How do comparisons between Perry's physique on the one hand and images of weightlifters and jockeys on the other hand help establish Perry's physical challenges?

Perry likes to lift weights but he looks disproportionate because he does not work his legs. He is short and his legs are undeveloped,

Perry would have neatly fitted into a delicate lady's dancing slippers; when he stood up, he was no taller than a twelve-year-old child, and suddenly looked, standing on stunted legs that seemed grotesquely inadequate to the grown-up bulk they supported, not like a well-built truck driver but like a retired jockey, overblown and muscle-bound. (1.19)