The former Malcom in the Middle star revealed on the Sept. 18 premiere of DWTS that he had broken his back in a 2009 car racing accident.
“I don’t really ever feel my back [in my everyday life] because I don’t do anything like this,” Muniz, 31, told PEOPLE after Monday’s episode of DWTS. “My lower back, it scares me because I’m trying to protect it when I dance and that makes me tense up, which isn’t good.”
Muniz admits that just two days before dancing to rave reviews on Monday’s ballroom night, he was “messed up” to the point that he couldn’t move.
“I was stuck,” he told reporters. “We’ve been having to end practice early, which sucks in a week that you have to learn two dances. My mind says I have to keep going but I physically can’t. I try to do it one more time but I say, ‘Okay, now I’m going to cause more damage.'”
Muniz’s pro dancer partner Witney Carson verifies his dangerous work ethic.
“In rehearsal I’ll say, ‘Okay, we have to stop,'” she said. “And Frankie is like, ‘No. No. We have to keep going.’ And I’m like, ‘No. We have to stop. It’s to that point.'”
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Muniz says he’s been doing yoga, physical therapy and cryotherapy constantly to help combat his pain.
“As soon as I’m done with rehearsal, my entire day is healing,” said the actor, who had never done cryotherapy before DWTS but has been doing going up to twice a day over the past week.
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But he also admitted that after Monday’s show, “it hurts really bad right now, probably the worst it’s felt all week.”
But he says nothing will keep him from performing on Tuesday’s show.
“I would be more disappointed than anything if I couldn’t dance because of [my injuries.] I’d rather dance and get 1s and get sent home than not be able to dance at all,” he says. “I love being a part of it and I love dancing and I don’t want to go home any time soon because I just want to keep learning and dancing.”
Dancing with the Stars‘ special Latin Night episode airs Tuesday at 9 p.m. ET on ABC.