Most athletes still rely on heart rate to measure intensity. In steady-state endurance sports—like running, rowing, or cycling—that works. But in HYROX and functional conditioning , heart rate can be misleading. This idea was explained brilliantly by WOD Science  in one of their recent YouTube videos. Their research shows why heart-rate zones built for endurance sports break down once you add thrusters, burpees, sleds, and wall balls. Here’s what’s happening—and how we can us

1️⃣ What “Threshold” Actually Is Physiologically, threshold (LT2 / Critical Speed) marks the upper limit of sustainable effort  — the point where your body can no longer stabilise lactate and VO₂ drifts upward. Below threshold = steady-state aerobic metabolism . Above threshold = non-steady state  — lactate and fatigue rise continuously until you fail. For HYROX and running, this boundary defines your engine capacity : how hard you can go before the wheels fall off. Think of

Optimising VO₂max and Lactate Testing for Better Running and HYROX Performance Intervals are one of the most effective tools in endurance...