WP_Query return highest number only

by

If I get this right each of your posts have one value of Exercise and one Value of Tempo?

I would do the following probably:

  1. Build a list of exercises.
  2. For each exercise query query: 1 posts, ordered by Tempo, descending.

This is probably as good as it gets staying within realm of WP API. Might not be practical for high counts of Exercises, it’s all custom SQL from there.