"An elite physical trainer came to us with a prototype of what would become the PureTorque, a scientifically proven tool for more effectively targeting the muscles in your torso," writes industrial design firm The Metcalfe Group. "We were able to refine his original idea to create something that was light, easy to use, strong, visually compelling, and, most importantly, incredibly effective."

Early prototypes removed mass from the inventor's prototype and focused how the device should be held and contact the body. This prototype sought to replicate the final materials for the pads and was adjustable to make sure we got the size, shape, and ergonomics just right. Once this was approved through testing with users, we 3D scanned the prototype for use in the next phase.

Once the function and ergonomics were worked out, we created concepts to explore aesthetics and manufacturing methods. These started with hand sketches then were developed further in CAD iterations.

In order to keep the device as light as possible while ensuring it was robust enough to handle the toughest workouts from professional athletes, we ran numerous finite element analysis (FEA) simulations that tested its strength digitally. This allowed us to iterate quickly and fix any potential trouble spots before moving to more expensive and time intensive CNC prototypes and production tooling.

EMG testing (used to measure muscle activity) was done using a CNC machined prototype to measure the PureTorque's effectiveness. These scientific tests showed a 40%-75% increase in utilization of core muscle groups, leading to a more effective workout. After the design was thoroughly vetted, we moved to production using die-cast aluminum.

The Metcalfe Group was relied on to take the product all the way from sketches and rough prototypes through manufacturing sourcing.

Tyreek Hill, one of the fastest players in NFL, endorsed the product, saying "The very first moment I used PureTorque I thought, 'Damn, this thing is different.' I have been hooked ever since."

You can see more of The Metcalfe Group's work here.