Hard to say. Some people with massive biceps have had a large gap in the insertion area. Long biceps sometimes do not have a large peak. A bicep with a very pointy peak can really increase the measurement. Where as an arm without the peak would have to fill in all that empty space (around the peak) with actual muscle. So the shape can make the arm measure deceptively larger and look bigger. Just by having a peak. Not neccesarily a more powerful arm though.
Its hard to say if density of the muscle is something that can be trained for, or pre determined by your body. Theres not alot of information on that. Density would not make a bicep bigger though. Just harder. A big puffy arm can measure massive. Look at the synthol arms. Technically people that have fat hanging off thier arms can easily break 23 inches as well. It depends on what standards you set in place.
KILL THAT SHIT
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