would it be ok to do single bulgarian lunges (this is when u have ur trailing leg on a bench) instead of lunges or step ups? cuz i find these easier to do with good form...
Also how many times a year can the SFM be used?
stationary lunges and step ups (especially if performed with out excessive foward lean and knee angle near 90 at hip height) are more hip dominant movements. Bulgarian Squats tend to be a more quad dominant movement. That said I'd suggest asking Waterbury the next time he does Prime Time... it's his program after all.
Bulgarian Split Squats aren't the best substitute, but they're sufficient.
what to be the best substitute then?
Why not work on your lunge and/or stepup form?