Two-set prediction of 1 Rep Max

In strength conditioning (weight-based) the one rep max (1RM) refers to the maximum weight you can do ONE and ONLY ONE repetition with.

In a previous article, I listed the many reasons why this number should be kept as an indicator for strength assessment. One shall avoid however pulling that weight because it is heavy and straining, while the same result can be achieved with less weight and few more repetitions.

A plethora of one rep max prediction algorithms can be found on the Internet, but people, including myself a while ago, have been using them with more of less satisfaction.

There is two facts to consider when using those algorithms. First, there is tons of them, using tons of different formulas yielding of course different results for the same set of data in input. A fairly exhaustive state of the art of those methods demon how pointless they are on a quantitative basis. Second, even when you would be lucky and use a “good and serious” calculator based on published statistical research, these are made out of AVERAGES on a large heterogeneous set of volunteers or an homogeneous but not representative set of volunteers. Thirdly, because the muscle groups do not function in the same ways, the studies yield different equations for different exercises. Typically, the formula for prediction of 1RM at the Leg Squat would be very different from that to predict the benchpress 1RM.

In an excellent article on Strength Assessment, Matt Brizcky, health coordinator at Princeton University, states that :

A number of prediction equations have been developed and used to estimate a 1-RM based on the relationship between strength and anaerobic endurance. While some of the equations have proven to be reasonably accurate, one problem with them is that they do not take into consideration individual differences.2,3 (…)

Because of these genetic influences, especially muscle fibers, some people perform either less than or more than 10 reps-to-fatigue with 75 percent of their maximal strength. Westcott reported data on 141 subjects who did a test of anaerobic endurance with 75 percent of their 1-RM.6 (Remember, it has been suggested that an individual could do 10 reps-to-fatigue with this workload.) According to the data, the subjects completed an average of 10.5 repetitions. However, only 16 of the 141 subjects (11.35 percent) did exactly 10 reps-to-fatigue with 75 percent of their 1-RM. Many of the subjects were within a few repetitions of 10. In fact, 66 of the subjects (46.81 percent) were able to do between eight and 13 reps-to-fatigue. On the other hand, 75 of the subjects (53.19 percent) did either less than eight reps-to-fatigue or more than 13. At the extremes, two subjects did only five reps-to-fatigue and one managed 24. (…)

Another approach to attain an individual-specific estimate of a 1-RM is to use a prediction equation. The most frequently used prediction equations are based on the reps-to-fatigue done in one set.2,3 . However, a test using one set does not account for individual differences in anaerobic endurance. A better way to assess muscular strength from anaerobic endurance is to use a prediction equation that is based on the reps-to-fatigue obtained in two sets.


2. Ware, J ., et al. Muscular endurance repetitions to predict bench press and squat strength in college football players. Journal of Strength and Conditioning Research 9: 99-103, 1995.

3. Mayhew, J., J. Prinster, J. Ware, et al. Muscular endurance repetitions to predict bench press strength in men of different training levels. Journal of Sports Medicine and Physical Fitness 35: 108-113, 1995.

Westcott’s research clearly emphasizes the risk taken when using calculators that work for an average. If you looked at the distribution of the statistical sample, you certainly realized how inaccurate such methods may be for you if you do not have the chance to fit the average. Average figures are indeed one of the very typical misuse of statistical studies in everyday life.

Unlike all one-set generalized methods (including those presented by Brizcky) , Brizcky’s two-set method ensures to yield a personalized accurate 1RM as well as being universal, meaning that one can use it fairly accurately regardless of the muscle group and exercise being considered.

I have computed below the two-set algorithm described by Brizcky and I show as well what his older (one-set) algorithm would have given you, just so that you get a feel of the difference.



The Ultimate Guide On How To Start At The Gym

NB: This article is obsolete, use the Two-set 1RM prediction method instead of the calculator mentioned below.

This article will intentionally not be very comprehensive due to the vast amount of information available online. I will therefore insist on what I NEVER find on workout websites.







  6. NUTRITION: Conditions 90% of your workout’s results



If you hit a gym where you know no one, just approach the oldest person you see and ask them to show you around the machines and the weights. People at the gym are very friendly and often very willing to share their knowledge. The older are more likely to be wise and documented, so by choosing them you might learn right away how to do things properly. Okay, now that you know the machines…


What do you want ? Lose fat ? (In this case your only friend at the gym with be the treadmill and bike, forget about the weights) You want a full body workout or want to focus on some parts only ?  What body type are you ? This will condition how fast you gain muscle and how easy it will be to maintain low fat. What is your budget ? Because most gyms have a fee and you may want to supplement your nutrition or buy better foods. Think very well about what you expect from your gym presence, and how much time you are willing to give to it. A workout session can range from 30 minutes to two hours, and people workout from once to 6 times a week in extreme cases. To begin softly, twice a week should be fine, after a while question it and adapt your workout frequency to your objectives and availabilities.

Having clear objectives is the base for motivation.And motivation, when added to discipline, is the base for success.


Now that you know what you want and know the machines and weights, you need to figure out what exercises will make your selected body parts work out.
For this purpose, I will not say more than Youtube and Google are your friends.

Basic vocabulary: Exercise, Set, Repetition.
An exercise defines the position and the gesture that you are going to make. Given an exercise, you can do several sets. A set, as its names suggests, is a series of repetitions that you do in a row without stopping. A repetition is the combination of one flexion and one extension. So if I say “Flat Benchpress, 30kg 3×8” the exercise is “flat benchpress”, the bar + weights will overall weight 30kg, and you will do 3 sets of 8 repetitions (reps) each.

