Another negative point for me is the angle of the seat. Unlike the Concept2, it has a slight backward angle, which makes it easier to maintain good form at the end of the stroke. Given that the Waterrower has greater resistance at the catch, it puts more pressure on the lower back at this point making it uncomfortable for people like myself with lumbar spine problems.
From a fitness perspective, the WaterRower Natural works 84 percent of your muscle mass, helping tone and strengthen your muscles while burning far more calories than most other aerobic machines. The exercise is also low impact, as it removes all the body weight from the ankles, knees, and hips, but still moves the limbs and joints through a full range of motion--from completely extended to completely contracted.