For most exercises Gym Hero is pretty good at guessing what muscle group they belong to, but if you use custom names that only very few people use, Gym Hero might not be able to guess. But no problem, you can go to
settings->exercise manager to quickly assign muscle groups to all of your exercises. Here’s a bunch of screenshots to help you:
On the start screen, tap the icon on the upper left corner:
Then open the exercise manager:
Then first tap the exercise you want to assign a muscle group to, then select the muscle group in the lower section of the screen:
If you think there’s any mistake in our crowd sourced muscle group assignments, let us know in the #support category!