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Glossary · Sweat Rate · Sodium Concentration · Carbohydrate Intake · Mechanical Work
The protocol Veloarchitect uses for carb and electrolyte timing around indoor sessions. Indoor sweat rates exceed outdoor at matched intensity; the protocol reads longitudinal sweat-rate data and dispatches the per-hour target.
Definition
Fueling Window is the protocol that owns the Athlete's peri-session nutrition — carb intake, electrolyte replacement, hydration timing. The protocol is structurally indoor-specific: indoor sweat rates can exceed outdoor at matched intensity because the body has no evaporative cooling pathway over a stationary bike. Veloarchitect reads the Athlete's longitudinal sweat-rate data (sodium concentration, fluid loss per hour) and dispatches per-hour targets calibrated to the Athlete's physiology, not a population default. An Athlete targeting a 5-hour gran fondo receives a 90g/hr carb target if their longitudinal record supports it; an Athlete targeting a 60-minute criterium receives a 30g/hr target. The Athlete who treats fueling as "60g/hr always" overrides the protocol's longitudinal calibration.
Protocols: Protocol 1 — Zone Endurance; Protocol 10 — Adaptive Workout
Closed Loop
The metric traverses the closed loop: Intent is the .zwo prescription the system computed against the Athlete’s True Normal. Telemetry is the .fit recording of the executed session. Adaptation is the longitudinal movement of the metric itself, logged against the True Normal and feeding back into the next day’s prescription via Protocol 10 (Adaptive Workout).
Worked Example
Athlete preparing for a 130 km gran fondo. Week 0 longitudinal sweat-rate read: 1.6 L/hr, sodium concentration 1,200 mg/L. Standard fueling recipe suggests 60g/hr carbs + 700 mg/hr sodium. Veloarchitect calculates by sweat-rate: 84g/hr carbs (matching 1.6 L/hr fluid loss at 6% carb solution) + 1,900 mg/hr sodium (matching 1,200 mg/L concentration × 1.6 L/hr). Athlete tests the calibrated target across 4 weeks of indoor 3-hour Z2 sessions. Mechanical Efficiency holds at 1.62 W/bpm across the 3-hour window (no degradation from under-fueling). Race-day fueling Execution Precision: 0.94.
Common assumption inverted
Fueling Window is not "60g/hr carbs always" or "drink to thirst." Both are population defaults; the Athlete who follows them ignores their longitudinal sweat-rate record. Veloarchitect reads the Athlete's sodium concentration, fluid loss per hour, and Adaptation Rate to derive per-hour targets. The Athlete who treats fueling as a fixed recipe will under-fuel on hot days (degradation shows on Mechanical Efficiency by hour 3) and over-fuel on cool days (gastrointestinal distress logs a 1/5 severity in the Discomfort Log). The protocol calibrates to the Athlete; the Athlete does not negotiate the calibration.
Related Terms
Zone Endurance (Protocol 1) — Zone Endurance
Mechanical Efficiency — Mechanical Efficiency
Adaptation Rate — Adaptation Rate
Full Glossary
See all eleven proprietary metrics or the platform comparison for the closed-loop claims against the field.