About athletica.page
Athletica.page provides free, science-based running calculators and training tools. Every calculator on this site uses formulas validated by sports science research — no guesswork, no filler.
The Formulas
Race Time Predictor — Riegel Formula (1981)
The race time predictor uses the Riegel model: T₂ = T₁ × (D₂/D₁)^1.06. This formula was published by B. Riegel in Medicine and Science in Sports and Exercise and has been validated across distances from 5K to ultra-marathons. The fatigue exponent of 1.06 works well for most runners when predicting times within 2x the input distance.
Pace Calculator — Mathematical Conversion
The pace calculator uses direct mathematical conversion between pace, speed, and distance. 1 mile = 1.60934 km. Speed (mph) = 60 ÷ pace (min/mile). These are exact conversions with no estimation involved.
Training Zones — 80/20 Rule
Training zones are calculated using the 80/20 rule, the methodology described by Stephen Seiler in his research on elite endurance athletes. Zone 2 corresponds to 75-85% of race pace, while Zone 5 corresponds to 102-105% of race pace. This distribution optimizes performance while reducing injury risk.
Calorie Burn — MET Values
The calorie burn calculator uses MET (Metabolic Equivalent of Task) values from the Compendium of Physical Activities, maintained by the University of South Carolina. Running at various speeds has MET values ranging from 8.3 (5 mph) to 23.0 (14 mph). Calories = MET × weight (kg) × duration (hours).
Limitations
These calculators provide estimates based on mathematical models. Real-world performance depends on many factors including terrain, weather, altitude, fatigue, nutrition, and training history. Use the results as guidelines, not guarantees.
Contact
Questions or suggestions? Get in touch.