I recently took a week off, a few weeks earlier than I'd planned, due to overtraining. My muscles were not recovering, my joints were getting sore, I felt totally exhausted.
In a recent thread, one fairly prominent T-Nation poster mentioned that if you're developing injuries or becoming overtrained, you're training incorrectly. This made me think...
When I looked back at my training log from the weeks before my week off, I was shocked. I have a tendency to slowly but surely increase volume of sets and reps (along with weight) over the course of my program (against my trainer's recommendation I should add). The volume of my program had gradually ballooned to what could be considered retardedly inappropriate for anyone not using gear and spending all their non-gym time eating and in active recovery.
"Thanks, Training Log" - if only I'd paid closer attention to you before! Let this be a lesson to me and others: keep a training log, pay attention to it, listen to your body, and if you mess up, figure out what went wrong and don't repeat the mistake. Thanks to my log, I have a better grasp of my training tendencies and my physical limits.
Conclusion: I still think taking a week off every 12 weeks or so is mentally and physically beneficial. BUT, if you're training correctly and building proper recovery time into your program (such as unloading weeks), your week off will not be absolutely necessary to prevent injury and breakdown, but will instead be a tool to enhance optimal growth and recovery.
Just wanted to share!