With our current offering, workouts must be manually started in the Biostrap app for the exercises to be detected.
Our devices have gyro and accelerometer. To save battery, we don't always have gyro running. And normally, the accelerometer scans at 10Hz all day long to capture casual/trivial steps.
But, when user clicks START button to start an activity/workout, we start Gyro and increase the scanning frequency on the accelerometer, which we need to increase accuracy of our classification.