10 year old crying for thirty minutes straight over going to martial arts practice

He’s been going for over 2 years. Lately he doesn’t want to go on Wednesdays because that’s sparring day. Yet, when I pick him up he’s smiling big and always glad he went. The environment is controlled with all the safety gear. Once in a while he’ll get the wind knocked out of him. He leads the warm ups and is well liked. He just seems to be scared of something that he’s already done dozens of times. The coach can be firm, but I’ve also seen him show a great deal of love and empathy. Just want him to calm down and walk in. Allowing him to cry and validate his fear. Not sure what else to do.