The former Mr Universe's offspring Joseph Baena - who he has with his former housekeeper Mildred Baena - clinched first place in a number of categories at the NPC Natural Colorado State competition, including the Men's Open Body Heavy Weight Class, Men's Classic Physique True Novice and Men's Class Physique Novice, and also came second in Men's Classic Physique Open Class C.
Baena , 28, shared several photos from his bodybuilding debut on Instagram and wrote: "Mission Accomplished!"
Terminator star Schwarzenegger began his career as a bodybuilder and won the Mr Olympia title seven times and Mr Universe five times, before retiring from competition in 1980.
Baena hasn't always been in good shape and previously admitted he was dropped from his high school sports teams because he couldn't "keep up" with his peers.
"People sometimes forget that I used to be chubby in high school. I got cut from my basketball and soccer team because I couldn't keep up with the other kids," he wrote on Instagram in July.
"Swim didn't have tryouts thankfully and completely changed my life forever. That was my introduction to Fitness and training."
And Baena has previously told how he was bullied because of his weight when he was young.
"I was bullied when I was a kid, elementary, middle school, and not really in high school, but I just felt like an outsider in high school at the beginning," he told People magazine in 2022.
"I was really overweight from the end of elementary school into the beginning of high school.
"It was my closest friends that were the ones that bullied me the most and made fun of me for being overweight and all these kind of things.
"So, that was really a big struggle for me in finding myself and figuring out and creating that ambition to change my weight and my physique," he said.
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