WHAT: Please add HRV data to to the app and record sync in Apple Health. It can be easily computed from the time series of HR you already recording in the app.

WHY: It is a highly valuable and informative metric. HRV helps apnea and diving trainees by signaling stress and recovery status, guiding daily training intensity, indicating heart's adaptability for longer breath-holds, flagging fatigue risks, and tracking improvements in cardiorespiratory function. It also monitors mental and physical resilience.