What Is RIR?

RIR is a way of measuring relative intensity.

It is useful because we must meet a certain intensity to induce growth, but by not maxing out all the time, we are able to mitigate fatigue throughout sessions across mesocycles.

Essentially, there is a time and place for training to failure, but it should typically not be done early on in a mesocycle.

As the meso progresses, sensitivity decreases and lower RIRs begin to produce more stimulus with less fatigue.

Here we have Mike performing drop set bicep curls in week 4 of his mesocycle.

In the first half of the set he is leaving 2 RIR (or 2 reps in the tank), to preserve his fatigue for the second half of the set in which he drops the weight and performs the movement to 0 RIR (or failure) - giving him an insane bicep pump!