Updating my original 4 star review because developer added 2 requested features: longer recording time and audio continues to run in the background. This made using this app for voice guidance while weightlifting even better. I use the repeat slider to determine the number of sets.
It would be useful to be able to import audio files edited elsewhere, or to assemble short clips inside the app. My workaround is to record “Rep 1…Ready…Begin…Contract…Hold…Extend…Rest…10,9,8,7,6,5,4,3,2,1… Rep 1…Ready…Begin…Contract… and so on. It took several takes for 12 reps but now my timing is consistent and I know how many reps remain.
Apple Voice Control can start each group of sets; refer to Apple documentation of this Accessibility feature for details. Wearing AirPods, I say “Press 1” to start each new exercise, and to stop at anytime.