Rhabdo: The Silent Killer Fighters Need to Know About
On March 13, 2024, the combat sports world lost a rising star. Jake Sendler, a 21 year old amateur MMA fighter and personal trainer from Melbourne, passed away after an intense training block, his body ultimately overcome by a condition most athletes have never heard of: rhabdomyolysis.
Jake's story is heartbreaking and powerful. A fit, driven, and passionate young man, he was training hard for his upcoming amateur MMA bout. He felt sore, tired, and noticed tea colored urine. But like many fighters, he pushed through, assuming it was dehydration or normal fatigue. He made it through his fight, three full rounds, gloves raised to show he was still standing. But within days, he was in the ICU, placed in an induced coma, and tragically, lost his life. His family had never heard of "rhabdo." Neither had most of his gym.
Now, we need to make sure every fighter does.
What Is Rhabdomyolysis?
Rhabdomyolysis (often shortened to "rhabdo") is a serious and potentially fatal condition caused by the breakdown of muscle tissue. As CrossFit seminar staff this is a very important part of our Level 1 foundation course as well, for good reason. When skeletal muscle is damaged, whether by trauma, prolonged exertion, or extreme overtraining, it releases a protein called myoglobin into the bloodstream. In high concentrations, this protein is toxic to the kidneys and can lead to kidney failure, heart complications, and multi organ damage.
Rhabdo can also happen to anyone, but fighters, CrossFitters, soldiers, and endurance athletes are particularly at risk due to the intense and repetitive nature of their training.
Common Causes of Rhabdo in Fighters
Extreme high volume or High intensity training: Especially if it's a sudden spike in intensity or duration.
Training in hot, humid conditions: Dehydration and heat stress increase the risk.
Fasting or low cal training states (like weight cutting): The body has fewer resources to recover from muscle breakdown.
Heavy eccentric movements: Exercises like high rep GHD sit ups, sled drags, or intense pad rounds can cause microtrauma to muscle fibers.
Return to training after a break: Athletes returning too hard too fast after time off are at high risk.
Warning Signs Fighters Should Never Ignore:
Severe muscle pain and swelling (especially in the legs, arms, or lower back)
Dark, tea colored or Coca-Cola urine – a hallmark symptom
Muscle weakness or stiffness that doesn’t improve
Nausea, vomiting, or confusion
Difficulty breathing or chest pain
Jake Sendler experienced some of these signs, especially muscle pain and discolored urine, but dismissed them, like many fighters do. After all, soreness is part of the game, right? But rhabdo is different. It’s not just DOMS. It’s a red flag your body is breaking down at a cellular level, your coaches need to also be aware of rhabdo and of these symptoms.
Why Fighters Are at Higher Risk vs other sports
Combat sports demand a unique mix of strength, endurance, and grit. Fighters often pride themselves on pushing through pain and fatigue. But that same warrior mindset can make us blind to warning signs our body is sending.
Here’s what raises risk in fight camps:
Double sessions with high volume (conditioning + sparring + strength)
Water cuts and dehydration, especially when done incorrectly
Overtraining with insufficient sleep and recovery
Suppressed immune systems from calorie restriction or stress
Add these up, and the body can hit a breaking point, quietly, and quickly.
How To Prevent Rhabdo Without Compromising your Performance
Knowledge is power. Fighters can still train hard and smart with awareness and proactive strategies:
1. Build Intensity Gradually
Avoid major spikes in training volume. Ramp up intensity over weeks, not days. Track training load and deload when needed, Use coaches that understand your schedule and progressively build you up.
2. Hydrate Smart
Use electrolytes, especially in hot climates or when cutting weight. LMNT, Wilder, coconut water with salt, or homemade mixes work well. (7/11 “electrolytes” are not the real thing) Monitor urine color and volume.
3. Respect Recovery
Hard training without recovery is a recipe for disaster. Sleep 7–9 hours, eat enough to support training, and prioritize rest days.
4. Know the Signs
Educate your gym, coaches, and training partners. If you notice tea colored urine, extreme muscle pain, or any of the red flags above, get bloodwork (especially CPK and kidney function tests) and go to a doctor immediately.
5. Ease Back In After Time Off
Post fight, post injury, or post layoff, ease back with lighter loads, shorter sessions, and more rest. Don’t try to "make up" for lost time, this is especially applicable to fighters who like to take 2-3 weeks off after big fights.
Jake’s Legacy
Jake Sendler’s story, like others before as well, is not just a tragedy it’s a wake up call for the entire fight community. He was doing everything right, training hard, eating clean, living with purpose. But he, and most probably his coaches, like so many others, didn’t know about rhabdo until it was too late.
His family has committed to raising awareness so other fighters don’t suffer the same fate. Let his story make you more aware, elevate your training knowledge, and help you protect your teammates.
Fighters are warriors. But true warriors know when to listen to their body, and when to fight smarter, not just harder.
If you train in combat sports, strength & conditioning, or coach fighters, please share this article. Let’s make rhabdo known. Because knowledge might be the one fight we can win before it even starts.
