Heart Rate Monitor - HeartIn

HeartIn measures your pulse through the phone camera and, more unusually for an app of this kind, tracks heart rate variability. HRV is worth explaining because most people have not met it. It is not how fast your heart beats but how much the interval between beats varies, and counterintuitively more variation is generally better. A heart that adjusts constantly is responding well to what your body needs; one beating like a metronome usually indicates strain, poor recovery or stress. Athletes use HRV to decide whether to train hard or rest, and it responds to sleep, alcohol, illness and workload before you consciously notice any of them. Measured over weeks, a downward trend is a genuine signal worth attending to. Pulse checks take seconds: a fingertip over the camera and flash gives a reading before or after exercise, at rest, or whenever you are curious. A blood pressure log holds readings taken with a proper cuff, since no phone can measure blood pressure itself. Everything collects into one wellness record with trends over time, which is where the value lies, because single measurements of any of these say very little. It is not a medical device. Pulse and HRV are only meaningful measured under consistent conditions, ideally in the morning on waking, before coffee and before exertion. A single reading at a random point in the day tells you almost nothing.