TL;DR: I got rhabdo from crossfit last year. My CPK was 100,000 and I spent 5 days in the hospital. I wasn't overweight but I wasn't fit when I got it, and I got it during the first day of a beginner course.

Ask me anything.

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I did crossfit for a couple of months in 2010 and loved it, but I had to stop since I moved to a new apartment and the gym times wouldn't work with the longer commute. I always wanted to go back, so in June 2012 I started up again, taking the two-week beginner course (I wasn't in the best shape and I wanted to ease into it).

During the first day back, we went through a lot of basic movements and listened to the instructor talk about what crossfit was like. In the hour-long class, we spent the last ten minutes talking about rhabdomyolysis; what it is, the symptoms, the danger, common ways to get it, etc.

The workout of the day was tabata squats (20 seconds of as many BW reps, then 10 seconds of rest, repeat 8 times for a total of 4 minutes and 2:40 of exercising), tabata pushups, and tabata situps.

The squats were the one that got me.

The next morning, I couldn't walk, but that was expected since it was my first day back. I pushed myself quite hard (knowing what crossfit was like), but I wasn't competing with the people in my class, I was competing with myself. I took it easy and rested.

The day after that, I couldn't really bend my legs because of the extreme soreness, and walking down the stairs was neigh impossible. It took a while, but I took the subway to the office where there's a gym with a stationary bike, as slow biking was the only thing that would ease the soreness in my quads.

After 6 hours at work, periodically biking and reading online, I noticed my urine was coca-cola colored, and that it was the telltale sign of rhabdo. I knew that because the crossfit instructor drilled it into my head two days earlier.

I looked online for a hospital that my insurance covered, took a cab, checked myself in saying I had rhabdo, and I began a 5-day stay where I received lots of saline solution (1000ml 6x a day, IIRC) to help flush the myoglobin out of my body. Luckily for me, the hospital saw a lot of cases of rhabdo from not crossfit members, but prisoners. They have little else to do than workout extremely hard, and the hospital saw dozens of prisoners a year.

My creatine kinase was almost 100,000 (excess myoglobin is the problem, but high creatine kinase is a proxy for high myoglobin, and CPK levels are commonly checked). TFA is right in that the normal is < 100. IIRC, the doctors estimated I dissolved 5 lbs of muscle tissue into my bloodstream to get a CPK that high. I was bored in the hospital so I charted my CPK to determine when they'd release me: http://imgur.com/18HYKNr

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Many tests afterwards showed my kidneys are fine, and I haven't noticed (or read about) what the TFA describes as "flabbiness" or some sort of water retention in my legs. I also haven't noticed that my legs are weak; on the contrary, after lots of biking over bridges my legs are stronger than my squat days (at least when it comes to endurance, not power).

TFA is being a bit sensationalist and anecdotal about rhabdo being crossfit's "dirty little secret." To add another anecdote into the fire, everyone I know that does crossfit knows what rhabdo is, and rhabdo is mentioned in beginner classes multiple times; not only what it is, but the symptoms, what to do when you get it, and how, if left untreated, myoglobinuria can lead to acute renal failure and death.

I haven't been to crossfit in over a year, but TBH I'm itching to go back. I'm the kind of personality that will really push myself hard – probably harder than most – but now I know a little better and will hold back a tiny bit, especially when doing high reps of low weight.

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Update: My first crossfit experience was at Crossfit Virtuosity in Brooklyn, NY and I got rhabdo at The Black Box in NYC.

Also, my memory isn't so great as I thought. I took the class on a Friday and, that same night, moved into a new apartment. The combination of crossfit and carrying lots of boxes/furniture on the same day was probably the cause.