The runner circles the track while the heart-rate ring gauge tracks intensity and the glycogen tank slowly drains as fuel is consumed. Training in higher zones raises heart rate and lactate faster, burning glycogen more quickly; crossing roughly 85% HRmax pushes lactate production past clearance, so it starts accumulating instead of staying flat. Toggling weekly adaptation lets aerobic capacity (VO2max) rise session over session, exactly like real training blocks.
VO2max(t) ≈ VO2max_0 + ΔVO2max·(1 − e^(−t/τ))
glycogen(t) = glycogen_0 − ∫ burn_rate(zone) dt
lactate accumulates when %HRmax > ~85% (threshold crossing)
- Training zone — target %HRmax; higher zones raise heart rate, burn rate and lactate.
- Session duration — how long the runner sustains the session before the tank empties.
- Weeks of training toggle — simulates chronic adaptation, gradually raising the VO2max ceiling over simulated weeks.
- Reset session — refills glycogen and clears lactate/heart-rate to a resting baseline.
Coaches use exactly this zone model to periodize training — mixing low-intensity aerobic base miles with occasional threshold work to raise VO2max without excess fatigue.