Rowing is a low impact activity that uses every major muscle group in your body. With minimal pressure on the joints rowing activates the leg muscles, hips and butt muscles with every stroke. They also work the upper body muscles, strengthening the lats, back, shoulders, rhomboids and arms. The abs are also turned on in the exercise as the rower takes each stroke. Some rowing machines have a magnetic resistance while air rowers have a more natural resistance with the faster you row the harder the resistance. Rowers with Built in programs are the most popular rowing machines as some people tend to get bored on rowing machines so then the programs provide variety and change the levels of resistance automatically.