Shred415

Given the choice between running on a treadmill and running in a blizzard, I’d pick the blizzard. Yet Shred415, a fitness studio that teams treadmill running with strength training, is so popular that since debuting their Lincoln Park location in April 2011, owners Bonnie Micheli and Tracy Roemer have added an Old Town studio and plan to open a North Shore branch next winter. Friends rave about the workout on Facebook, and go four to five times a week. Mystified, I signed up for a 6am Arms & Abs class at Old Town.

At a Shred class, you start on either the treadmill—where you’ll run some mean sprints and some even meaner inclines—or the floor, where you’ll do moves incorporating everything from medicine balls to dumbbells to suspension straps. After 15 minutes, you switch. This happens four times (4-15, get it?) to total 60 minutes, otherwise known as the fastest hour of my life. The constant action of changing your treadmill speed and incline at your instructor’s command, while also half-listening to him or her call orders at the floor crew (or vice versa), made every session fly by. The clubby music also helped—I particularly appreciated a pop diva remix of Rihanna’s “We Found Love” with Whitney’s “I Want to Dance with Somebody.” On the floor, I found my arms giving out during bicep curls, but I liked that the workout is built for every fitness level, with the friendly trainers encouraging you to grab lighter or heavier weights as needed and offering modifications on moves. And treadmills, it turns out, can be pretty interesting when you’re revving them up to 12mph or a 14-degree incline—or using the force of your legs to move the belt manually, which was a real bitch. Just when I thought I couldn’t run another step, it was on to the floor. The avid road runner hooked on a treadmill class…who would have thought? 2156 N Clybourn Ave (773-360-8228), 230 W Division St (312-291-8722, shred415.com). One class $24, memberships and class packs available.