Calculator and how to interpret load

The quickest way to internalize the internal load scale is to play with the parameters. The calculator below applies the formula load = minutes × (intensity / 10)² × CA in real time. Load one of the presets to see canonical cases (heavy squat, plank, running, HIIT, plyometrics), or adjust the values to a scenario of your own. The "Comparar dos ejercicios" (compare two exercises) button opens a second calculator to see two cases side by side. The calculator is currently shown in Spanish.

When you load the presets you will see revealing patterns:

• A 4×8 squat at RPE 7 and a 6×30 s HIIT at RPE 9.5 give similar loads (~4 AU). The HIIT has far less volume, but its near-maximal intensity makes up for it once squared.
• The 10 km long run accumulates ~3× the load of the squat. That makes sense: an hour at RPE 6 is serious work the body feels.
• A 5×1 squat at RPE 10 (1RM) comes out low in AU (~1.3) because it is barely 50 s of active work. The neural stress of a 1RM is always complemented by tonnage and % 1RM, not by AU alone.
• 5×5 box jumps add up to little active work, but their CA of 1.8 puts them on a par with the heavy squat — reflecting the high neural and joint impact of plyometrics.

These contrasts are why AU is never used on its own. It is always interpreted together with external metrics (Layer 2) and derived indicators (Layer 3).

How to interpret the numbers

AU load is relative. What matters is not the absolute value of a session, but the pattern over time:

• Compare between weeks: did last week accumulate more or less load?
• Spot sharp jumps: increasing weekly load by more than 30% over the 4-week average triggers the ACWR indicator.
• Balance planned vs completed: if what you prescribed added up to 50 AU and the client did 25, there is a significant deviation worth a conversation.
• Accumulation vs deload: in a deload week, load should drop to 50-70% of the recent average, not to 90%.
• Look at the three layers together: a session with little AU but very high leg tonnage is not "light". A session with lots of AU but low CA across the board is probably long cardio.

Limitations

• Sets without intensity do not count: if there is no RPE/RIR/%1RM or equivalent reference, that set does not contribute to the total. No default values are assumed.
• CA is subjective: two coaches will assign different CAs. There is no absolute truth. What matters is consistency within each coach's system.
• Maximal strength comes out low in AU: a 1RM set involves very little active time and therefore little AU. The relevant metric for maximal strength lives in Layer 2 (tonnage, % 1RM). AU does not replace it.
• It does not predict individual fatigue: load is a programming and monitoring tool, not a physiological model of the specific client.
• It does not replace observation: if the client accumulates low load but reports exhaustion, AU does not capture it. You have to combine it with subjective feedback (sleep, energy, aches).
• Prescribed rest is not counted: two sessions with the same active work but very different rest periods will have the same AU, even though their real density is different.

What to read next

Go back to the three-layer framework to review how internal load, external metrics and derived indicators fit together. The model's scientific references are on the guide's main page.