If they want true anonymity, then remove at least location part of this (or say with 50km precision). Make it all optional with clear description what user opt for. And have independent yearly audit that confirms this on their core databases.
Anything less that that, and their motives are dirty as stale sewage waters. Why it seems that every company out there is only after as-much-data-as-possible from our lives, ideally all lives on the planet, to somehow monetize them in future? And ideally get bought by some big corp for few billions for owners.
Yet another useless thing I am happy to pass (and I am fitness nerd, but never saw any appeal in these measuring devices - work out hard, have fun, keep doing it often and you will be exceptionally healthy)