Running BrowserEffort
Pace relative to your lactate threshold, easy and quality distance, and how they combine into the Effort of a run.
Science & methodology
Running Science
This application uses two key metrics to quantify training load: Effort and Fatigue. These metrics help runners understand the intensity of individual workouts and the cumulative fatigue from recent training.
Science articles
Environmental Adjustments
How wind, hills, terrain and weather change Effort, and why the ideal-pace model counts them differently.
Training fatigue
How distance and Effort build into a 21-day training load, with decay, rest days and worked examples.
Planning a training block
From current fitness to a training block: phases, weekly volume, long runs, key sessions and tapering.
Fitness scores and ideal conditions
Pace in ideal conditions, aerobic, interval and tempo scores, and what the trends can and cannot show.
Model reference
Default settings and constants
Default settings and fixed constants, read directly from the calculation code.
Glossary
The terms used in the models, from lactate threshold to training phases and fitness scores.
Scientific References
The scientific sources cited in these articles, with stable links from every citation.
How to read these models
Principles
- Personal. Effort is anchored on your own threshold pace, plans on your own volume and training days, fitness on your own earlier weeks. Nothing compares you with other runners.
- Transparent. Every number can be traced: tap Effort or Fatigue in the app to see its calculation, and these articles explain the rest.
- Conservative. Where the evidence is uncertain the models lean cautious: load is counted generously, fitness is credited sparingly, and plans grow slowly.
- Live. The figures and tables in these articles are computed as you read, by the same functions that run your log.
Notation
- Paces are minutes and seconds per kilometre (4:20/km); a difference in pace is in seconds per kilometre.
- E is Effort, F is Fatigue and T the threshold pace. Distances are in kilometres unless marked m.
- Numbers are rounded the way the app shows them, so a calculation by hand may differ in the last digit.
Every model in these articles is a simplification. They are meant to make training easier to read and to plan, not to replace how a run felt, or the advice of a coach or a doctor.
These articles describe a training model. It is not medical advice: check with a doctor before you start or change a training plan.
Try the calculations
Running Browser
Use the models in your own training
Plan and log your runs in Running Browser. Try it without an account; register to save your training across devices and connect Strava.