What is an activity minute on TensRelief?

If the movements pass a certain threshold within a minute, this is counted as an 'activity minute'. The threshold is programmed in such a way that any kind of movement is registered: strolling, running, exercising or doing household activities, as long as the waist is in motion.
An activity minute does not identify how intense the activity has been; there is no distinction between slow running, fast running, walking or climbing the stairs.