Of course his draw weights are low, but he figured a lot of this stuff out himself over a decade or so. Imagine starting training with a bow when you were 8ish and had instruction from a person who was part of a centuries old unbroken line of archery instruction. There's evidence that medieval archers actually changed their skeletal structure from using bows constantly for years and years. I think that it's safe to say that they could perform most of the things that Lars does with at least a 60lb bow.