In previous articles we have described why it is important to know the RM, and how the encoder is one of the best ways to measure the speed of the bar, for after knowing the RM there. But, really, how to predict the RM based on the speed of a submaximal repetition?

RM calculation step by step

In one of the first articles, he explained, very briefly, how placing in a graph the kilos of the surveys (on one axis) and the speed (on the other axis), and putting together with a line the points, we obtained an equation that allowed us to know the RM.

Next, I will describe how the RM is calculated with said graph:

Perfil fuerza-velocidad1.-The first thing we must do to know our 1RM is to incorporate some surveys in a graph in which one of the axes is the speed and the other the weight that we have raised. It will not be difficult, since all the surveys are done with a few kilos and at a specific speed.

2.-Once we have done this, we will notice, how the points form something similar to a straight line, that is, we could draw a straight line above the points, and join them in that way. In many cases we will not be able to unite all, some points will be higher and others lower than this line, but they will be close of the straight line that we have drawn.

3.-If the surveys are in the form of a straight line, the surveys that we would do with other kilos that we have not measured, are somewhere in the line that we have drawn among the points that we have.

4.-In many cases the lines are quite far from the real points we have measured, Our surveys do not form a straight line! Well maybe they should join with a line that is not straight … so that it looks more like the line formed by the points that we have.

(Incised: We can describe how a straight line is with a first degree polynomial, a equation that describes straight lines. In contrast, a polynomial of the second degree, is a line that forms a curve. Therefore, we also know that the polynomials of second degree approach, in many cases, more to the points we have of the surveys.)

5.-Going back to the previous thing, if we drew a line between the points, we could get the polynomial of first, or second degree that describes that line, that is to say, we obtain an equation. And if we have an equation with two unknowns, and we give a value to one of them, We can solve the equation and get the other one. In other words, if we give the speed of a survey to the equation (first incognita), we could get the weight we raise at that speed (second incognita).

6.-Then, if we know the speed at which we raise our 1 RM, or an approximation, we can know our RM that day! Solving the equation with the value we have given it. This is the method that most of the MR calculation devices use to obtain the daily MR.


Although the ideal would be to obtain an ideal prediction of the RM is to obtain the equation on a daily basis, because of the discomfort that supposes we could have a fairly good approximation using the equation of previous days.

Although the accuracy is quite high, it is only a mathematical prediction. There are many factors that influence an RM survey that the prediction of the RM with the speed of execution does not take into account, such as the fear that we may have to fail, a failure in the technique, the accumulated fatigue, an unfavorable environment, or lack of concentration.

. To finish I would like to emphasize that it is a reliable method to know the state of form every day, but I would not use it to know the precise MRI, since there are countless variables that these predictions do not take into account.