calculate YOUr HEART RATE ZONES
First, find your 2nd Lactate Threshold: The 30-Minute Time Trial
Your training zones are only as good as the number you anchor them to. This test gives you that individual physiologic anchor: a field estimate of your second lactate threshold (LT2)—the intensity where lactate starts accumulating faster than you can clear it. It's the most meaningful single marker for setting endurance zones, and you can find it with nothing but a watch and a hard 30 minutes.
Here's exactly how to do it.
Before you start
Pick a day you're rested—not the day after a hard session. Treat this like a race effort, because that's what it is.
You'll need a heart rate monitor (a chest strap is more reliable than a wrist sensor for this), and a way to measure pace, power, or speed depending on your sport. Warm up for 10–15 minutes, building from easy to moderate, with two or three short surges near the end to open things up.
Choose a setting where you can hold a hard, uninterrupted effort: a track, a flat road or path, a treadmill, an indoor trainer, or an erg. Stops and sharp turns will distort the result.
The test
Go hard for 30 minutes. The goal is the highest effort you can hold steady for the full duration—not a sprint you fade out of, and not a pace you finish with a lot left in the tank.
The most common mistake is starting too fast. Settle into an effort that feels "comfortably hard" for the first few minutes, then hold or build slightly. If you're crawling in the last five minutes, you went out too hot—note that for next time, but finish anyway.
Record the entire 30 minutes, then pull the averages your sport needs:
Running: average heart rate and average pace over the final 20 minutes.
Cycling: average heart rate and average power over the full 30 minutes.
Rowing / other: average heart rate and average power, pace, or speed over the full 30 minutes.
Get your zones
Once you have your numbers, the calculator does the math—translating your threshold into full heart rate and power/pace zones for your training.
A field test gets you close. If you want lab-grade precision—your actual lactate curve, VO2max, or the specific limiter holding your endurance back—that's what metabolic testing is for.
