A running partner app could match people by preferred distance, pace, time and approximate area. Someone seeking a relaxed morning run may need different suggestions from a runner preparing for a timed event.
Privacy should influence the design from the beginning. Public profiles need not reveal home addresses, regular routes or live location. Users could agree a public meeting place after accepting an invitation, with controls for blocking and reporting unwanted contact.
Start with organised groups or a defined local area to avoid an empty directory. Test how users describe pace and how they change plans when conditions alter. A clear confirmed plan is more useful than a stream of vague nearby matches, especially when people are meeting for the first time.
Related reading: Membership and Club Management Software.