Please note that this app is intentionally minimal in feature set to avoid forcing user to plan out detailed workouts with specific numbers of sets on different days. This app is meant to substitute for a clipboard, paper, pencil, and a stopwatch, nothing more.
It requires very few permissions, and doesn't use internet at all, so it works offline or in Airplane mode.
Logs are stored in a simple, readable JSON format, which can be synchronized across devices using something like DropSync/Dropbox. Logs are stored in /sdcard/SimpleHealthSuite/Strength/Logs, split by day.
This app is free and open source, code can be found at https://github.com/rodhilton/SimpleStrengthLog