Training intensity: percentage of 1RM vs proximity to failure and how to increase it

Training intensity at a glance: load and effort

Load intensity vs intensity of effort

In the gym, “intensity” means two things: the load relative to your one-rep max, and effort, meaning how close to failure a set ends. The first is load intensity, given as %1RM; the 2026 ACSM position stand uses it interchangeably with load. Researchers call the second intensity of effort and treat it as a continuous scale, not a failure-or-not choice (Fisher et al. 2022); in the effort and intensity section of this knowledge base we simply call it effort.

With a 100 kg 1RM, 80 kg × 3 and 80 kg × 9 have the same load intensity, 80%, but a completely different effort: the first leaves a lot in reserve, the second ends close to failure. So “3 × 8” with no percentage and no RIR doesn't say how hard a set should be.

Percentage of one-rep max (%1RM)

Percentage of one-rep max (%1RM) is the weight of a set divided by your 1RM, the heaviest weight you can lift once through a full range of motion, multiplied by 100. With a 120 kg 1RM, a set with 90 kg is 75% of 1RM. Kilograms alone are absolute intensity; %1RM is relative intensity.

You don't have to test your 1RM: calculate an estimated 1RM (e1RM) from a heavy set of 3-10 reps in the RIR/RPE mode of the 1RM calculator, which accounts for reps in reserve; a formula without RIR treats the set as one to failure and underestimates 1RM from a set with reps left.

A percentage is based on a 1RM you measured earlier, so it doesn't account for fast changes in 1RM in beginners, fatigue after a hard block or off days (Helms et al. 2016).

How many reps you can do at 70, 80 and 90% of 1RM

A meta-regression of 269 studies worked out how many reps you can do to failure at 70, 80 and 90% of 1RM (Nuzzo et al. 2024). The last column is the %1RM chart by reps and RIR from our calculator.

Sex, age and training experience changed the number of reps little; the exercise and the type of training people did changed it a lot. At 60% of 1RM people did more reps in the squat than in the bench press (Shimano et al. 2006), and on the leg press at 70% of 1RM endurance runners averaged 40 reps and weightlifters 18 (Richens and Cleather 2014). The spread between people grows as the load drops: about 2.5 reps at 80% of 1RM and about 4.4 at 60%. So “3 × 8 at 80%” is a set to failure for one lifter and a set with 3 reps in reserve for another.

The calculator chart assumes fewer reps than the meta-regression, most of all at lighter loads, so a plan based on the chart's percentages usually leaves you more reps in reserve than the chart suggests.

Effort: how close to failure you end the set

Effort is described by RIR, the number of reps left to failure at the end of a set, or by RPE on a 10-point scale, where RPE 8 is RIR 2. RIR 0 is muscular failure; the RIR levels and the choice of scale (RIR vs RPE) have their own pages.

Helms et al. 2016 link the two measures: at 83% of 1RM you get about 6 reps to failure, so 5 reps is RIR 1 and 3 reps is RIR 3.

Intensity for hypertrophy vs intensity for strength

For muscle, the load can be light or heavy as long as the set ends close to failure. For strength, you need heavy sets.

In experienced lifters, loads of 80-100% of 1RM build the most strength (Helms et al. 2016); early on, strength also goes up with moderate loads. On the big lifts, combine the two: the percentage sets the weight, and RIR checks whether it fits the day. The same review gives the example of 3 × 3 at 90% of 1RM with the note “RIR 0-1 on every set”: if you can't get 3 reps, the weight goes down, and if more than 1 is left, it goes up.

The load mainly changes strength: in a network meta-analysis, strength rose most after loads above 80% of 1RM, while muscle grew about the same with every way of training (Currier et al. 2023). Heavy loads, though, need more sets to match moderate ones for muscle, and light sets take a long time, so for hypertrophy the middle of the range is the most convenient (Schoenfeld et al. 2021).

The lighter the load, the more effort matters. In untrained men, leg extensions at 30% of 1RM stopped about 15 reps short of failure gave no significant muscle growth, while going to failure did; at 80% of 1RM, failure added nothing (Lasevicius et al. 2022).

How to increase training intensity

You increase training intensity in two ways: end sets closer to failure, or use a heavier weight for fewer reps, which raises your %1RM (step 4). Adding weight as you get stronger (step 3) is progressive overload: the kilograms go up while the percentage of 1RM stays about the same (ACSM 2026).

1. Log weight, reps and RIR for every working set.
2. If you end your working sets at RIR 3-4, move down to RIR 1-2. Save RIR 0 for the last set of a machine, cable or isolation exercise.
3. Once all working sets reach the top of the rep range at the target RIR, add the smallest weight step, following double progression. The RIR/RPE calculator works out the new weight.
4. On your main strength lift, change the rep range, e.g. from 8-12 to 4-6: at RIR 2 that's about 80% of 1RM instead of 63-74%.
5. If reps have stalled on an isolation exercise or you're short on time, do the last set as a drop set or another intensity technique.
6. Rest at least 60-90 s, 2-3 minutes on heavy multi-joint lifts and 3-5 minutes between sets of 1-5 reps (rest between sets).

On a barbell the smallest jump is usually 2.5 kg: two 1.25 kg plates. With light dumbbells the next pair is a big jump (10 to 12 kg is 20%), so add reps first.

