Well muscle fatigue won'treally be a problem i don't think because this is my logic: shooting74# with 65% letoff, at full draw i'm still holding back 26#. with an 80# draw with 80% letoff i would only be holding back 16# at full draw. so yes, it would take a little more power to pull the bow back, but in reality with the 80# bow i can hold it longer than my 74# bow. i figured if i could have the extra power and it be easier to pull back, why not do it?