Summer slimdown season has hit the W mag office—everyone is trying various cleanses and classes from Organic Avenue to Ritual Cleanse, and Core Fusion to Physique 57. I’m approaching it the old fashioned way with good old interval training—more specifically, spinning. And I recently encountered the monster of all spin classes, called “Barton biking,” at David Barton Gym.

The class begins in a weights studio and focuses on abs for 15 minutes. While I am a true believer in the fact that I can do 15 minutes of just about anything, instructor Cory put that to the test. Immediately following abs we corralled into the spin studio for 15 minutes of heavy climbs. Then it’s back to the weights—this time with a focus on arms and then legs. We go back and forth for an hour and half in a sweaty daze with the vague awareness that we will eventually “look better naked,” as the gym promises. When asked how he came up with the combination class gym owner David Barton says, “combining spinning and pumping iron was a total eureka moment for me…like peanut butter and chocolate.” When I asked if he had any tips for my summer slimdown plan he replied, “avoid peanut butter and chocolate.”