What it is: ZeSa Fitness is a low-impact, full-body workout that incorporates core stability training with strength and cardio. Exercises are done on souped-up Bosu-style balls, called Activator Platforms. The platforms, which rotate as well as move front to back and side to side, graduate in difficulty.

The concept: The idea is that by performing exercises while balancing on unstable platforms, all of your muscles (core, secondary, tertiary) are engaged, which increases the difficulty — and the results.

Where did it come from: ZeSa is the brainchild of University of St. Thomas grad Shanti Rainey. An athlete, trainer and yoga instructor, Rainey developed ZeSa (which is based on the Sanskrit word for balance) to allow people of a wide range of abilities to get a full-body workout. “It’s the only workout that gives you complete muscle recruitment without high impact,” he said.

Class motto: Balance is strength, strength is balance.

The workout: Each class member gets a circular mat, which is surrounded by fairly lightweight dumbbells, kettle bells and weighted balls. After a brief warm-up, we started our barefoot workout with a series of traditional moves (kick backs, shoulder raises, squats and lunges), during which we were balancing on one or more Activator Platforms.

The instructor did an excellent job of demonstrating each move step by step, then had the class do a practice run or two before we launched into a series. Other members of the class were supportive and encouraging, and there weren’t any giggles when I made the mistake of placing my platform upside down. The apex of the hourlong class was a plank position, in which each of our hands and feet was balanced on a platform. Sound difficult? It was, but it also was a kick to master it.

What it’s like: In a word: intense. While I was familiar with all of the exercises, having my hands, my feet or both (!) on an unstable surface made each exercise so much more challenging. While I wasn’t dripping with sweat or winded by the end of the class, I felt like I had completed a challenging workout. And concentration muscles were aching.

Who it’s for: Anyone — from beginner to elite athlete — who’s interested in developing fitness and balance without high impact. The class I attended had 20-somethings to 60-somethings, former runners nursing injuries and hard-core athletes.

Who it’s not for: Traditional gym rats who love pulsating music, pounding the floor and competing against everyone else in the class.

Classes: Power, a full-body workout for all levels of ability; Power Pro, for advanced practitioners or athletes; HITT, which involves a series of short, intense periods of exercise followed by a brief rest; and yoga flow.

Cost: The first 30-minute intro class is free. After that, $25 for each single class, $179 for one month of unlimited classes. There also are five-, 10- and 20-class packages.

Where: 1024 Washington Av. S., Mpls. zesafitness.com