the short answer
Online fitness coaching is a remote coaching service where a coach designs a client's training and nutrition, delivers it through a coaching app, and guides the client with a structured weekly check-in and ongoing messaging instead of in-person sessions. From the coach's side it is a repeatable system - remote programming, app delivery and check-in review - that lets one coach support far more clients than face-to-face training ever allows.
The rest of this page unpacks that definition: what an online coach delivers each week, how the delivery loop actually runs, and what it costs to run on both sides.