Methodology

How these calculators work and what they're based on.

Philosophy

LongRunLogic is built on four principles:

  • Use ranges, not absolutes. Running is individual. A 15-mile long run might be perfect for one runner and excessive for another. We always provide ranges to account for this variability.
  • Scale stress to workload. Training stress should be proportional to your current fitness and volume. As you build, the nature of your training can evolve.
  • Emphasize sustainability. The best training is training you can do consistently, week after week, without breakdown.
  • Avoid rigid rules. Guidelines like "never run more than X miles" or "always fuel after Y minutes" often ignore context. We provide frameworks for thinking, not commands to follow.

What These Calculators Are

These tools are decision-support calculators. They help you think through common training questions by applying widely accepted distance-running principles to your specific inputs.

The recommendations are based on:

  • Established training literature and coaching practice
  • Commonly used guidelines (e.g., long run as percentage of weekly volume)
  • Physiological principles around fueling and hydration
  • Recognition of diminishing returns and injury risk patterns

What These Calculators Are Not

  • Not training plans. These tools don't prescribe workouts, periodization, or progressive overload schemes.
  • Not coaching advice. A coach considers your full context-injury history, goals, life stress, sleep, and more. These calculators can't do that.
  • Not medical guidance. If you have health concerns, injuries, or specific conditions, consult a healthcare professional.

Calculator-Specific Notes

Long Run Calculator

Long run recommendations are based on the common guideline that long runs typically represent 20–30% of weekly mileage, with the percentage decreasing as total volume increases. Time caps are applied for each race distance to reflect the point of diminishing returns where fatigue costs begin to outweigh fitness benefits.

Fueling Calculator

Fueling recommendations follow sports nutrition consensus: carbohydrate needs increase with duration, fluid needs scale with conditions, and sodium replacement becomes relevant for efforts exceeding two hours. Body weight refinement uses the 0.6–0.9 g/kg/hour guideline as an intersection with duration-based ranges.

Weekly Mileage Sweet Spot

Base ranges reflect commonly cited training volumes for each race distance. Adjustments for experience and age acknowledge that newer runners may benefit from conservative building while experienced runners can often tolerate higher volumes. The durability check flags when long run concentration is disproportionately high relative to total volume.

Sources and Influences

These calculators draw on principles found in widely used training resources, including:

  • Jack Daniels' Running Formula
  • Pfitzinger & Douglas, Advanced Marathoning
  • Matt Fitzgerald, 80/20 Running
  • ACSM position stands on fluid replacement
  • Asker Jeukendrup's carbohydrate research

No specific source is cited for any single number because these calculators synthesize general principles rather than reproduce specific protocols.

Feedback

If you notice an error, have questions about methodology, or want to suggest improvements, reach out via the contact information on the About page.