Be curious, learn how the body is made and learn what a good posture is. When you selected your exercises for your personal workout, you need to figure out…


This is precisely the part I will insist on because it is under-documented. It remains however of major importance for you not to hurt yourself, and above all make progress.

Many people (even educated ones…) just lift weights and have not yet understood that there is some elementary chemistry and engineering that rule a workout’s success, and that MUST be understood. Otherwise, it is the same as pressing random buttons on a cockpit; you know it may do something, but you have no idea what it does…

Nothing makes me angrier than websites or forums that answer this question in this fashion: “For biceps beginners should start with 8kgs” .
NO, NO, NO and NO.
Everybody, or shall I say every body is different. From a person to another, different muscular masses can be observed. But even two persons with the same profile may not have the same aptitudes.


Your next question would be “Okay, and HOW EXACTLY am I supposed to ‘find out’ ?”. Well, that is the very question I want to answer today.

You need to figure out your 1RM.
What is that?

The 1RM method is that thing everyone talks about on the net, without ever suggesting it to beginners which is why I am doing it today.

1RM means One Repetition Max. It is the maximum weight that exhausts you after one complete repetition. In other words, with your 1RM weight, you can do one repetition but absolutely not two. This state of muscular exhaustion is often called failure, concentric failure or point of failure. The 1RM weight will trace your progress, and will be the reference for you to vary the weight within your program.

Of course, there are as many 1RM weight values as there are combinations of people and exercises.

In practice, the only big problem is that pulling your 1RM weight can be dangerous, especially for beginners. It is indeed very straining and harmful if you are not well prepared or if do it too often. Hopefully, there is a safe method to figure your 1RM weight out based on your ability with lighter weights.

Here is the method I suggest to find safely what weight to start with:

  1. Take the smallest weight you can find for this exercise or machine.
    It may be way too light for you but do it for these 2 reasons: it not too heavy so it’s safe anyway, and it will warm you up, which will improve your later performance.
  2. If you can do 10 reps and feel you can do more just stop at 10.
  3. Rest 5 minutes, double the last poundage, and repeat Step 2 until you reach your point of failure in less than 10 reps.
  4. For the set that brought you to failure in less than 10 reps, write down the weight used and the corresponding number of reps.
  5. Now enter them in this 1RM calculator.

Congratulations! Now you know what weights to start with.

This method, although safer than using directly your 1RM weight, may cause muscle pain if you do not do this : Remember to WARM UP BEFORE (all the mucles that going to work), and stretch them all AFTER. Do it well and do take the time it needs or you will be sorry. A pill of magnesium after your workout will help avoiding muscle soreness. A rather ectomorphic friend has accepted to experiment this method he was fine because he did so.

Last advice:

Don’t reach failure too often or it will be counter-productive. There should be at least two full days (48 hours) before your muscles can sufficiently recover from the last concentric failure. Muscle fibers are destroyed in a workout, creating new muscle while recovering. If you don’t let it recover enough you will destroy more than you create, resulting sometimes in muscle mass and performance decrease rather than the intended increase.


If you want to maximize the efficiency for a workout you need to set a clear program.

A good workout program will:

  2. Allow you to rest. The muscle is built during your rests and sleep, not at the gym. Working out is like those things that don’t work anymore if you do too much of them.
  3. Increase Intensity (= heavier weights). Many people at the gym keep the same weights and have their little routine. It allows no progress because their body has no reason to create muscle since it has enough muscle for the task you got it used to. Constantly force your body to go beyond what it already can handle. It may seem like you reach limits, but often times we’re standing far behind them. Do more reps, then add weight and so on [1][3].
  4. Be logged. Keep a journal of what you do. This way you will have all you need to change exercises and poundage. It will also display your progress. For this latter purpose I also suggest taking pictures! Because your weight may not show your progress. Typically, you can loose fat and gain muscle at the same time, have the exact same weight as initially, but you may look a lot more sculpted. So do take pictures even if you are not a big fan of them, they may raise your motivation to higher heights.[3]
  5. Change exercises every now and then to attack your muscles differently [2]. Subsequently it will also keep your motivation up by putting some new spices in your workout.
  6. FOR INTERMEDIATES : Alternate different poundage. It does not sound logical at first sight but established research and experiments show that maximum gains are observed when a bodybuilder engages in some easy and medium workouts, alternating them with heavy workouts.


Looking ripe is the combination of two things:

  1. ABOVE ALL : LOW BODY FAT, too often neglected.
  2. High Muscle Mass.

Forget about supplements, it is just rushing and probably taking risks to try and MAYBE get what you are sure to get safely if you keep it easy and do things properly. Unless you really know everything about them. Otherwise I suggest you read this post On Supplementing.

Working out is the science of Strength and Conditioning. It is not sitting down, pulling random weights and swallowing random magic products. The results will be the combination of how smartly you behave at the gym, and more importantly how you behave OUTSIDE THE GYM. Read my article on nutrition.


To maximize the efficiency and encourage faster and better results, you may need to scan your lifestyle for removal of bad habits. Learn how to have the best possible sleep. A good sleep is indeed of tremendous importance as it is a key period of the recovery of your body. Muscle mass creation is in fact a recovery process from the workout. Alcohol, tobacco and drugs (even the soft ones) will also affect your workouts results in a negative way. I really look at being ripe as a health concept more than something purely aesthetic. You look healthy with those visible muscles but unlike a bunch of those monkeys at the gym try to focus also on actually BEING healthy. When you’ll be old and ugly at least you’ll have health left 🙂

[1] Strength Assessment, Matt Brzycki, coordinator of health, fitness, strength and conditioning programs at Princeton University.

[2] Restimulating Progress by changing exercices,

[3] Shorthand Log,