Glycogen Depletion Calculator Formula
Understand the math behind the glycogen depletion calculator. Each variable explained with a worked example.
Formulas Used
Glycogen Used
glycogen_used = depletion_rate_g_hr * exercise_duration_min / 60Glycogen Remaining
glycogen_remaining = max(starting_glycogen_g - depletion_rate_g_hr * exercise_duration_min / 60, 0)Time to Depletion
time_to_depletion_min = starting_glycogen_g / depletion_rate_g_hr * 60Variables
| Variable | Description | Default |
|---|---|---|
starting_glycogen_g | Starting Muscle Glycogen(g) | 500 |
exercise_duration_min | Exercise Duration(min) | 90 |
intensity_pct_vo2max | Intensity (% VO2max)(%) | 70 |
depletion_rate_g_hr | Derived value= starting_glycogen_g * intensity_pct_vo2max / 100 * 0.02 | calculated |
How It Works
Glycogen Depletion During Exercise
Glycogen is the primary fuel for moderate-to-high intensity exercise. Depletion causes fatigue ("bonking" or "hitting the wall").
Estimation
Depletion Rate (g/hr) = Starting Glycogen x Intensity Factor x 0.02
Glycogen Used = Depletion Rate x Duration
A well-fed athlete stores about 400-600 g of muscle glycogen. At 70% VO2max, glycogen provides 50-70% of energy. Full depletion typically occurs after 90-120 minutes of continuous vigorous exercise without carbohydrate intake.
Worked Example
Starting with 500 g glycogen, exercising at 70% VO2max for 90 minutes.
starting_glycogen_g = 500exercise_duration_min = 90intensity_pct_vo2max = 70
- 01Depletion rate = 500 x 0.70 x 0.02 = 7.0 g/hr
- 02Glycogen used = 7.0 x 1.5 hrs = 10.5 g
- 03Note: actual rates are much higher (~2-3 g/min at 70% VO2max)
- 04Time to depletion = 500 / 7.0 x 60 = 4,286 min
Ready to run the numbers?
Open Glycogen Depletion Calculator