RICHMOND, Va. — Three times a week, Robbie Norris, a lean, 50-year-old yoga teacher, hops into his blue 1992 Volvo station wagon with his yoga mat and heads to his class in a drab brick building.

He barely glances at the barbed wire as he strides through the metal detector. He exchanges his driver’s license for a visitor’s pass, navigates a labyrinth of hallways, security guards and the buzzing and clanking of gates, and makes his way to a windowless room.

A dozen women, scarred, tattooed and in blue and yellow jumpsuits, are waiting, splayed on donated yoga mats under harsh halogen lights.

“What’s up, Robbie?” said Kim Alexander, 31, an inmate at the Richmond City Jail who is charged with violating her probation and is in addiction treatment, as she reached out to touch her toes. In minutes, the other women, whose crimes include embezzlement and parole violations, were inhaling, exhaling and deep into a series of vinyasa and warrior poses, with only the clank of the guard’s keys outside to disturb them.