Research
Every measure in our scoring system traces back to peer-reviewed research. Below are the 68 claims, anchored to 293 studies. Click any claim to see the studies behind it, the strength of the evidence, and the plans that respect it.
Adapting
- Your heart rate drops at the same pace High
- Blood and tiny vessels change first Medium
- Bone is slow to catch up Medium
- Bone needs impact and fuel, not just miles Medium
- The body adapts on a staggered clock Medium
- Your aerobic engine builds over weeks Medium
- Trained runners may gain durability more than VO2max Low
Biomechanics
Equipment
Heart
- Fitness and age shape your resting heart rate High
- Heart-rate zones guide how hard you train High
- Higher VO2 max goes with a longer life High
- You can estimate VO2 max without an all-out test High
- A lower resting heart rate goes with lower health risk Medium
- Heart rate is a weak calorie signal near rest Medium
- Running lifts mood Medium
- Training raises VO2 max, but how much varies widely Medium
Injury
Intensity
- Build training zones around effort, not age High
- Easy miles do most of the work High
- Polarized training matches or beats threshold-heavy plans High
- Explosive work can make you more efficient Medium
- Keep easy days easy, hard days hard Medium
- Mix easy and hard instead of steady medium Medium
- Short hard intervals work when time is tight Medium
Mileage
Nutrition
- Fat loss depends on the energy deficit High
- Formulas estimate resting calorie burn within about 10% for most adults High
- Fuel your training or the gains stall High
- More protein protects muscle during weight change High
- Digesting food burns calories, protein most Medium
- Healthy eating fits a wide macro range Medium
- Keep carbs high enough to fuel hard days while cutting Medium
- Lose weight slowly to keep muscle Medium
- MET estimates improve when scaled to you Medium
- A small calorie surplus builds muscle with less fat Low
Performance
- Individualized plans beat one-size-fits-all High
- Recreational marathon pace sits below threshold High
- 5K and 10K race pace sits near threshold Medium
- Resilience is the fourth performance factor Medium
- Three factors behind race speed Medium
- Your training data can predict a race time Medium
- A half marathon first may help new marathoners Low
Race Preparation
Strength
- Strength training keeps muscle while you cut High
- Strength training lowers injury risk High
- Strength training makes running more efficient High
- Two strength sessions a week is enough High
- Foot-strength work lowers injury risk Medium
- Guided strength work has the better record Medium
- Heavy lifting improves running economy Medium
- You can keep strength while cutting Medium
- Don't lift heavy right before a key run Low
Other
The corpus is versioned and re-checked. See how we score.