it can be used to extend your profile based on exactly those. then that profile can be used to sell you sports equipment and drugs (in the pharmacy sense).
the information about when and where do you work out can also be used to learn other things, employment status and schedule, how often it varies, when you are on holiday or sick leave. who you may have met while exercising. if you pay for a gym and how expensive that place is that you were willing to pay. who knows what else.
Like on a meta level maybe, but why do you think China or anyone else cares about something like your heart rate or workout habits?
it can be used to extend your profile based on exactly those. then that profile can be used to sell you sports equipment and drugs (in the pharmacy sense).
the information about when and where do you work out can also be used to learn other things, employment status and schedule, how often it varies, when you are on holiday or sick leave. who you may have met while exercising. if you pay for a gym and how expensive that place is that you were willing to pay. who knows what else.