Complex sentence: A martial arts champion with experience in gymnastics and swordfighting, Park was originally only a member of the stunt crew, and stunt coordinator Nick Gillard filmed Park to demonstrate how he envisioned the lightsaber battles.
Split into simpler sentences: A martial arts champion with experience in gymnastics and swordfighting, Park was originally a member of the stunt crew. Stunt coordinator Nick Gillard filmed Park to demonstrate his conception of the lightsaber battles.