Mosier, who began questioning his gender identity when he was four years old, said he finally feels comfortable in his own skin

The magazine selects a few athletes each year for a series of naked photos

Now Mosier, who competes in the run-bike-run race, will appear in ESPN's Body Issue in July

Chris Mosier, 35, became the first transgender athlete to join a national team in the United States last year

A duathlete who became the first transgender person to join a national team in the United States has broken another barrier by gracing the pages of ESPN's Body Issue.

Chris Mosier, 35, who competes in the run-bike-run race, is the first transgender athlete to make it in the magazine, which features a selection of athletes in a series of naked photos every year.

He qualified for Team USA last year and has since pushed for the International Olympic Committee to make its policy more inclusive of transgender competitors.

'For 29 years, I didn't want to have my photo taken because what I saw reflected back did not match how I saw myself and how I felt inside,' Mosier, who began transitioning from female to male in 2010, said on Facebook.

Chris Mosier (pictured), 35, who competes in the run-bike-run duathlon, has become the first transgender athlete to appear in ESPN's Body Issue

Mosier (pictured) qualified for Team USA last year and has since pushed for the International Olympic Committee to make its policy more inclusive of transgender competitors

'I am so proud to be where I am now -and to be in the 2016 Body Issue (OMG!!) alongside Dwayne Wade, Von Miller, Greg Luganis and more.'

Mosier began to question his gender identity when he was four years old. Ultimately, his wife Zhen encouraged him to begin therapy, CNN reported earlier this year.

He said the experience had made him 'a better athlete, a better person and a better husband'.

'Even two years ago, I wouldn't have imagined I would have the courage or desire to do the Body Issue,' Mosier told the Huffington Post on Tuesday.

'But I'm more and more comfortable and confident every day, and I finally feel at home in my body

'I love my body. It took a long time for me to get to a point where I could say that, so I'm happy to be in a place where I can share that with the world.'

Appearing in the Body Issue was a way for Mosier (pictured earlier this year) to share his love for his own body with the world after 29 years of not wanting to have his photo taken, he said

This will be the eight annual edition of ESPN's Body Issue, which senior deputy editor and producer Neely Lohmann called a 'powerful storytelling platform'.

'Year after year, the athletes allow themselves to be completely vulnerable with our audience—not just in the photographs but with their interviews as well,' Lohmann said in a release.

'This year we have athletes opening up in raw and moving ways about overcoming physical struggles: everything from asthma to HIV, amputation to transgender transitioning. It's an honor to tell their stories.'

This year's Body Issue, which also features MMA star Conor McGregor, MVP Elena Delle Donne and the Pittsburgh Steelers' Antonio Brown, will become available online on July 6 and will hit the newsstands on July 8.