See the 'What should I avoid while wearing my Apple Watch?' section in:
About Apple Watch water resistance - Apple Support
You should avoid dropping Apple Watch or subjecting it to other impacts
If your Apple Watch comes in contact accidentally with soaps, shampoos, conditioners, lotions, perfumes, solvents, detergent, acids or acidic foods, insect repellent, sunscreen, oil, hair dye, or any substance other than water, it should be cleaned with fresh warm water and dried with a lint-free cloth. Chemicals found in these items could negatively affect water seals and acoustic membranes.
I have heard that some people wear their watch on their ankle while riding a bicycle. That might avoid volleyball impacts in your case, but I doubt the watch will still monitor your heart rate accurately.