No other exercise equipment burns, tones, and works the body as effectively as the WaterRower S1 Rowing Machine in Brushed Stainless Steel with S4 Monitor. Rowing, like other endurance based aerobic activities such as swimming and cycling, has long been recognized as the most complete aerobic exercise. It is a non-impact workout and is naturally smooth and flowing. With the S1 WaterRower, you work 84% of your entire mucle mass – more than any other exercise.