At five thirty on a rainy Monday morning in October, Robin Lockwood ran the five miles from her apartment to McGill’s gym in Portland’s Pearl District. For decades, the Pearl had been home to dusty, decaying warehouses. Then the developers moved in. Overnight, most of the grimy, run-down buildings were replaced by gleaming high-end condos, trendy restaurants, and chic boutiques. McGill’s was on the ground floor of one of the few old, brick buildings that had escaped gentrification. It was dimly lit and filled with the rank odor you never found in modern, air-conditioned workout emporiums.