Two independent, parallel routes consume the same glucose pool. Each has its own maximum turnover rate (Vmax, glucose molecules/s the pathway's enzymes can physically process) and its own fixed ATP yield per glucose:
Glycolysis (cytosol, no O2 needed):
yield = 2 ATP / glucose — LOW yield
Vmax = enzyme/GLUT1-limited — can be made HIGH
Oxidative phosphorylation (mitochondria, needs O2):
yield = 30 ATP / glucose — HIGH yield (~15x)
Vmax = mitochondrial-mass/ETC-limited — stays LOW
The Warburg-shift slider allocates glucose supply between the two: allocGly = shift × supply, allocOx = (1-shift) × supply. Each pathway can only process up to its own Vmax — rateGly = min(allocGly, Vmax_gly), rateOx = min(allocOx, Vmax_ox). Total ATP production rate is the genuine sum of both branches:
ATP_rate = rateGly × 2 + rateOx × 30
Because oxidative capacity is biologically capped low (mitochondrial density, O2 delivery), a pure-oxidative allocation tops out at Vmax_ox × 30 ATP/s no matter how much glucose is available. A pure-glycolytic allocation instead scales with min(supply, Vmax_gly) × 2 — lower yield, but with no low ceiling. Once Vmax_gly exceeds roughly 15 × Vmax_ox (the yield ratio) and glucose supply is generous enough to feed it, shifting allocation toward glycolysis raises total ATP/s past what oxidative phosphorylation alone could ever reach — the real Warburg trade-off: more total ATP per second from fermenting most of the glucose, not less, despite each glycolysed glucose paying out far fewer ATP.
- Cancer cell / Normal cell — presets: cancer raises glycolytic Vmax (GLUT1/HK2/PFK upregulation) and the Warburg shift; normal keeps OXPHOS dominant.
- Warburg shift — the allocation control: how much of the glucose supply is routed toward glycolysis vs. oxidative phosphorylation before capacity limits and spillover are applied.
- Glycolytic / Oxidative capacity — each pathway's independent Vmax; try pushing glycolytic capacity far above oxidative capacity and watch the ATP-vs-shift curve invert.
- Glucose supply rate — total glucose entering per second; the crossover only appears once supply exceeds oxidative capacity, exactly as in a real, glucose-rich tumor microenvironment.
The live chart below sweeps the shift from 0% to 100% at the current capacities and supply, plotting total ATP/s — the genuine crossover point (if the curve's maximum sits away from 0%) is where glycolysis's rate advantage overtakes its yield disadvantage.