the function of the lateral subsystem (foot, adductor, glute, ql/core) is challenged more. Load too much too soon and you’ll see instability in the pelvis and you’re not getting the muscle function you’re after (you can’t shoot a cannon out of a canoe and a glute doesn’t work too well on a pelvis that has no stability). I again favor midfoot/ or over ball of the foot for knee positions (I use reverse lunges as a mixed to more posterior chain dominant element most often). The key to getting this loading position and postures talked about above is the first move is backwards and down of both the pelvis and the ribcage (ie the whole solid trunk form the pelvis up); and that you aren’t just stepping backwards. You want active loading of the front leg while moving the hips down and behind the front foot which sets up a position to extend the leg and hip. Often folks reach from the rear foot vs stepping the body back/down and you end up with anterior tilt very early (chest up spinal extension to fake upright) and poorer posterior chain loading. Another common era is just stepping back and down without actively loading the front leg (double problem here with lack of eccentric/stabilization work for the lead hip and too much weight ends up on the back foot in the bottom which usually causes pelvis unleveling on the return as the weight and stability isn’t loaded in the place you need to push and have stability from). Pushing down and back to come forward again and stand up you want to see that good stability again up and down the chain including the pelvis. I really like to see a rock of a trunk, pelvis to head, and the leg doing work on it to move the body. If that’s not happening it needs more coaching (sometimes repetition with GS), adjustment (coaching and often less load), or regression. I also want to see people finish the lunge on the concentric. It’s not about getting your feet back together but bringing the leg into a position of loading in flexion in front of the body and extending it fully down and back under the body. If these things are happening I’m getting the training I want out of lunges.
So how you do you develop better lunges. If folks aren’t broken or big corrective exercise messes (some need remedial and corrective work and not just more lunging) patient loading is the name of the game. The load may seem light as you get athletes lifting, but patience wins out over too quick a progression particularly in exercises with instability. You can still challenge folks with tempos and reinforce with larger volumes in GS circuits (just because it’s a circuit doesn’t mean anything goes. Quite the contrary, you want quality even when loading with more speed and appropriately challenging fatigue). The systems develop good balance and harmony if the work is neat and it’s allowed to grow that way. It’s tempting to overload the single leg stuff early as bilateral work may require more growth time to load substantially for some developmental athletes. I view this as a mistake. People and athletes aren’t training or competing for just six weeks of their lives, you’ll get to better end points where you can load how you need to and get what you want out out of that loading if you let things develop harmoniously.