Your smartwatch and home devices track more than steps. These guides explain heart rate, blood oxygen, sleep stages, HRV and the rest — what’s normal, and when a number actually matters.
If your fitness watch nudges you about “Zone 2” or splits your workout into coloured heart rate zones, it’s using a simple but powerful idea: the harder you work, the faster your heart beats, and different heart rates train your body in different ways. Heart rate zones turn that relationship into five bands of intensity,…
If your sleep tracker breaks your night into sleep stages — light, deep, and REM — it’s showing you something your body has been doing all along: cycling through distinct phases that each do a different job. Far from being a single “off” switch, sleep is an active, structured process, and understanding these stages explains…
If your smartwatch shows a VO2 max number, comparing your VO2 max by age is the quickest way to tell whether it’s good, average, or worth working on. VO2 max is the maximum amount of oxygen your body can use during all-out exercise, and it’s widely considered the single best measure of cardiorespiratory fitness —…
Heart rate variability (HRV) is one of the most interesting numbers on your smartwatch — and one of the most misunderstood. Unlike most health metrics, with HRV a higher number is usually better, not worse. So what exactly is heart rate variability, what counts as a good score, and how can you improve yours? Let’s…
If your smartwatch or a fingertip device has ever flashed a number like “98%” at you, that’s your blood oxygen level — and it’s a quick window into how well your body is being supplied with oxygen. But what counts as a normal SpO2 reading, when is it too low, and how much should you…
Blood pressure is one of the most important numbers your body produces — yet most people have no idea whether their reading is healthy. It quietly shapes your risk of heart attack, stroke, and kidney disease, often without a single symptom. So what is a normal blood pressure by age, what do the two numbers…
Your resting heart rate is one of the simplest — and most revealing — numbers your body gives you. With a finger on your wrist or a glance at your smartwatch, you get an instant clue about how hard your heart is working and how fit you are. But what counts as a normal resting…