Do you mean 50lb compound? I shoot 55lb recurve and 60lb longbow trad bows (no let off) and will tire after a couple dozen back-to-back shots, but can go all day on my 50lb trad. With more training I will be able to shoot the 60lb all day, as generations of archers have before me. The important thing is to ensure you train - pull the bow each day, a few times a day, and ensure your frame/stance is top. There's no reason a fit man or woman can't pull 50lb+ bows without tiring easily or injuring themselves.
But yep, I agree it's really important to ensure you're never 'over-bowed' when you start out - it's best to start light. It's a shame however (I reckon) to not get into the athletic part of archery, of getting stronger, building up those back and shoulder muscles, to shoot ever-heavier gear. Howard Hill shot 80-100lb trad bows. No reason we today can't do the same, for the fun of it!
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