Ask most runners what a “VO₂max session” looks like and you’ll hear the same answer: fast reps, short recoveries, and a finish-line collapse. The problem? That approach rarely trains what people think it does. Modern research on endurance training paints a very different picture. Improving VO₂max isn’t about hitting your fastest repeat of the night — it’s about spending enough time  near your maximum oxygen uptake so your heart and lungs are forced to adapt. Why VO₂max still

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