The problem: a number on paper does not tell you how hard to work
Most programs look like this: squat, 3 sets of 10. It seems precise. It is not. Ten repetitions with a weight you could have lifted 25 times is a warm-up. Ten repetitions with a weight you could only just lift 11 times is a very hard set. Both are written as 3 sets of 10, and they produce very different training.
In the last two lessons you learned that volume is how much hard work you do and intensity is how demanding each piece of work is. This lesson covers the variable that connects them and that many programs leave out: effort, meaning how close each set takes you to the point where you could not do another good repetition.
Effort is one reason two people can follow the same program and get different results. Lesson 12 showed that training history, sleep, nutrition, stress, genetics and many other factors also play a part. But effort is one you can see and change today. One person works hard enough to give the body a reason to adapt. Another either coasts or grinds every set into the ground and cannot recover. Neither is following the program as intended, because the program never said how hard to work.
The simple answer
Effort is how close a set comes to your limit. Two simple tools let you describe it and plan it:
- RIR (repetitions in reserve): how many more good repetitions you could have done when you stopped. Stop with two left in the tank and that set was 2 RIR.
- RPE (rating of perceived exertion): a 1 to 10 score of how hard the set felt. In strength training it is usually tied to RIR, so an RPE of 8 means about two repetitions left.
A good program tells you not only the sets, repetitions and load, but also the effort target, such as 3 sets of 10 at 2 to 3 RIR. That one addition makes the prescription fit you on the day, whatever weight that turns out to be.
How the scales work
The repetitions-in-reserve version of RPE used in resistance training looks roughly like this:
- RPE 10 (0 RIR): no more repetitions possible with good form. Maximal effort.
- RPE 9 (1 RIR): one more repetition was possible.
- RPE 8 (2 RIR): two more were possible.
- RPE 7 (3 RIR): three more were possible. The weight still moves at a steady speed.
- RPE 5 to 6 (4 to 6 RIR): clearly working, but plenty left.
- RPE 1 to 4: light to very light. Warm-ups and technique practice.
This scale was described for resistance training by researchers who linked RPE scores directly to repetitions in reserve[1], and coaches have since set out how to use it to plan and adjust training[2].
For walking, cycling, running and other conditioning, RPE is used on its own, without RIR. A simple version: 3 to 4 out of 10 is easy and you can hold a full conversation; 5 to 6 is moderate and you can speak in sentences; 7 to 8 is hard and you can manage a few words; 9 to 10 is close to all-out. Lesson 20 used this kind of scale for easy and harder cardio sessions. The idea is the same: a shared language for how hard something is.
Good repetitions, not any repetitions
In APEX, repetitions in reserve means repetitions you could do with the same control and range of motion. If the next repetition would only happen by twisting, bouncing, shortening the range or losing your brace, it does not count. This is sometimes called technical failure, and for most people most of the time it is the limit that matters. It links back to lesson 35: control comes before load, and it also comes before effort.
Why effort matters
- It shapes the stimulus. A set does little for strength or muscle if it is far from your limit. Hard-enough sets are what lesson 40 counted as volume.
- It shapes the fatigue. Sets taken to your absolute limit tend to cost more recovery than sets stopped a little short. Push every set to the edge and fatigue can build faster than you recover.
- It adjusts to the real you. Your strength is not the same every day. Poor sleep, stress, a long shift or a fasting day all change what a given weight feels like. A load fixed in advance can be too heavy on a bad day and too light on a good one. An effort target lets the load move with you. This is called autoregulation: you regulate the load based on how you are performing today.
This is the phase 5 lesson in action. Two programs with identical exercises, sets and repetitions are different programs if one is done at 4 RIR and the other at 0 RIR. Effort is a training variable, just like volume and intensity.
What the evidence says
APEX keeps evidence, coaching principle, the APEX framework and your individual decision apart. Here is what sits in each layer.
Research evidence
- The RIR-based RPE scale is usable and meaningful. In the study that introduced it, ratings were related to how fast the bar moved, and experienced lifters rated their effort more accurately than newer ones[1]. Certainty: moderate. It shows the scale works as a tool, especially with experience.
- People are imperfect at guessing their reps in reserve. A review that pooled studies on predicting repetitions to failure found that people often misjudge it, tending to underestimate how many repetitions they have left, and that guesses were more accurate when made closer to failure[3]. Certainty: moderate, from a modest number of mostly small studies. In plain terms: when you think you have 3 left, you may have more.
- You do not need to train to failure to make good progress. A meta-analysis comparing training to failure with stopping short found no clear overall difference in strength or muscle growth[4]. Research on muscle growth also suggests that sets should get reasonably close to failure to be effective, although the exact best distance is still being studied and may differ between people and exercises. Certainty: moderate.
Coaching principle
From that evidence, a practical rule follows: most working sets for strength and muscle can sit somewhere around 1 to 4 repetitions in reserve, with lighter efforts for learning and warm-ups, and true failure used sparingly and only where it is safe. Because guesses are imperfect, people need to calibrate: occasionally check their guess against what they can actually do. These are coaching interpretations of the research, not precise findings.
APEX framework
APEX treats effort as a dose matched to stage, goal and skill. Effort is not proof of commitment. Harder is not automatically better; the right effort is the one that creates adaptation you can recover from and repeat.
Your individual decision
Where you sit within those ranges depends on your experience, the exercise, how well you control it, your recovery and your goal. That is your decision to make, using your logbook to see what works.
The APEX principle: effort follows competency
In lesson 35 you learned that each movement moves through Learn, Control, Load, Strengthen and Perform. Effort follows the same order.
