Originally Posted by MikeC
Would you consider this the case for natural bodybuilders who see diminishing returns over time?
Completely. The rule of thumb is that your body will adapt to anything you do that doesn't go beyond your ability to recover. Naturals will still need to continue to expose their muscles to new stimuli over time once their body has adapted to whatever training they are presently doing. Although volume is only one of a number of ways to do this, it is highly effective for bodybuilders because it doesn't effect the CNS like continuing to increase weight, and doesn't effect between set recovery like trying to do the same amount of work in less time.
All forms of progression have their place however, even in bodybuidling. Doing the same amount of work in less time is great for fat loss, and increasing weight is great for building maximal strength, both of which can be important parts of a bodybuilder's training.
The main difference between naturals and those who use anabolics is the focus of the training. The focus of a natural should be on progressing in the big compound lifts while using isolation movements to both compliment the big lifts and build weak areas. This is different from those who use anabolics because they don't need to stimulate the release of natural muscle builders like testosterone and HGH. This is, of course, a generalization and even bodybuilders on anabolics still use many compound movements.
The application of volume, however, has more to do with individual differences as opposed to use of steriods.