Blog
heart rate articles
10 articles on heart rate, newest first. Every one is sourced and links to the calculator it applies to.
How Mark Allen Trained (and Why He Ran Slower to Get Faster)
Six-time Ironman World Champion Mark Allen capped his heart rate with Maffetone's 180-formula and watched his pace at that heart rate transform. A formula you can run now.
How Taylor Knibb Trains (and Why She Let the Leader Go in Kona)
Taylor Knibb won Kona 2026 in 8:36:29 a year after overheating 3 km from the line. The lesson: race your own limits, not the athlete beside you.
Zone 2 Heart Rate, Explained
What Zone 2 training is, why it builds your aerobic base, how to find your own Zone 2 heart rate with the talk test, LT1 or MAF, and how much of it to do.
What Heart Rate Zone Should You Train In?
Which heart-rate zone to train in and when: most time easy in Zone 2, a controlled dose at threshold, a little in Zone 5. Plus how to find your zones.
How to Set Your Training Zones (and Actually Use Them)
How to find your heart-rate, power and pace zones: pick the right anchor, test it with a field test, then train by it with a polarized week.
Finding Your Maximum Heart Rate
What max heart rate is, why the 220 minus age rule is shaky, and how to estimate or field-test yours. Includes a six-formula calculator.
Friel's Heart-Rate Zones: 5, 7, and Why Every Platform Numbers Them Differently
Joe Friel's LTHR zones explained: the 5-zone model, the 5a/5b/5c split that makes it 7, how intervals.icu renumbers them, and how to test your LTHR.
What a Training Zone Calculator Actually Does (and How to Use Yours)
A training zone calculator turns your max heart rate, threshold, FTP or race time into personal easy, tempo and hard ranges. Which input to use and how to act on it.
Heart Rate Reserve: Better Zones with the Karvonen Method
What heart rate reserve (HRR) is, the Karvonen formula that turns it into training zones, why it beats plain %HRmax, and how to measure the two inputs.
How Sturla Holm Lægreid Trains (Shooting Straight at 170 bpm)
Five medals in five races at the 2026 Olympics, none of them gold. Biathlon is decided by how fast your heart rate falls, and that is a trainable number.