- Learning a movement: keep effort low (about 4 to 6 RIR). You are practising skill. Hard efforts break technique before it is learned.
- Controlling and loading it: work around 2 to 4 RIR. Hard enough to build capacity, far enough from the limit to keep every repetition clean.
- Strengthening and performing: you can work closer, around 0 to 2 RIR on suitable exercises, because control holds up under fatigue.
This also explains why the exercise matters. Taking a chest press machine or a cable row close to failure carries little risk: the machine guides the path and you can stop at any point. Taking a heavy barbell squat or deadlift to failure carries more risk and more fatigue, and many lifters keep these at 1 to 3 RIR even when advanced. Supported tools, which earlier lessons defended as legitimate at every level, are also the safest places to learn what hard effort feels like.
Effort at different stages
- Restoration: effort is guided by comfort, tolerance and, where relevant, the advice of a qualified healthcare professional. The aim is to finish sessions feeling able to do more. RPE on the 1 to 10 scale is useful here, mostly kept light to moderate.
- Foundation: learn the scales. Most sets at 3 to 4 RIR, with honest notes. Newer trainees often stop well short because hard effort is unfamiliar, so occasional safe calibration on a machine helps.
- Transformation: most working sets at 1 to 3 RIR. This is where effort starts to drive visible change in muscle and strength, and where poor effort control often helps explain a stall.
- Development: effort targets are written for each exercise, and some programs use a top set at a set RPE with lighter sets after.
- Performance and Mastery: RPE becomes a fine adjustment tool for heavy, specific work and for managing fatigue across a training block, including easing off in planned lighter weeks.
A real-world example
Picture a 40-year-old office worker who has trained twice a week for two months. Her program says 3 sets of 10 on leg press. She has used the same weight since week three and the sets feel fine. Her strength has stopped improving.
She starts writing an RIR guess after each set. Most sets she rates as 2 RIR. Then she tries a calibration set: on her last set, she keeps going with control until she cannot press another full repetition. She does 17. Her 2 RIR sets were really about 7 RIR.
Nothing about her exercises, sets or schedule needs to change. She adds weight until 10 repetitions honestly leave about 2 to 3 in reserve, and her progress starts again. This pattern fits what the research on prediction accuracy suggests: people often have more left than they think[3].
The opposite pattern also exists. A keen lifter treats every set as a test, grinding the last repetition of every squat. He feels beaten up, sleeps poorly and stalls. For him, the fix is to stop each set at 1 to 2 RIR and use the saved energy to recover and progress.
How to learn RPE and RIR
- Rate every working set. Straight after the set, ask: how many more good repetitions could I have done? Write the number next to the weight and repetitions.
- Watch the speed. When repetitions slow down noticeably, you are usually within about 2 to 3 of your limit. When a repetition grinds, you are at about 1 or 0.
- Calibrate safely. Once in a while, on the last set of a safe exercise (a machine, a cable exercise or a bodyweight exercise you control well), keep going until you cannot do another good repetition. Compare that number with your earlier guess. Avoid doing this on heavy free-weight squats, deadlifts or presses without a spotter, safety bars and plenty of experience.
- Adjust the load, not the effort target. If 10 repetitions leave 5 in reserve, the weight is too light for the target. If you cannot reach 10 at the target effort, the weight is too heavy.
- Repeat. Accuracy tends to improve with experience[1]. Give it several weeks.
What people commonly get wrong
- Ignoring effort completely. Following sets and repetitions without asking how hard they were. This is a common reason simple programs stop working.
- Rating how tired they feel, not how many repetitions were left. Sweat, breathlessness and burning are not the same as being close to your limit.
- Treating hard as better. Training to failure on every set is not a badge of commitment. It is a high dose that most people do not need[4].
- Never calibrating. Guessing for months without ever checking keeps the guess wrong.
- Using effort as a reason to skip. Autoregulation means lowering the load on a hard day, not abandoning the session. A lighter session done is usually better than a perfect session skipped.
- Applying failure to skills still being learned. Hard effort before control breaks the movement you are trying to build.
What not to copy
You will see videos of advanced lifters grinding maximal repetitions, collapsing after sets or following programs written almost entirely at RPE 9 and 10. Some of these people are highly skilled at exactly those lifts, with years of calibration, coaching and recovery built around their training. Their effort level fits their stage and goal. It is not evidence that maximal effort is required, and copying it as a beginner or intermediate mostly copies the fatigue and risk without the preparation. Copy the principle instead: effort is planned, measured and matched to the person.
A note on health and medication
Some health conditions and some medicines can change how effort and heart rate feel during exercise. If you have a health condition, are pregnant or recently gave birth, are recovering from injury or take regular medication, ask a qualified healthcare professional what effort levels are appropriate for you. This article is general fitness education, not medical advice.
Where this fits in APEX
In the APEX loop (Assess, Program, Execute, Measure, Adapt, Progress), effort ratings belong to Execute and Measure. They tell you how a session actually went, which makes the Adapt step honest. A logbook with weight, repetitions and RIR shows whether you are progressing, coasting or overreaching. Within a training season, the Learn phase usually uses easier efforts, the Overload and Amplify phases bring efforts closer to the limit, and the Deload phase lowers them again before you Reassess.
Your next best step
For your next two weeks of training, write an RIR number after every working set, and once per week do one safe calibration set on a machine, cable or bodyweight exercise to check your guess. That is all. You do not need a new program. You need to know how hard you are actually working in the one you have.
Once effort is visible, the next question is how often to train each muscle and movement. That is the next lesson: Training Frequency.
