The back is divided into two muscle groups.
Latissimus dorsi (lats) - These are large triangular muscle that extend from under the shoulders down to the small of the back, and they are also the largest muscles of the upper body.
Spinal erectors - The muscles in the lower back that guard the nerve channels and help keep the spine erect. They are also the slowest muscle to recover from heavy exercise.
Below you will find specific exercises to perform if you find you find you have a weakness to any part of your back or there is a certain part you wish to add more size to.
Lat width: Wide grip pull-downs and chins.
Lower lats: Close gip pulldowns, one arm rows, and pullovers.
Upper Back: Heavy bent over Barbell rows.
Lower Back: Deadlifts, good mornings, hyperextensions.
Middle back thickness: Barbell rows, cable rows, and t-bar rows.
Outer Back: Rows with a narrow grip, such as t-bar rows.
Middle back thickness: Barbell rows,cable rows, t-bar rows.
Here is a sample back workout that should give you some poor results. I believe in training your back with lower reps than with arms etc. mainly because it is such a big muscle and seems to respond quite well to lower reps.
- Lat pulldown or chins for back width and upper lats. 3-5 sets. 6-8 reps
- Close grip pulldown for lower lats, 3 sets, 6-8 reps
- Bent over Barbell rows for thickness of the back. 3-4 sets , 6-8 reps
- Deadlifts for lower back thickness and total body power. 3 sets, 8,6,4