What started as routine training for the young Australian athlete took a devastating turn, leading to an unexpected medical crisis that doctors could not reverse.

A 21-year-old Melbourne man has died after suffering from a severe case of rhabdomyolysis, a condition linked to high-intensity exercise. Jake Sendler, an amateur MMA fighter and personal trainer, had been unaware of the condition until it progressed to a life-threatening stage, leading to his hospitalization.

Jake was rushed to the hospital after experiencing symptoms that did not initially seem alarming. He was placed in intensive care, where doctors informed his family that his chances of survival were slim.

Despite undergoing multiple surgeries and spending days in an induced coma, he passed away on March 13, 2025 — less than two weeks after being hospitalized.

“When we got into the ICU, the doctor said when they opened him up again (in another emergency surgery) there was just too much tissue that had died and there was so much damage, there was nothing more they could do,” his mother, Sharone Sendler, told news.com.au. “I said to him, ‘it’s OK baby, you can rest now, you fought so hard’ and I kissed him on the forehead and he passed away. It was the worst moment of my life.”

Sharone is now advocating for awareness about rhabdomyolysis, which she calls a “silent killer,” hoping to prevent other families from experiencing the same loss.

Rhabdomyolysis, often referred to as “rhabdo,” occurs when muscle tissue breaks down and releases toxins into the bloodstream, potentially leading to kidney failure and complications with the heart and other organs. Symptoms include muscle pain, fatigue, and dark urine.

For Jake, muscle soreness was a common part of his rigorous training routine, and he initially dismissed the warning signs. After noticing tea-colored urine, he increased his fluid intake, assuming dehydration was the cause. He was known for being “extremely healthy” and maintaining a strict diet of organic foods.

A day before his scheduled fight on March 2, Jake appeared confident and full of energy. In a video recorded at the time, he shared his excitement. “Feeling really good, excited, pumped,” he said.

Cleared by medical professionals to compete, Jake stepped into the ring at the Melbourne Pavilion, unaware that his body was already in distress. The match, which lasted the full three rounds, was meant to be another step toward his dream of becoming a professional MMA fighter.

“He sold 60 tickets to family and friends to come watch him,” his mom shared. She added that he had no idea his organs had already begun to fail.

Despite struggling, Jake refused to give up. “Right up until the end he put his hands up to show the refs he is not out, so he made it through the full three rounds and was helped to walk out of the ring,” Sharone recalled.

After the fight, he experienced severe pain and difficulty breathing. Medics and coaches initially believed he was suffering from dehydration and a concussion. He was soon transported by ambulance to the hospital, where his condition rapidly worsened.

In the days following his passing, his family was left searching for answers. “We’ve had a few days of shock and lots and lots of tears and ‘why?’ and trying to understand like how this could have happened and how no one knows about this (rhabdo) and he didn’t know, and his gym didn’t know and everyone we talk to,” Sharone expressed.

She stressed the importance of awareness, explaining that if they had recognized the warning signs sooner, her son might still be alive. Determined to honor his memory, Sharone is now focused on raising awareness about rhabdomyolysis and potentially establishing a foundation in her son’s name.

“We’re going to as a family make sure his legacy lives on. We’re going to keep going with his dreams of helping athletes and inspiring youths to be great but also look after themselves because you can’t be great if you’re not here,” she said. “If he could be here I know he’d be changing lives so we’re going to continue that for him.”

In addition to his work as a personal trainer, Jake was studying to become a PE teacher and had earned his Certificate IV in Youth Work. He dedicated time to working with children and training adults, leaving a lasting impact on those he met. “I’ve had hundreds of people message me about the shock and how he has touched them and inspired them,” Sharone shared.

She hopes her son will be remembered as a driven and hardworking young man. “In pursuit of being the best he can,” she noted, describing his commitment to self-improvement. She recounted how he was always “full of energy” and “the light of the room.”

Tributes have poured in from the MMA community. Road to HEX, the organizer of Jake’s final fight, called him “a talented athlete and remarkable young man.” A shared Instagram post from Australian MMA and Mat Masters Academy described him as “a true warrior both in the ring and in life.”

“His generosity, strength, and unwavering support touched all who knew him. Jake’s silent battle with rhabdomyolysis ultimately claimed his life, but his spirit remains unbroken,” the statement read.

“You can honor Jake by raising awareness of this life-threatening condition and supporting his family through donations or by sharing his story. Jake’s legacy lives on in the strength and kindness he shared with the world. Rest in power, Jake. Your fight continues through us,” concluded the touching message.

A GoFundMe campaign, “Fighter, Coach, Warrior – His Legacy Lives On,” was launched to support Jake’s family and raise awareness about rhabdomyolysis. The fundraiser surpassed its initial goal of $20,000 AUD, collecting over $38,631 AUD (24,000 USD).

The campaign page described Jake as more than just a fighter — he was a dedicated coach, a beloved son, brother, and friend whose positivity uplifted those around him. Whether training with teammates, enjoying the outdoors or spending time at the beach, he was known for his boundless energy and selflessness.

Jake also cherished his personal relationships. An Instagram post from February 1, 2025, showed him posing with his girlfriend in front of a party backdrop.

The caption read, “Party + date night with my baby.” He frequently shared moments from his life, celebrating his successes and the people he loved.

In September 2024, he proudly posted about his kickboxing record after another victory in the ring. “3-0 Kickboxing now. Thank you to my coaches and teammates @matmastersacademy for always pushing me past my limits,” he wrote. His passion for martial arts and gratitude for those who supported him were evident throughout his journey.

Jake Sendler’s tragic passing highlights the hidden dangers of rhabdomyolysis and the need for greater awareness. His family and community remain dedicated to honoring his legacy by educating others and ensuring his story helps prevent future tragedies.