A VO₂ Max test measures maximum oxygen uptake, revealing heart–lung efficiency, aerobic capacity, personalized fat-burning zones, and performance benchmarks providing the most accurate assessment of endurance fitness. Higher VO₂ Max means a stronger heart, denser capillaries, richer mitochondrial machinery, and superior endurance. It predicts race performance, all cause mortality, and cardiovascular risk better than almost any other single fitness metric. It is the north star for aerobic performance and long term health.
Zone 2 represents a moderate-intensity training zone where your body primarily uses fat as its main fuel source while maintaining a steady aerobic state. It sits just below the first lactate threshold intense enough to challenge the heart, yet sustainable for long durations without heavy fatigue. It occurs at roughly 60–75% of your maximum heart rate, or 65–75% of VO₂ Max. At this level, your mitochondria are fully engaged in aerobic metabolism, efficiently burning fat and oxygen to produce energy with minimal lactate buildup.
