Piston rowers use two hydraulic cylinders for resistance which are adjustable for intensity usually by moving a clamp up or down a shaft. These machine are the most challenging on a muscular level, so if your goal is to strengthen the shoulders, upper back and arms, this is a great choice. Most piston type rowers are compact and lightweight, so they fit into small spaces and are easy to move around and store. Some have articulating arms that will allow a little more freedom of movement to suit different peoples' arm lengths etc.
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Rowers of Different Types