Apple Watch’s New VO2 Max Test: How It Measures Your Cardiorespiratory Fitness

Your Apple Watch can tell you how fast you're moving, how your heart responds to exercise, and how your workout changes over time. But one of its more interesting fitness metrics is something it can't directly measure: VO2 max. VO2 max represents the maximum amount of oxygen your body can use during intense exercise. It's widely used to assess...