It souds cool and possible to work but I want to remind you that people happily used fake gps apps in even pokemon go to show themselves walking/running. Getting rewards. How can this app block this especially on android, I don't know.
So.. rewards will only be given out if you are training with a personal trainer; and you have already bought that service on the Lympo platform or from their partners. For example, everyone who runs in the Vilnius marathon this September will be eligible. If open challenges are organized, they plan to add various max limits and other rules to minimize the risk of cheating.