Disclosed systems and methods relate to determining an intensity level of an exercise using a photoplethysmogram (PPG) sensor. A method of determining an intensity level of an exercise for a user according to one embodiment of the present disclosure includes detecting, by a device, body signals from the user using a PPG sensor. The method includes determining, by the device, a heart rate of the user based on the body signals. The method includes determining, by the device, an error in the heart rate. The method also includes determining, by the device, the intensity level of the exercise for the user based at least on the error.
Systems and methods for determining an intensity level of an exercise using photoplethysmogram (PPG)