Make no mistake, there are many other critical factors involved – training consistency, volume, exercise selection and load, among them – but in my opinion, intensity is all too often the biggest difference between a program that produces results and one that doesn’t. Bottom line, many people just aren’t working hard enough in the gym.

Powerlifters and other strength athletes often discuss intensity in terms of the amount of weight lifted – the heavier the load, the more intense a set is. This is one way to look at it, but when I talk about intensity I’m not necessarily concerned with how heavy the weight is. In my mind, intensity is more or less about two things: (1) training to muscle failure and (2) limiting rest periods between bouts of exercise (sets).

Simply put, a set taken to absolute muscle failure – where you physically can’t do even one more rep with that weight – is more intense than a set stopped short of failure where you could have done another couple reps. Likewise, three sets of 10 reps performed with 100 pounds is more intense when you rest 30-45 seconds between those sets versus 1-2 minutes.

That’s a basic explanation of training intensity, but it doesn’t stop there. Intensity can be taken to the next level by experienced lifters to maximize results by taking sets past muscle failure.

I talk about training past failure all the time, and virtually all of my programs on JimStoppani.com incorporate this premise. There are several specific training techniques I use to train past failure to boost intensity, and I’ll cover them all in detail in the coming weeks and months on GNC.com.

The first such technique I’ll touch on is drop sets. Here are all the pertinent details on one of my favorite methods for sparking muscle growth and fat loss in the gym.

What it is: A set where, after reaching failure with the initial load, the weight is immediately decreased and reps are performed to failure once again without resting. The set is either finished at this point or multiple drop sets are performed, where the weight is decreased further and failure is reached each time at the lighter resistance. In essence, drop sets allow you to reach muscle failure multiple times in a given set.

Why to do it: Drop sets allow you to take your muscles past failure on a given exercise and extend a set without resting, which increases intensity to that muscle group for gains in size and definition. If you have a weak body part that could use some extra attention, drop sets are ideal. As I mentioned above, the less rest you take between sets, the higher the intensity. With drop sets, rest periods are nearly non-existent.

How to do it: Dropping the right amount of weight is key, as is exercise selection. If you don’t lighten the resistance enough, you’ll only be able to do a few more reps, if that; if you drop too much weight, your muscles won’t be challenged enough to get the full benefit of the technique.

For example, if you failed at, say, 10 reps with the initial weight, you’ll want to fail at around that rep count on subsequent drop sets – at 8-10 reps rather than 3-5. To achieve this, a good rule of thumb is to decrease the weight by 20%-30% for each drop set, as research confirms this is the best weight range for optimizing results.

The best exercises for drop sets tend to be dumbbell, machine and cable moves, where weight can be decreased quickly to minimize rest time. With dumbbells, picking up a lighter pair of weights only takes a few seconds. On machines and cables, moving the pin up on the weight stack is a quick change as well.

For an example of how to incorporate drop sets into a workout, here’s a sample biceps routine:

In future installments of this “Muscle Booster” series, I’ll cover more of my favorite past-failure techniques. Stay tuned for those.