The curious, the skeptical and the hopeful gather at this unusual spot in the heart of TD Tower. For most it’s the promise of a four-minute workout; for others it’s the lure of a gloriously wacky-looking gizmo called the Range of Motion machine, which is a sort of giant recumbent bicycle–rower hybrid with a stair climber grafted on to the rear. Owner and trainer Julie O’Brien promises a four-minute session on the ROM machine is the cardiovascular equivalent to 30 minutes on the treadmill. The physiological how and why is convincingly explained, but the proof is in the pudding: with users having lost upwards of 10 pounds in three months on the four-minute plan, the appeal is obvious even to the doubtful. If the ROM isn’t a strange enough sight, the only other piece of equipment on hand is a tilting, oscillating and vibrating platform called High Intensity Training Vibe, which purports to strengthen, tone and improve circulation. The sensation is akin to standing on a washing machine during a wonky spin cycle, but clients swear by it.