Before we can get into the specifics of this program, we must first define training density, which is the result of looking at two very specific factors of training: volume and duration. Volume is your total workload or how many sets and reps you perform in a given workout; duration is the length of time your workout lasts. By combining these two, we arrive at your training density.

By increasing the amount of work you do in a given amount of time, you also enhance your ability to do work or what's known as improving your work capacity. While some may argue that this isn't necessarily the "best" way to approach hypertrophy, the results are undeniable.

Increasing training density helps to boost both strength and strength endurance, which has implications for muscle growth down the line.

Traditionally, there have been two ways to add to density:

1 Keep Workload Static and Decrease Duration

If you're going to do 10 sets of 10 reps for squats, you're doing 100 total reps. For the sake of argument, let's say you perform this workout in 40 minutes. If I tell you that you must complete that workout in 30 minutes, then that will call for a drastic increase in training density since I'm asking you to complete an identical amount of work in 25% less time. You'd also call me bad names.

2 Keep the Duration Static and Increase Workload

Staying with that same example, you have another option: keep the duration static at 40 minutes, and simply try to do more work within that time period by adding more sets of squats. So rather than just doing 10 sets, you'd aim to complete as many sets as possible, ending up with 12 or even 15 sets. (As an alternative, you could also add more reps to each set.)

In either case, in order to accomplish the goal while sticking to the parameters, you'd have to increase training speed and decrease rest periods. This would also increase work capacity.

I say "method" because this is not a complete fat loss program. This is something you can add to a good program.

In previous versions of density training, the idea was to do a few exercises over a specific block of time and get as many reps per exercise as possible, seeking to beat those numbers in subsequent training sessions. And that's a great method for gaining muscle with fat loss as a consequence.

However, when fat loss is the primary goal, I set things up differently.

As with nearly any great plan designed for drastic fat loss, I look to the old standby: fast-paced circuits. First we select a series of exercises (more on this below) and set them up in a non-competing fashion.

Sounds like just about any circuit training protocol, right? Wrong.

Instead of having a predetermined number of reps, you're going to be performing each of these exercises for time – you simply have to do as many as you can in a given time period. That's where general density comes in. The idea is to perform more reps on each exercise, and that's where the increase in density becomes a factor.

Now, here's where it gets kooky: for your second circuit, you'll be using heavier weight – substantially heavier weight. Rather than just create density circuits, I also took advantage of some other cool things that happen when your body adapts and seems to get instantly stronger.

Not only are we seeking to increase reps, but also increase weight before we repeat a given exercise. Again, this is applied to all exercises within a circuit.

Here's an example to illustrate:

Let's say you did each of the following exercises for 30 seconds* each: overhead press, bent-over row, squat.

* Note: Depending on the exercises, you'll vary the length of time in each set from exercise to exercise and circuit to circuit. Movements with a greater range of motion are done for longer periods of time than those with shorter movements. A chart is provided below.

In performing such a circuit, your results might look like this:

• Barbell Overhead Press: 100 pounds for 12 reps
• Barbell Bent-over Row: 165 pounds for 15 reps
• Barbell Squat: 185 pounds for 11 reps

Your second attempt at that circuit might look like this:

• Barbell Overhead Press: 110 pounds for 15 reps
• Barbell Bent-over Row: 190 pounds for 18 reps
• Barbell Squat: 200 pounds for 14 reps

Now, how is it that you're able to perform more reps with more weight? Simple: your nervous system is kicking ass. Essentially, you're looking to increase neuromuscular activation.

This has been written about fairly extensively, so I won't rehash too much. Suffice it to say that the degree to which you can stimulate your nervous system will have carryover to how much muscular force you can generate. The more neural activation you achieve, the easier it is to push heavier weights, because you'll have an easier time recruiting muscle fibers to do the job.

So the purpose of the set is actually twofold: first, it establishes a baseline number for all exercises, and gives you a frame of reference for performance as well as a goal. Second, and perhaps more importantly, your first set serves as a neurological primer. The weight is relatively heavy on the first set and will certainly start the metabolic processes involved in fat loss, but the best part is you'll be sparking neural activation.

