my biceps are the same size as they were when i was hitting them religiously and all i'm doing is heavy back work and nothing else adn they're still a strong as ever.
Actually that can be misleading, because it takes a lot less to maintain than to build, which doesn't mean compounds would be enough from day one. I don't believe believe that compounds were responsible for most of my development. But they could be enough if done in specific ways that essentially make compounds into at least partial isolation exercises.
They can then be more effective by focusing on certain areas of ROM and form. By doing that further isolation of specific muscles is realized within a compound, This is exactly why it's suggested that compounds like bench press and lat work be made more effective by using certain techniques.
For example, chins work the bis intensely and can be even more effective by emphasizing parts of the ROM and changing the form used. Focusing on the upper range of ROM closer to the bar, rather than lowering all the way down where the back comes into play more is one way.
Another way is to modify form. With chins it's usually suggested to focus on elbow movement in order to focus more highly on the lats rather than arms. Converely, greater arm flection and development is realized by forgetting about elbows and focusing on maximum forearm movement. Focusing on the upper area of ROM on chins also hits the biceps better.
The same rules apply to any compound re: both ROM and form. For example, when Milos and others show had to best do bench presses for chest development, it's the same idea as above-by using scapular retraction the effect is more greatly concentrated on chest, just as the same scapular retraction applies to lat work.
