Intensity In Weight Training

Having a solid grasp of the General Adaptation Syndrome (part 1 and part 2), we can begin to explore the main training variables we need to manipulate in order to control the effects of our workouts.

Understanding how these elements work and how to use them properly can dramatically influence the physiological response of our bodies to the training stress and help us to deliberately address the consequent adaptations toward our actual goals.

Because every sport is a different story, though, in this article I will only cover intensity in the context of resistance training and weight training.

So, without further ado, let me introduce one of the most important yet misunderstood elements in training programming – Intensity.

What is Intensity?

Giving a definition of intensity is not an easy job. Partly because of its frequent misuse by coaches and athletes, partly because of the emotional load that is commonly attached to the word.

Everyone in the fitness industry seems to be talking about intensity, but what is it exactly?

Can it be defined? And if so, can we measure it?

Many of us would be tempted to describe intensity based on subjective feelings such as fatigue, muscle soreness or our state of psychological arousal. However, from an objective standpoint, intensity refers to either the intensity of load or the intensity of effort.

The intensity of load is relative to how much we are lifting and is measured in terms of maximal repetitions.
The intensity of effort is relative to how close to our maximal effort a certain weight is and is measured with a scale of perceived exertion.

Both concepts have been elaborated upon in the literature and proved their worth, but we will focus on the intensity of load because of its simplicity and popularity and leave intensity of effort aside for the moment.

Defining intensity with respect to a maximal repetition may be somewhat simplistic, but it let us quantify intensity, an extremely useful thing to do.

However, simply knowing how much we are lifting is not enough to have an idea of the level of intensity we are working at. Most of the times, when intensity is being discussed, we are actually talking about relative intensity.

Relative Intensity

When treated in absolute terms, weights are no more than numbers. Knowing how much can someone lift can certainly give us an idea of his or her level of strength, but doesn’t tell us much about the actual potential of the athlete.

We all know well that what feels heavy to someone may feel not so heavy to someone else. Judging only from the numbers, we can definitely tell what an athlete can do but not how the athlete perceives it. This is the difference between an absolute perspective and a relative perspective.

If intensity is our concern, the focus shouldn’t be on how much we can lift but rather on how heavy does the weight feel to us. How hard is it? How close are we to our limit? And, again, how do we measure it?

In order to answer these questions, we have to put things in perspective. We need something to which compare our numbers. We need to define an individual standard to which relate the amount of weight lifted each time.

The 1 Repetition Maximum

In weight training, this standard is usually the 1 Repetition Maximum (1RM).

On a given exercise, the 1RM is the maximum amount of weight we are capable to lift for a single repetition while maintaining good form during the execution.

A couple of things to notice.

First, we are not deliberately stopping at one repetition. The weight we are handling is so demanding we’re physically impeded to complete a second repetition. A true 1RM allows one single repetition and that’s it. If we could do more, we’re simply not using our 1RM.

Second, we can determine a 1RM for each different exercise.

The 1RM comes in handy when we want to quantify relative intensity on a given exercise, and we do that by dividing the weight we are using by our 1RM on that particular exercise.

This calculation is known in mathematics as standardization and allows us to express any weight we lift as a fraction, a percentage of our 1RM. The closer our weight is to the 1RM, the higher intensity will raise. By definition, lifting our 1RM shoots intensity up to 100%.

As An Example

We have three different lifters (A, B and C) who are close friends and always train together. They all have been into weight training for a while and they regularly test their maximal weights, but are a little confused when it comes to determine intensity in their training.

They would like to know which one among them is training with more intensity. Looking at their training logs we are able to find their recently tested 1RMs, as well as their current training weights (numbers in the figure below). We have everything we need.

So, which one of them is lifting with more intensity?

Giovanni Baldi Intensity example

Note: the calculations are done in kg for my convenience but even when done in lb won’t change the results as they are expressed in %. Also, we can apply the following reasoning to any exercise we want, as long as we know our 1RM on that exercise.

Lifter A

Lifter A is using a 40 kg training weight and his recently tested 1RM on that lift is 50 kg. What is the intensity?

As we know, simply knowing he is using 40 kg is not enough. We want to relate that number to his standard (1RM) and determine relative intensity instead.

Relative intensity (A): 40 kg / 50 kg = 0.8

Now, if Lifter A lifts 40 kg, there are two things we can rightly assert. Lifter A is lifting at 80% intensity and Lifter A is lifting 80% of his 1RM.

Both statements are correct and basically say the same thing. The only difference is that the first one brings its focus on intensity, while the second one on the weight lifted.

Intensity is expressed as a percentage (80%), 80%1RM is instead an actual weight. In fact, 80% of 1RM (in this case 50 kg) equals 40 kg.

Lifter B

Lifter B is stronger than Lifter A. His training weight is 60 kg, and his tested 1RM is 70 kg.

What is the intensity now? Is it higher or lower when compared to the former?

I’m sure some will be tempted to answer that intensity is higher in this second case because the weights involved are heavier, but don’t be misled by the numbers.

Remember, before making any comparison we must divide the weight we are using by the 1RM.

Relative intensity (B): 60 kg / 70 kg = 0.85

Intensity is 85% and is in fact higer than the former, but not because 60 kg is heavier than 40 kg. The reason because intensity is higher is that Lifter B is working closer to his maximum potential (1RM).

Also, instead of saying that intensity is 85% we could say that Lifter B is lifting 85% of his 1RM. It’s just the same thing.

Lifter C

Let’s consider Lifter C now. Lifter C is training with the same weight as Lifter B (60 kg) but he has the best 1RM of all three, a whopping 80 kg.

If we reason in absolute terms, Lifter C is the strongest lifter. If we had the three friends enter a competition and had them lift the heaviest weight possible, he would probably be the winner.

But what about intensity? Is he training as hard as his peers?

Just like before, we have to divide the training weight by the 1RM.

Relative intensity (C): 60 kg / 80 kg= 0.75

Intensity is 75% only and, despite being the strongest and using the same weight as Lifter B, Lifter C is lifting with the lowest intensity.

In this sense, he is outclassed even by Lifter A who is only capable to lift a much lighter weight (40 kg < 60 kg) but is training closer to his maximum potential (85% intensity > 75% intensity).

By the way, even if 85% intensity is unarguably greater than 75% intensity, it would be a mistake to assert that 75%1RM is less than 85%1RM because these are actual weights and refer to different 1RMs!

In fact, 75%1RM (60 kg, the weight lifted by Lifter C) is obviously greater than 85%1RM (40 kg, the weight lifted by Lifter A). Standardization only works with intensity. We must compare apples to apples.


The example above is only a hint but hopefully helped to give a more scientific perspective on intensity. Without knowing anything but their recorded weights, we’ve been able to determine and compare the intensity level in the training of three perfect strangers.

Going back over it, it’s essential to avoid making the wrong assumption that intensity always has to be high. High-intensity training doesn’t necessarily mean training better. It simply means training heavy and while unquestionably being a great tool, it’s just another tool in our toolbox.

The percentage-based method we have just used is probably the simplest method to quantify intensity. It has been around for decades in training programming for all strength sports and is still extremely popular to these days.

As a method, however, it’s not perfect.

In future articles, we will study its strong and weak points, and how it behaves when compared to other methods to measure intensity.

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