Continuing education - what are the best online courses you’ve taken outside of the standard certifications?

I’m a newer trainer and am looking for continuing education courses online. I did my CPT through NASM and am currently finishing my CES through them as well. I’m interested in moving more into corrective biomechanics work and am looking for courses to take (as well as free online resources) in biomechanics and corrective exercise. Note, they don’t need to be for CEU for NASM, just for educational purposes.

I’m also interested in other non-corrective focused courses that may have been helpful for you in expanding your programming and exercise banks. For example, I’m looking into kettlebell coach courses.

Let me know what courses and certifications you found helpful! Thanks y’all