1. [Home](https://www.workoutsmart.com/) 2. [Wave Engine](https://www.workoutsmart.com/wave-engine) 3. INOL Guide · Training science # Strength training like a scientist with INOL values How WorkoutSmart measures the difficulty of every exercise, workout and week. [Method by Dan Wirth, MA, CSCS NSCA 2023 College Strength and Conditioning Coach of the Year](https://www.workoutsmart.com/dan-wirth) On this page - [Origin](#origin) - [What is INOL](#what) - [The formula](#formula) - [Guidelines](#guidelines) - [Difficulty levels](#levels) ## 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 weightlifters in the 70's and 80's. He developed a chart as a guideline for the optimal workout load, in volume and intensity, for competitive lifters. It's still used with tremendous success today, but because it was built for Olympic lifters it may not be the ideal guide for athletes who frequently use more than 6 reps. Prilepin's chart % of 1RM Reps / set Optimal total Range 55–65% 3–6 24 18–30 70–80% 3–6 18 12–24 80–90% 2–4 15 10–20 90%+ 1–2 7 4–10 ## What are INOL values? Hristo Hristov developed INOL, Intensity for the Number of Lifts, in response to the limits of Prilepin's Chart. It's a simple equation that quantifies the overall difficulty of a routine. WorkoutSmart uses INOL for individual exercises and for weekly accumulated totals in every workout. Designing workouts isn't all math. Time under tension, rest periods, exercise selection and sequencing all change what a workout does to your body. Dan authors the periodization map for your schedule, and INOL checks that every week scores the way it is labeled. **It isn't always perfect.** A medium-hard workout on two hours of sleep can become the most brutal thing you ever did. When life gets in the way, Power Up and Express It let you adjust the session, and your main lifts stay as written. [How these tools work](https://www.workoutsmart.com/wave-engine#rule-7) ## How the formula works INOL = reps ÷ (100 − intensity) Intensity is a percentage of your tested or estimated 1RM for the exercise. - 10 reps at 65% 100 − 65 = 35\ 10 ÷ 35 = .28 INOL .28 - 6 reps at 80% 100 − 80 = 20\ 6 ÷ 20 = .30 INOL .30 - 3 reps at 90% 100 − 90 = 10\ 3 ÷ 10 = .30 INOL .30 Each set and rep combination is different, but the INOL values are nearly the same. INOL shows similar overall difficulty across phases even as reps and intensity change. > “You're in a GPP phase, volume based, you have a workout that scores a 1.1; 12 weeks later you're in your max peaking phase, you have a workout that scores 1.1. Completely different volumes, completely different intensities, but they were hard.” Dan Wirth · Strength Coach Collective ## Guidelines Hristov's single workout and weekly guidelines: ### Single workout - < 0.4 Very easy, too few reps or sets, not stimulating - 0.4–1.0 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, per 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! Those values exclude warm-up sets. WorkoutSmart includes warm-ups in its INOL totals, so our values run slightly higher, and we use seven difficulty levels instead of four. ## WorkoutSmart difficulty levels Single-workout ranges used to label every workout. They vary somewhat between programs built on Olympic lifts and those with more single-joint exercises. - Very Easy < 0.63 - Easy 0.64 – 0.74 - Moderately Easy 0.75 – 0.84 - Moderate 0.85 – 1.13 - Moderately Hard 1.14 – 1.23 - Hard 1.24 – 1.40 - Very Hard \> 1.40 See INOL on your own training. Every workout and week shows its score. 14-day free trial. [Start 14 days free](https://www.workoutsmart.com/signup)