A digital clock on the wall in a Main Street garage blinks down the final seconds of Kristin Bell’s lunch break.
She and others working out at Chattanooga Crossfit sometimes do a workout her trainers call the Murph, named for a Navy SEAL who was killed in Afghanistan.
It includes a one-mile run, 100 pull-ups, 200 push-ups and 300 squats, capped with another one-mile run. And it’s all done as fast as possible.
Ms. Bell is one of 20 people on a recent weekday at Chattanooga Crossfit completing a high-intensity workout before returning to work. Crossfit is part of an emerging trend in the fitness business toward timed, intense workouts.