You often read that shorter rest makes a workout more intense. Research shows the opposite: in a meta-analysis of 9 studies, rest periods longer than 60 s produced slightly more muscle growth, probably because you lift less after a short rest (Singer et al. 2024).

Example: the same workout written in %1RM and in RIR

The same workout can be written as a percentage of 1RM or as reps with RIR; the kilograms come from the 1RM calculator chart, rounded to 2.5 kg.

The calculator chart describes a fresh first set, while the RIR target in a plan applies to every set. At a fixed weight the reserve shrinks from set to set; if nothing is left on the fourth set, the weight was too heavy for that day. On an off day, a plan written in %1RM keeps you at 95 kg and the set ends closer to failure, while a plan written in RIR has you lower the weight.

The free 4-day upper/lower plan, intermediate version (from week 2), uses no percentages: the barbell bench press is 3 × 6-10 at RIR 2, and cable and isolation exercises are at RIR 1, because if you misjudge your reserve there and hit failure, nothing bad happens.

Which exercises to plan in %1RM and which in RIR

Percentages suit heavy barbell lifts where 1RM is easy to estimate; RIR suits machines, cables and dumbbells.

Training volume vs intensity, tonnage and rest

Intensity describes a set, while volume, tonnage and rest describe the whole workout.

For muscle, with sets close to failure, the number of sets matters more than the load: according to the 2026 ACSM position stand, muscles grew more with 10 or more sets per week. In SmartWorkout, 4-10 sets (MEV) is the target for a regular muscle group, because that's where each set adds the most growth, but it's a minimum, not a ceiling; the 1-2 muscle groups you want to bring up faster aim for MAV, 10-20 sets. You can count your week in the sets per muscle group calculator.

Common mistakes

1. Sweat and pump as a gauge. Sweat, pump and soreness say nothing about the load or the reps in reserve. Judge a set by %1RM and RIR.
2. Percentages from an old 1RM. A percentage of an old result gives the wrong weight, because 1RM goes up or down (see above). Estimate your 1RM every 4-8 weeks from a heavy set, or add a RIR target to the percentage.
3. The percentage chart as gospel. At the same percentage, people and exercises differ by several reps (see above). Use the chart as a starting point and adjust the weight after the first set.
4. Failure on the big lifts. Failure adds no strength (ACSM 2026), and its advantage for muscle in a meta-analysis was trivial (Refalo et al. 2023); according to ACSM, for some people it may be inadvisable because of injury risk as technique breaks down. On the squat, deadlift and barbell bench press, end your sets at RIR 1-3, and go closer to failure on machines and isolation exercises.

What the research says

Research asks how many reps you get at a given %1RM and what grows: strength or muscle.

It's unknown how many reps you get at a given percentage in most exercises other than the bench press and leg press, and which target RIR works best; most studies involve young men, and studies on women alone are few.

What SmartWorkout logs show about intensity

Lifters in our logs, mostly in Poland, rate heavy sets as close to failure as light ones. We advise otherwise: on the big lifts, 1-3 reps in reserve, and in long sets closer to failure, because at lighter loads you judge your reserve less accurately (Halperin et al. 2022). Every number is based on at least 50 people.

How to set intensity in SmartWorkout

In SmartWorkout you log weight and effort (RIR or RPE) for every working set, and a plan sets the target as a percentage of 1RM, RIR or RPE.

1. Open “Workout Settings” (the settings icon on the workout screen) and under “Effort scale” choose the “Scale type”: RIR or RPE (logging RIR, RPE and tempo).
2. Enter the weight and reps of a working set, tap “RIR” on the keyboard and pick your reserve from 0 to 4 (in 0.5 steps).
3. Check the e1RM next to the set, the 1RM estimated from weight and reps. The app calculates it without RIR, as for a set to failure, so for percentages use a set of 3-6 reps that ended at RIR 0-1.
4. In the plan creator (Workout > My Plans > “+” > “Create new plan”), set the “Load Indicator” to “1RM” to plan in percentages, or to “RIR” or “RPE” to plan effort.

A plan with the 1RM indicator shows the target for each set as a percentage, and you work out the kilograms yourself, e.g. in the plan weight mode of the 1RM calculator.

With Premium, you know what to do next workout: add a rep, add weight or stay at your current target, and the suggestions take your logged RIR into account (progression suggestions).

You can paste this strength day with loads in %1RM through plan import (Workout > My Plans > “+” > “Import plan”); the first set leaves about 2-4 reps in reserve. Raise the percentage by 2.5 points each week (80, 82.5, 85%) if the last set of the previous week ended with at least 1 rep in reserve; if not, repeat the week. That's how the load goes up in linear periodization; after 3-4 weeks, estimate your new 1RM from your last heavy set. The warm-up sets mode of the 1RM calculator lays out the warm-up weights. Import costs 10 AI credits, so the welcome credits cover it.

DAY: Strength A- Barbell Squat | WU 5x1-10 | 4x5 80% 1RM | TEMPO 20X0 | REST 180- Barbell Bench Press | WU 5x1-10 | 4x5 80% 1RM | TEMPO 20X0 | REST 180- Barbell Overhead Press | WU 4x2-10 | 3x6 75% 1RM | TEMPO 20X0 | REST 150