I once knew a skinny bookish looking guy that I met in the Hartford Barbell Studio in Connecticut.......guy could do tons of chins,tons of chins with just 2 fingers,huge weight on pulldowns, and had an insane deadlift and an insane amount of weight used on a plate loaded leg extension machine.......told me he had to stop doing them because he felt that his shins were actually bending................. .......his words,not mine.
He once shook my hand I went down on one knee he had a grip of fucking steel.