A seated row machine leaves little room for error. You can use various handles on this machine, and they will still work the same areas of your upper back and shoulders. Lean slightly forward to grab the handles, and sitting upright, without leaning too far back, bring the handles to your chest, keeping your elbows close and back behind you. Do not bend your wrists when bringing the handles to your chest.
Why it works
Rows work many different muscles, thus burning more calories than, say, bicep curls or tricep presses.