Density is one of the great yet underused methods of progression in training.
In the 2nd Edition of Master Keys to Strength & Fitness I label it as one of the secondary methods of progression, but that is only because you must understand the primary methods of intensity, set and volume first.
(This article is a bit older but covers these if you’re new to them.)
So it’s not always needed but can be very helpful in many cases.
Density is all about the density of the work that you do. Typically it is within a time frame.
Let’s say you’re doing pushups. (But could just as well be back squats or gripper closes or single leg deadlifts or whatever, the exercise itself doesn’t matter as the concept transcends specific movements.)
How many pushups can you do in 15 minutes?
Take as many sets as you need but count the total volume within that time frame.
(And the time frame could be 5 minutes, 8 minutes, 10 minutes, 1 hour, whatever.)
As this is about progression, the next time you go to train the same movement, all you do is seek to do more total volume in the same time frame. Thus, your density has increased.
The next time you train after that, you seek to beat the number once again. Doing so, you will get stronger. That is how progression works.
This is one way of doing density. Density can be especially great for both fat loss and muscle gain training. Especially great to go back and forth between two exercises doing so, such as you find in The 80/20 Strength Challenge.
And lately, I’ve been playing with a slightly different format. Running against the clock can be tiring (and stress-inducing).
But there’s a way to progress with density but without facing the clock. And that is to count the number of sets you do but allow for as much rest as you want.
How much volume can you do in five sets?
Then in your next workout, seek to beat that number while sticking to just five sets.
For instance, I’m getting back to doing some weighted pullups. In a recent workout, with 16kg attached I did 6,7,6,6,6 = 31 in 5 sets
And that’s how I notate it in my training log.
Since you’re not up against the clock, and are allowing yourself to rest more, this focuses a bit more on strength building.
You have to be careful the time span doesn’t expand infinitely but otherwise I find this form of density training works quite well.