The Complete Exercise   It is rare to find an activity that works as many muscle groups through as wide a range of motion as rowing does. Knees, hips, arms and shoulders will each see 90 - 130 degrees of rotation in every stroke, which is more than you will find in most other aerobic activities. This greater muscle involvement makes rowing a great calorie burner, while also developing flexibility and strength. Rowing is impact-free, and the intensity is completely user-controlled. Concept2 make the best rowing machines and the model E is an outstanding piece of equipment.