How can I display a grid composed of different fields on a form? Is there a way to do so?

To do this natively on the form, put each ___ as a field like bench_set, bench_rep, etc. Then put those on the same line in the form elements page. 

I've built a gym management app, as part of it we create and manage the workout programs.

This is actually the app that we won the 2017 App-a-thon with at Empower.



This is only a fraction of what it does.  But should give you some ideas.

Are you looking for analytics on the types of movements they are performing, frequency, etc.  Or on the weight used?  Every sessions weight, or just the max used in the cycle?

How you construct it depends on how you want to use it, and how you might want the end user to interact with it.  I've done a few different versions for different needs.