Rowing whether competitive and recreational is unique compared to most sports because this type of aerobic exercise gives all your major muscle groups a beneficial workout. Everything from your legs, back, and arms are engaged while rowing. This is a low-impact sport, the rowing stroke is a fairly safe motion, providing little room for the serious injury often found in contact and high-impact sports.
Sometimes, slides are placed underneath the erg to try to simulate the movement of being on the water. It allows the machine to move back and forth smoothly as if there is water beneath you. The slides can be connected in rows or columns so that rowers are forced to move together on the ergometer, similar to how they would match up their rhythm in a boat.