I squat and deadlift with a barbell regularly. I know how much I can lift with variants of those exercises on a given day. I'd like to use that knowledge to better understand how much I should expect to lift with a weighted lunge.
What is the normative ratio between a lifter's squat and their lunge?
We know these relationships, in broad strokes and with some caveats, between other lifts. The front squat and back squat, the squat and the deadlift, the deadlift and the power clean, and so on all have known relationships consisting of a range of ratios. For instance, a power clean between 40 and 60 percent of one's deadlift is to be expected, and most people's front squat is generally about 80% of their back squat. So: what lunge is to be expected if one can squat X?
Any type of loaded squat and any type of loaded lunge is acceptable, but please be specific: e.g. "barbell back squat to forward-stepping lunge with a barbell across the shoulders" or "barbell front squat to rearward-stepping lunge with dumbbells in the hands". Anecdotes welcome but data welcome more.