How to Use RPE in Iron × Violence

Most training advice assumes you can max out whenever needed. But what if you’re tired? What if your grip is shot from sparring? What if you slept badly?

RPE solves this.

Rate of Perceived Exertion lets you train at the right intensity for how your body feels today, not how strong you were last week.

This guide explains RPE in plain language, with no charts or percentages.

What Is RPE?

RPE stands for Rating of Perceived Exertion.

It’s a scale that measures how hard an exercise feels to you in the moment.¹

The most common scale runs from 1 to 10:

1–2: Very easy, barely any effort
3–4: Light effort, could talk easily
5–6: Moderate effort, breathing harder but sustainable
7–8: Hard effort, challenging but controlled
9: Very hard, near your limit
10: Maximum effort, nothing left

The scale was originally developed by Swedish researcher Gunnar Borg in the 1960s for cardio training, but has since been adapted for strength training.²

RPE vs RIR: What’s the Difference?

You’ll often see RPE paired with RIR (Reps in Reserve).

RIR counts how many more reps you could do before failing.³

For example:

RPE 8 = 2 reps in reserve (RIR 2)
RPE 9 = 1 rep in reserve (RIR 1)
RPE 10 = 0 reps in reserve (RIR 0)

Both measure the same thing from different angles. RIR tends to be more accurate for higher-rep sets, while RPE works better for low-rep, heavy work.⁴

For most purposes, they’re interchangeable.

What RPE 6–8 Feels Like

RPE	What It Feels Like	What To Do
6	Moderate effort. Breathing harder but could hold a conversation. Form feels solid.	Use this for warm-up sets, technique work, or volume days when recovery matters.
7	Challenging but controlled. Breathing heavy. Could do 3–4 more reps with good form.	Primary working range for most training. Builds strength without excessive fatigue.
8	Hard. Slowing down near the end of the set. Could squeeze out 2 more reps but it would be tough.	Upper working range. Use for key lifts when you’re feeling good.

RPE 6–8 is where most productive training happens.⁵

Below RPE 6, you’re not working hard enough to drive adaptation.

Above RPE 8, fatigue accumulates faster than your ability to recover, especially if you’re training multiple times per week.

How RPE Differs For Fighters vs Powerlifters

Fighters and powerlifters use RPE differently because their demands are different.

Powerlifters

Train fewer lifts at higher intensity
Rest 3–5 minutes between sets
Can push closer to failure regularly
Goal is maximal force production

Powerlifters often work at RPE 8–9 and occasionally hit true maximal lifts (RPE 10).⁶

Fighters

Train skills daily (sparring, drilling, conditioning)
Accumulate more total training volume
Need grip strength, trunk stability, and explosive power
Can’t afford to be too sore or fatigued for technical sessions

Fighters should spend most gym time at RPE 6–8, rarely venturing to RPE 9.⁷

The difference isn’t about toughness. It’s about managing total training load across all sessions.

Adjusting RPE on Bad Days

RPE’s greatest strength is flexibility.

Your actual strength varies day-to-day based on:

Sleep quality
Stress
Nutrition
Recovery from previous training
Accumulated fatigue⁸

On a good day, RPE 7 might mean lifting 85% of your max.

On a bad day, RPE 7 might mean 75%.

That’s fine.

The goal is to hit the intended stimulus, not chase arbitrary numbers.

If you planned RPE 7 but the weight feels like RPE 9, drop the load. You’re training your body as it is today, not as you wish it were.

Common Errors

Grinding Every Set

If you’re struggling through the last rep of every set, you’re not training at RPE 7–8.

You’re closer to RPE 9–10.

True RPE 7 means the set was hard, but you finish with control. The bar doesn’t slow to a crawl.

Confusing Discomfort With Effort

Burning quads during squats doesn’t mean RPE 9.

It means your legs are working.

RPE measures proximity to failure, not local discomfort.

False Fatigue

Sometimes a set feels hard because you’re unfocused or anxious, not because you’re actually close to failure.

This improves with practice. Over time, you’ll learn to distinguish true muscular fatigue from mental resistance.

Example Session

Goal: Build pressing strength without excessive fatigue

Exercise: Bench Press
Prescription: 4 sets of 5 reps at RPE 7

Execution:

Set 1: 80kg, felt like RPE 6. Increase load.
Set 2: 85kg, felt like RPE 7. Keep load.
Set 3: 85kg, felt like RPE 7.5 due to fatigue. Keep load.
Set 4: 85kg, felt like RPE 8. Accept it. Don’t chase more.

You hit the target stimulus. The exact weight doesn’t matter.

When Not To Use RPE

RPE works best for:

Multi-rep sets (3+ reps)
Compound movements
Intermediate to advanced lifters

RPE is less useful for:

True 1-rep max testing
Brand new movements where you lack reference points
Lifters who consistently over- or underestimate effort

If you’re new to lifting, expect a learning curve. It takes 4–8 weeks to calibrate your perception accurately.⁹

The Bottom Line

RPE 6–8 is the training sweet spot for most people.

It’s hard enough to drive adaptation, but sustainable enough to recover from.

For fighters balancing gym work with skills training, staying in this range prevents accumulating fatigue that bleeds into sparring and drilling.

On good days, RPE 7 might mean heavier weights. On bad days, it might mean less. Both are productive.

Train your body as it is, not as you wish it were.

References

Footnotes

Cleveland Clinic. (2017). Rate of Perceived Exertion (RPE) Scale. https://my.clevelandclinic.org/health/articles/17450-rated-perceived-exertion-rpe-scale ↩
Borg, G. (1970). Perceived exertion as an indicator of somatic stress. Scandinavian Journal of Rehabilitation Medicine, 2, 92-98. ↩
Helms, E. R., Cronin, J., Storey, A., & Zourdos, M. C. (2016). Application of the Repetitions in Reserve-Based Rating of Perceived Exertion Scale for Resistance Training. Strength and Conditioning Journal, 38(4), 42–49. ↩
Zourdos, M. C., Klemp, A., Dolan, C., et al. (2016). Novel Resistance Training-Specific Rating of Perceived Exertion Scale Measuring Repetitions in Reserve. Journal of Strength & Conditioning Research, 30(1), 267–275. ↩
National Academy of Sports Medicine. The Rate of Perceived Exertion (RPE) Scale Explained. https://blog.nasm.org/rate-of-perceived-exertion ↩
Graham, T., & Cleather, D. J. Autoregulation by “Repetitions in Reserve” Leads to Greater Improvements in Strength Over a 12-Week Training Program Than Fixed Loading. ↩
Ouergui, I., Messaoudi, H., Chtourou, H., et al. (2018). The Effect of Short-Term Sport-Specific Strength and Conditioning Training on Physical Fitness of Well-Trained Mixed Martial Arts Athletes. PLOS ONE. ↩
Helms, E. R., Byrnes, R. K., Cooke, D. M., et al. (2018). RPE vs. Percentage 1RM loading in periodized programs matched for sets and repetitions. Frontiers in Physiology, 9, 247. ↩
Ormsbee, M. J., Carzoli, J. P., Klemp, A., et al. (2019). Efficacy of the repetitions in reserve-based rating of perceived exertion for the bench press in experienced and novice benchers. Journal of Strength & Conditioning Research, 33(2), 337-345. ↩