From KitUp:

“The suit mimics the action of leg muscles and tendons so a soldier’s muscles expend less energy,” Ignacio Galiana, a robotics engineer working on the project, said in the Army’s release.

Soldiers wearing suit prototypes along with battle gear tested the suit at Aberdeen Proving Ground, Maryland. Researchers collected data as the soldiers walked on treadmills and a three-mile course on paved roads and rough terrain.