[Rob W]

take for example the average bodybuilders' arm of 17", add 70% and she gets a 28.9" arm!!

Ah, but you're talking circumference, not volume. A 17" arm circumference (assuming a circular arm cross-section for the sake of simplicity) would give a cross-sectional area of 23 square inches. (work it out yourself if you don't believe me)

Increasing that by 70% gives us an area of 39 square inches, which when run back through the formula gives us an arm circumference of a bit over 22 inches.

Impressive and damn near mind-blowing on the smaller frame of most fbbs, but not quite as extreme as you calculated.

RobW the party pooper.