Designed for on water rowers, the Dynamic RowErg better simulates the physics experienced while rowing a racing shell and the "dynamics" between the boat and athlete. On the Dynamic erg, a user's body mass is relatively stationary while components of the machine actively move in response to the rowing motion. This is similar to the way a lightweight rowing shell moves around the rower's body. The Dynamic RowErg is recommended only for people who row on the water.