From the training log
Running, Explained
The math and physiology behind the calculators — written by a runner, for runners.
Race Prediction
- How the Riegel Formula Predicts Your Race Times
The 1977 equation behind nearly every race predictor — and where it breaks down.
- Predicting Your Marathon From a Half: Two Models, Two Different Answers
Why the Riegel prediction and the classic doubling rule rarely agree.
- Yasso 800s: Bart Yasso's Marathon Predictor, Explained
How the Yasso 800s workout predicts marathon time, and its real limitations.
Pace, Speed & Splits
- Pace vs. Speed: What Runners Actually Need to Know
Why runners think in minutes per mile, and the mental math that makes racing easier.
- Treadmill Pace Conversion: What Your Belt Speed Means on the Road
Why treadmill pace and road pace aren't the same effort.
- Turning a Goal Pace Into Track Lap Splits
The math between your goal pace and the numbers on the track clock.
- Negative Splits: Why the Best Marathoners Run the Second Half Faster
The pacing pattern behind nearly every fast marathon.
- The Galloway Run-Walk Method: When Walking Makes You Faster
Planned walk breaks often beat running straight through.
Training
- The Five Heart Rate Training Zones, Explained
What each zone trains, and why most easy runs are too fast.
- What VO2 Max Really Means for Runners
The most quoted number in endurance sport — what it does and doesn't tell you.
- The 10% Rule for Weekly Mileage: Useful Guideline or Myth?
What the rule gets right and where it fails.
- Cadence and Stride Length: Is 180 Steps a Minute Actually Magic?
The most repeated number in running form advice.
Fitness & Body
- BMI for Runners: Why It's the Wrong Number for Most of Us
A population statistic never built to measure muscular athletes.
- How Body Weight Actually Affects Race Pace
A widely cited heuristic for how weight change shows up on race day.
Fuel & Hydration
- Carb Fueling for Long Runs: How Much, How Often, and Why Your Stomach Fights You
Races over 90 minutes are fueling problems as much as fitness problems.
- Sweat Rate: The One Number Every Hydration Plan Should Start With
Generic hydration advice is built for an average sweater.
Course & Conditions
- Running in the Heat: Why You Need to Slow Down, and By How Much
Warm air taxes cooling before it taxes muscles.
- Racing at Altitude: What Actually Happens to Your Pace
Thinner air doesn't care about your training log.
- Grade-Adjusted Pace: Why Hills Aren't Symmetrical
A downhill mile doesn't refund what the uphill mile cost you.
- The Naismith Rule and Elevation Gain: Translating Climbing Into Flat Miles
Still doing useful work on race courses today.
More articles are added as the site grows. If there's a running question you'd like broken down by the numbers, send it in — or head back to the full calculator library.