Rowing

Rowing, like cleans, can be a movement that goes against our untrained instincts. As human beings, we like to pull on things, whether it is pulling a bar up to us, or pulling a handle on a rower. What actually gets us the best results, however, is using our legs and hips as our main power sources.
Rowing is a chain reaction. It starts from your feet, pressing HARD against the foot plates. Then, as you drive yourself backward, the wave of energy comes up your legs, straightening your knees as you fully extend your legs. The energy then moves into your hips, which pop open in a powerful movement, causing you to lean back slightly. Then, and only then, do your arms, shoulders and upper back contribute the final snap of the bar to the chest.
If you bend your elbows too soon in rowing, it is the equivalent of pulling on the bar in the clean. You have immediately broken the chain, skipping your legs and hips, and depriving yourself of your potential power.
Courtesy of CrossFit LA.com

I really find this article very interesting, because most people use their arms for all of the pull. I personally own a C2 rower and love the thing, but if you are not training with efficiency than why train at all. So think next time you get on the rower at the gym.