To really build up your upper body muscles, you can perform seated cable rows, bent over barbell rows, bent over dumbbell rows and iso-lateral low rows.
While performing seated cable rows, you can achieve maximum effectiveness, by way of pulling down the weight towards your stomach, and if possible, bring it on even lower, all the way, at the level of your legs. Basically make sure that you get the weights as low as possible, to build up the entire bulk of your back. Many aspiring body builders commit the mistake of letting their arms and shoulders do all the work, while their back relaxes in bliss. But if you are truly committed to the goal of building up your upper body, focus on your back and ensure that it is your back that is doing the work. Your posture should be upright or tilted backwards for maximum effectiveness, and don’t swing around or tilt in all directions. Keep a firm straight posture.
Bend over from the level of your waist. Hold your upper body parallel to the ground. Slightly bend your knees. Ensure that your back is arched while its horizontal and you are now ready for bent-over barbells. Now pull up the bar. If you pull it up towards your chest, it trains the upper part of your lats muscles. If you try and pull it up towards your lower abs or legs, then it is responsible for training the lower part of your lats. Training the upper lats, adds a whole lot of width to your lats muscles. Training the lower lats fine-tunes the V-taper of your back muscles.
For the bent over dumbbell rows, assume the same position as that of the bent over barbell rows. The only variation in bent over dumbbell rows in terms of effect is that it isolates the lats from all the other muscles to which the lats are locked onto. The variation in terms of physical position and posture is that all other aspects being the same as bent over barbell rows, one arms and one knee are rested on a bench. The other leg is responsible for holding your entire body against that of the ground. The arm on that side is responsible for working out with the dumbbell. You could either pull up the dumbbells towards your chest level or your stomach level.
Make sure you do not make any jerky or swinging movements with your arms, shoulders, back or legs. Also make sure that you do not perform both the bent over barbell rows as well as the bent over dumbbell rows in the same work out session, as that would put too much stress on your lats. Do either bent over barbell rows or bent over dumbbell rows during any single work out session. Also focus on your lats, and ensure that it is your lats that are getting worked out during the bent over dumbbell or barbell rows, and not your arms or shoulders.
Finally, in the iso-lateral low rows, you are using any machine, which isolates the lats (iso-lateral). For this purpose using any kind of a grip and rowing with both your arms, will help isolate your lats and work them out.
Make sure you work out regularly with the above mentioned exercises of seated cable rows, bent over barbell rows, bent over dumbbell rows and iso-lateral low rows, to achieve that perfect molding, toning and building of your upper body muscles.