Your first set should be a bit of a feeler set – sort of a working warm-up. The limiting factor should be time, not fatigue.

That is, at the end of the first set on any circuit, the feeling should be, "Oh, damn, I ran out of time; I totally had a few more reps in me!" and not "Holy crap that sucked! I can't believe that was only 30 seconds!"

With the first set, pace yourself and move at a quick but steady clip. Don't speed up as the clock winds down. Instead, just allow your pace to carry you through to the end of the set.

Your second set should be (if you'll pardon my use of scientific jargon) balls to the wall. As you get toward the end, speed up and try to crank out as many reps as possible.

Overall, you'll be lifting more weight for more reps in the same time period for an entire circuit of exercises. A few of these sets and you can see how fat loss – as well as the obvious increases in both efficiency and capacity – would be the end result.

The best part about density training is how fun it is. Because it's challenge-based, you have an immediate goal every set and every workout: do more than you did previously.

Additionally, because it's more of a method than a specific program, this version of density training is instantly adaptable to any type of training. I've provided two density circuits below, one using weights, and one done with just bodyweight (which you can try right now, just to see how awesome this is). However, density training works with kettlebells, resistance bands, sandbags and pretty much anything else you feel worthy of lifting and lowering – like children.

Of course, in the case of a bodyweight circuit, you may be saying, "Wait a minute, Roman! You said we're supposed the increase the weight? I can't do that with bodyweight!" That's a very fair point. You're going to make progress even without a weight increase, but to get the most out of a circuit or workout of that nature, I'd recommend using a harder variation of each exercise for the second circuit (going from regular push-ups to decline push-ups, for example).

The main thing is that you're working harder with each progressive set, aiming to take the greatest advantage of neural activation possible to do more work and burn a metric crap-ton of calories.

As a further benefit (as if you hadn't already figured it out), density training is exceptional for retention of lean mass.

Now that we're clear on the method and the benefits, let's talk training. As previously stated, the goal of this article is to provide you with a training method, as well as a template for creating your own workouts with the density method.

To that end, let's cover some basic rules for creating density workouts.

• Each workout should consist of 2-3 individual circuits, each repeated a second time, for a total of 4-6 performed circuits.
• Each circuit should have no less than 3 but no more than 6 exercises.
• I recommend a push, a pull, a dynamic leg movement (think lunges), a stationary leg movement (stiff leg deadlifts, for example) and some sort of abdominal movement (optional). This is more of a guideline than a rule.

Of course, the most important aspect for density circuits is the length of time for which you perform each exercise. While you can ultimately decide on any interval you want, the chart below illustrates the recommended times that I have found to be most effective for each type of exercise.

General Guidelines for Set Duration

And, because I don't want to leave you hanging, I've also designed two circuits for you to try out. Give'em a shot and leave your thoughts in the discussion section.

Set-up: Perform A1 for as many reps as possible during the prescribed work duration, then rest for the prescribed rest period, recording your reps. After this, perform A2 for as many reps as possible during the prescribed work duration, then rest for the prescribed rest period, recording your reps. Continue this pattern for all exercises. Rest 120s and repeat. For your SECOND circuit, INCREASE the weight by 10%-20% and REPEAT the exercises, trying to match or exceed the number of reps in that same allotted work duration.

Set-up: Perform A1 for as many reps as possible during the prescribed work duration, then rest for the prescribed rest period, recording your reps. After this, perform A2 for as many reps as possible during the prescribed work duration, then rest for the prescribed rest period, recording your reps. Continue this pattern for all exercises. Rest 90s and repeat. For your SECOND circuit, REPEAT the exercises, trying to EXCEED your number of reps from the previous set.

Although manipulating training density was originally designed for hypertrophy, we've seen that with a bit of ingenuity we can further modify the idea for fat loss. In fact, I'd go so far as to say that is one of the best fat loss training methods I've come across. Density workouts are fun, challenging and very effective. Try your hand at designing your own and post them in the forum for some critique from yours truly.