Deloading is an essential part of making progress. If we did not need to deload, then we would gain half a pound of muscle a fortnight for the rest of our lives and we would all be walking around with 350 pounds of lean tissue. Obviously it doesn’t work that way. Obviously, your body doesn’t respond the same at week 20 than it did at week 2. You don’t need a scientific journal to acknowledge that.
For enhanced lifters (and that should be all of you reading, because I am definitely not writing for naturals over here), a planned deload is my recommendation because these drugs can be so powerful that they can skew one’s intuition of when a deload is necessary. These drugs can override a lot of psychological and physical signs of when it is time to back off, so if you rely on “listening to your body” then Trenbolone use may have you deload once every 4 years, not 4 weeks. I do not recommend programming based on intuition. Some guys can do it, but many cannot.
I recommend deloading in a scheduled fashion that ignores the signs and symptoms, unless the symptoms are severe and an early deload (or complete break) is required. If you feel energetic the day of your deload, then congratulations. You achieved what many cannot. Feel free to incorporate long, slow distance cardio on these days that do not require a lot of glycolytic work.
There is no cookie cutter recommendation of when to time and how to structure a deload because the requirements and timing of a deload are goal orientated. For the generally prepared athlete however, I do have a cookie cutter recommendation I find to work well for just about anyone with no peaking deadline. My recommendation is as follows:
4 weeks of training, with 1 week of deloading. The deload week can range from 4-7 days completely off or simply reduce volume and intensity by 50% on this week. Whichever option you choose would depend on your age and health status. If you are an ageing person, perhaps consider the full 7 days off with the light aerobic work. If you are a younger and intermediate athlete, perhaps consider only reducing intensity and volume by 50%
Failing to prepare is preparing to fail. Take care of your health and watch the results accumulate. Remember, there are no medals for who goes to the gym the most. There are only medals for those who look and perform the best. In order to look and perform your best, you will need to remain healthy. In order to remain healthy, some form of regular deload will be necessary.