Running · Physiology

Marathon Sweet Spot
Calculator

Computes your physiological sweet spot and achievable finish time based on VO₂max, lactate threshold, running economy, and training load.

Physiology
Age years
Sex
VO₂max ml/kg/min — estimate ok
48
30 · beginner 55 · trained 85 · elite
Training Profile
Weekly mileage km/week avg
Longest recent run km
Experience level
Personal Benchmarks
Recent 5K time mm:ss — leave 0 if unknown
Recent Half Marathon time hh:mm — leave 0 if unknown
Body & Conditions
Body weight kg
Race conditions
Injury/fatigue status
Nutrition Setup
Gel brand / type sets carbs per gel
Carbs per gel g — edit if custom
Stomach sensitivity
Caffeine gels mix in from km 25+
Analysis Output
● Sweet Spot Time
Optimal load — minimal damage, max adaptation
◆ Achievable Target
Realistic race finish with current fitness
▲ Overdoing It / Injury Risk
Pushing this pace risks overload, injury & long recovery
Per-Kilometre Paces
Sweet Spot Pace
min/km
Target Pace
min/km
Injury Risk Pace
min/km
Physiological Load Indicators
MetricValueAssessment
Est. Lactate Threshold Pace
% VO₂max at Sweet Spot
Estimated Glycogen Depletion Risk
Cardiac Drift Risk
Expected Recovery Time
Muscle Damage Marker Elevation
Overall Load at Sweet Spot
Recovery
Aerobic
Threshold
Hard
Maximal
Race Nutrition Plan
Race Nutrition Plan
Race Day Timeline
Hydration & Electrolytes
Pre-Race & Post-Race Protocol
© 2026 Andreas Katzer. Marathon Sweet Spot Calculator. Model based on Joyner (1991), Riegel fatigue factor, Billat cardiac drift, Bernat-Adell et al. (2021). Estimates are probabilistic — not a substitute for coaching or medical advice.