How to Use Detraining Decay Estimator
The Detraining Decay Estimator applies Mujika's exponential decay model to predict how much one-rep-max strength you lose across a layoff. Enter your prior 1RM, the number of weeks off, and your training age; the tool returns your predicted 1RM after the layoff as the hero number, plus the total strength lost as a percentage, the weekly decay rate, and how many weeks of retraining it takes to rebuild to your previous peak. It models strength only, not aerobic capacity.
What It Does
Use the calculator with intent
The Detraining Decay Estimator applies Mujika's exponential decay model to predict how much one-rep-max strength you lose across a layoff. Enter your prior 1RM, the number of weeks off, and your training age; the tool returns your predicted 1RM after the layoff as the hero number, plus the total strength lost as a percentage, the weekly decay rate, and how many weeks of retraining it takes to rebuild to your previous peak. It models strength only, not aerobic capacity.
Athletes, coaches, and AI agents who need a quick, reproducible answer with named limitations rather than a generic estimate.
Interpreting Results
The hero number is your predicted 1RM in kilograms after the layoff. The secondary stats show the total strength lost as a percentage, the weekly decay rate, and how many weeks of retraining it takes to rebuild to your prior peak. The methodology page shows the exponential decay constants — understanding them explains why the first two weeks of inactivity cost proportionally more than weeks three and four, and why a higher training age slows the decay.
Input Steps
Field by field
- 1
Enter inputs
Enter your values using the sliders and steppers. Defaults represent a reasonable midpoint.
- 2
Read outputs
Read the hero number first. Secondary stats provide context and ranges.
- 3
Follow
Follow the methodology link for formulas, coefficients, and citations.
- 4
Adjust parameters
Adjust each input one at a time to see how the hero number responds.
Run the same detraining period with your training age set 2 years higher and 2 years lower — if the hero number barely shifts, training age is not the driver; inactivity duration is.
Common Scenarios
Use realistic starting points
FAQ
Questions people ask next
The short answers readers usually want after the first pass.