Gyms are bad places for a network. Basements, thick walls, and a room full of phones on the same Wi‑Fi mean a tracker that waits on a server will stall between sets. The set still happened. The log should not depend on whether the request got out.
An offline workout tracker writes the session on the device first. Sets, reps, and weight stay on the phone while you train. When the phone has a connection again, that session syncs. You do not re-enter it in the parking lot.
That only works if the logging itself is small. You are not browsing a program library between sets. You are recording the work in front of you. The Android gym log is that record: the exercise, the sets, the reps, the weight.
The plan for the session can still be specific. Pact checks that a workout covers the muscle groups and movement patterns you train, instead of shuffling a template. That is covered in why a workout plan should cover muscle groups. The check happens so the session is ready when you walk in, including when the network is not.
Pact keeps core workout flows on the device. The app is Pact, on Android.