Planning

Detraining Decay Estimator

Estimate how much of your 1RM a layoff costs, by weeks off and training age, and roughly how long it takes to get it back.

Result

1RM after layoff

145.7kg

Total loss

2.9%

Average loss per week

0.72%

Weeks to regain it

2 wk

Exponential approach to a floor set by training age.

Wk 0Wk 2Wk 4

Predicted 1RM (kg)

145.7 kg

Education, not medical advice. The result comes only from the published formula and your inputs. How we check our formulas.

Formula Detraining Decay Formula
Detraining decay: strength −5-10% by week 4, −15-20% by week 8. VO2max −7%/week initially. Mujika 2010 meta-analysis.

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12 min read Detraining: Endurance Declines Faster Than Strength
Detraining endurance declines faster than strength: VO2 max drops ~7% per week early (Coyle 1984); 1RM holds 2-3 weeks, then 7-10% per week (Andersen 2005).
7 min read Detraining Decay: 4 Weeks Off for a 3-Year Trained Lifter
Detraining math: 150 kg 1RM after 4 weeks off for a 3-year trained lifter loses 2.9% to 145.7 kg. Retraining 2 weeks to peak, the decay curve, and gaps.

The same calculation as a JavaScript module you can import. It runs where you import it, with no request, key or rate limit.

import { compute } from "https://aifithub.io/engines/detraining-decay.js";