Guides
In-depth guides on training zones, pacing, and race strategy — no fluff, no filler.
VDOT vs. Heart Rate Zones: Which Should You Train By?
Pace-based VDOT zones and heart-rate-based Karvonen zones measure different things. Here's when each one is more accurate, with a worked example.
Using the Riegel Formula to Predict Your Next Race Time (and When It's Wrong)
The Riegel formula is a solid starting estimate for a nearby race distance — and a poor one for predicting a marathon from a 5K. Here's the math and the limits.
Even Splits vs. Negative Splits: Which Marathon Pacing Strategy Should You Run?
Negative splitting is the textbook advice, but it isn't automatically right for every runner. Here's how to decide, with a worked pacing example.