Meet the LifeTrak Zoom HRV: a wrist-worn device with automated HRV that accurately tells you how fit and recovered you are. It measures heart rate data from various parts of your body and monitors physical fatigue. It also works for swimmers. When worn on the ankle, the device can measure cadence for cyclists.
Zoom HRV also has sleep analysis. It syncs the data to an app to help you make sense of the data. Thanks to this wearable device, you can determine how hard to push yourself.