Strength Training Like a Scientist with INOL Values in 2020

Where did INOL Values Originate?

INOL values were originally developed with Prilepin's Chart in mind. A.S. Prilepin was a researcher and coach of elite Olympic weight lifters in the 70's and 80's. Through Prilepin's research, he developed a chart to be used as a guideline to help in creating the optimal workout load or stimulus (from a volume and intensity standpoint) for these competitive weight lifters. It's still being used with tremendous success today. However, because it was primarily developed for competitive Olympic lifters it may not be the ideal guide for athletes or lifters that frequently use more than 6 reps in their workouts.

Prilepin's Chart

Percent of 1 Rep Maximum Reps Per Set Optimal Total Reps Range of Reps
55% - 65% 3 to 6 24 18 to 30
70% - 80% 3 to 6 18 12 to 24
80% - 90% 2 to 4 15 10 to 20
90% 1 to 2 7 4 to 10

What are INOL Values?

As a result of the challenges with Prilepin's Chart, a man named Hristo Hristov developed something called INOL values. INOL stands for Intensity for the Number of Lifts. Hristov uses a simple equation that mathematically evaluates an individual routine. It is an excellent tool that helps to quantify the overall difficulty of a routine and workout. We use the INOL equation for both individual exercises and weekly accumulated totals in every workout on

An important point to bring up here is that designing workouts isn't all about the math. There is an art to program development that also takes into account many other variables that have a huge impact on what a workout is ultimately doing to your body.

These variables include: time under tension, rest periods between sets and exercises, exercise selection (squats vs. lunges vs. triceps pushdowns). Even how the exercises are sequenced in the workout can have an impact. Squat before Hinge? Push before Pull? Multi joint before single joint, etc. With that being said we must also understand that there really should be some amount of organization or science to your workouts in order to give yourself the best chance of developing and getting better. Each and every program is carefully designed to balance the science and art of effective strength training.

If you already use, you will know we have a visual week difficulty cue for each week of training. This is simply something like: Very hard, Very Easy, Moderately hard, etc. Doing this gives you an idea of what's coming. INOL values help to quantify this level of difficulty and ultimately helps to set the periodization "map" for your training schedule.

Is it always perfect? No! A medium hard workout on 2 hours of sleep can quickly become the most brutal thing you ever did. But, the program structure still has to be developed because as a regular human being, and probably not a professional athlete, we don't always know when life, jobs, family, school, injury or whatever may get in the way. If, or better yet, when this happens, has some tools that can help you auto-regulate your workouts. Click here to learn more about these tools.

How does the INOL Value Formula Work?

The basic formula is:
Total reps divided by (100 - Intensity)
Intensity is based on a tested or estimated 1 rep maximum (1RM) strength level for a specific exercise. Let's look at 10 reps at 65% of 1RM:

Step 1

100 - 65(%) = 35

Step 2

10 / 35 = .28

The INOL value for this exercise is .28

Now the same process with 6 reps at 80% of 1RM:

Step 1

100 – 80(%) = 20

Step 2

6 / 20 = .3

The INOL value for this exercise is .3

Finally, 3 reps at 90% of 1RM:

Step 1

100 – 90(%) = 10

Step 2

3 / 10 = .3
100 – 90% = 10 3 / 10 = .3 INOL

The INOL value for this exercise is also .3

You can see that even though each set is different they all have INOL values that are very similar. The INOL value shows the similarity of the overall difficulty of each of the set and rep combinations even though the phases and subsequently the reps, and intensities are different.

Are there guidelines for INOL Values?

Yes! Here are some single workout and weekly total guidelines for INOL values based on Hristov's guidelines:

Single Workout INOL Guidelines

INOL Score Single Workout Routine Guidelines
< 0.4 Very easy, too few reps or sets, not stimulating
.4 - 1.0 Optimal if you are not trying to accumulate fatigue
1.0 - 2.0 Tough but good for overall loading phases
> 2 Pretty brutal, very limited use

Weekly Workout INOL Guidelines

INOL Score Weekly Guidelines for an Exercise or Muscle Group
< 2 Easy, doable, good to do after hard weeks or competition
2.0 - 3.0 Difficult but good for overall training phases
3.0 - 4.0 Very hard, lots of fatigue, good for shock cycles
> 4 Only for crazy people!

Keep in mind that the values above do not include any warmup sets. We decided to include everything so the warmup sets in our workouts are part of the INOL total. As a result, our values will be slightly higher overall. We also use a slightly broader categorization (7 instead of 4) to coincide with our Workout Difficulty Levels.

Are there workout and weekly guidelines for INOL Values?

Yes! Here are some INOL guidelines that we use to establish Workout Difficulty levels in Keep in mind that these are guidelines and will vary somewhat in our programs that use Olympic Lifts compared to the programs that use more single joint oriented exercises like triceps pushdowns.

Single Workout Difficulty INOL Guidelines

Workout Difficulty Range
Very Easy < 0.63
Easy 0.64 to 0.74
Moderately Easy 0.75 to 0.84
Moderate 0.85 to 1.13
Moderately Hard 1.14 to 1.23
Hard 1.24 to 1.40
Very Hard > 1.4

Weekly Total INOL Guidelines For a Muscle Group

Workout Difficulty Range
Very Easy < 1.23
Easy 1.24 to 1.34
Moderately Easy 1.35 to 1.91
Moderate 1.92 to 2.81
Moderately Hard 2.81 to 3.00
Hard 3.10 to 3.73
Very Hard > 3.73