Ryan Destiny took naps between takes while filming boxing matches for The Fire Inside

Ryan Destiny took quick power naps whenever she could while filming the intense Olympic boxing matches for The Fire Inside.

In the biographical sports drama, Destiny portrays Claressa Shields, who became the first American woman to win Olympic gold in boxing in 2012.

All of the Olympic matches were filmed over six consecutive days and Destiny was so physically exhausted from the constant fighting that she took a nap whenever she got the chance.

"There's so many shots that they have of me sleeping," she shared in an interview with Cover Media. "I'm like sleeping at any time that I could fit in a five-minute nap. It would be me sleeping in the ring, sleeping on the side, I would take any moment that I could to sleep."

Laughing alongside her star, director Rachel Morrison recalled, "You'd say cut and she'd slump over and take a quick nap until we were ready with the next (camera) setup. It's like, 'Who's gonna wake Ryan this time?'"

Destiny, 30, added that she "really appreciated" Morrison and the crew letting her rest before fighting some more.

"I'm really glad that I had those moments. But yeah, it was a lot. But it was nice to be able to say that I could go back-to-back take after take because it was very necessary," she said.

When asked if she felt nervous playing one of the greatest female boxers of all time in front of a huge crowd, the singer explained that she treated her boxing ring sequences like a stage performance.

"It was kind of exhilarating and exciting for me. It was almost like stepping on stage to perform and that's just a different, new type of feeling of adrenaline that kicks in and you just kind of live for it and love it. It's nice when you feel confident in what you're doing," she noted. "So I think I was more excited all the time than scared."

The Fire Inside will be released in U.K. and Irish cinemas on 7 February.