There’s been a lot of press linking CrossFit and the risk of contracting a condition called rhabdomyolysis, an extremely rare medical condition that occurs when muscle tissue breaks down and the contents of muscle cells are released into the bloodstream. One molecule in particular, myoglobin, is toxic to the kidneys and can, in only the most severe (and rare) cases, cause kidney failure.
Symptoms include swelling of muscle tissues, extreme soreness and dark-coloured urine and it is important to seek medical attention if you develop these.
This condition is not something that CrossFit tries to hide, quite the contrary. There are numerous journal articles posted on CF headquarters site that deal specifically with this issue so coaches and participants are educated about it.1 Is there a risk of developing this condition when doing intense exercise of any sort? Yes, but reported cases are extremely rare and all CrossFit coaches learn not only about the risks, but also how to avoid them.
“Uncle Rhabdo”, a cartoon depiction of a rhabdo-sufferer, serves as a reminder to affiliate owners and CrossFit coaches that the possibility of contracting rhabdomyolysis is a legitimate risk if proper precautions are not taken.2
Risk of Rhabdo Not Limited to CrossFitters
“Although rhabdo is….a rare condition, the truth is that many athletes suffer from a mild version of it from time to time. ‘If you’ve ever had stiff and tender muscles after exercising, you’ve probably had a slight case of rhabdomyolysis,’ notes Marc Rogers, Ph. D., an exercise physiologist at the University of Maryland.” (This is commonly referred to as DOMS – Delayed Onset Muscle Soreness.)
“Moderate cases of rhabdo are probably common after triathlons. For example, when 25 triathletes were studied during a triathlon which included 2km of swimming, 90km of biking, and 21km of running, it was found that most of the participants had unusually high levels of myoglobin in their blood immediately after the competition, suggesting that muscle-membrane leakage had occurred. Other studies indicate that rowers and cross-country skiers are susceptible to rhabdo, and some reports have indicated that acute rhabdomyolysis can strike about one out of every 300 military recruits during their first week of training.
Alcoholics and drug addicts are prone to the condition and can develop an extensive case of rhabdomyolysis just by sleeping for an extended period on one side of the body (the pressure on the ‘down’ side of the body is apparently enough to trigger muscle problems in these groups of people). Severely injured accident victims often experience rhabdo, too, usually because a crushing injury has damaged muscle cells and caused leakage of cell contents into surrounding tissues.
Strangely enough, a small dose of rhabdomyolysis might actually have a positive effect. Various scientists have speculated that the build-up of calcium inside muscle cells during rhabdo can stimulate increased protein synthesis inside the cells, perhaps producing some of the beneficial adaptations we associate with training (more aerobic enzymes, more contractile proteins, more mitochondria). It’s only when too much damage is done and the whole process gets out of control that rhabdo becomes a severe threat to health.
Studies … suggest that as fitness improves, and an athlete’s training program becomes more challenging and of longer duration, the likelihood of rhabdo declines.” 5
What does CF Kitchener do to reduce the risk?
“The athletes at highest risk seem to be those with a reasonable baseline level of fitness they have obtained through some non-CrossFit training, or those who are returning to CrossFit after a layoff.” 3
- We assign a trainer to anyone coming in for a Trial Class so the workout is scaled appropriately for them
- Our introductory classes and sessions provide shorter, less intense workouts to gradually build participants’ ability to handle the workload associated with our regular programming
- We encourage recent graduates of our introductory training to continue to scale workouts (including rounds, reps, load, and movements)
- We remind members returning after an absence to scale back their workouts
“Eccentric movements are particularly stressful for muscles because the muscle cells are lengthening while trying to contract.” 3
- Our programming follows a template that rotates not only the different exercises but also takes into account the way a muscle is contracting: concentric, eccentric or isometric contraction
“Other rhabdo invitations are intense exercise after a recent infection, heavy alcohol consumption, exercising in extreme heat and humidity, insufficient hydration before and after a workout, cocaine usage, and the use of a cholesterol lowering drug called Mevacor (lovastatin is the generic name).” 4
What can you do to reduce the risk?
- Take appropriate rest days
- Hydrate, hydrate, hydrate
- Scale back workouts for a week or two after an absence and especially after coming back from an illness
- If you are new to CrossFit, no matter what your current level of fitness, scale back on your initial workouts – ask the trainer to help you with this
- Listen to your body – if you are reduced to doing 1 rep at a time perhaps it’s time to stop or take some weight off the bar
- Be aware of symptoms and seek medical attention if you develop these symptoms: muscle swelling, extreme muscle soreness, dark-coloured urine (often described as coke-coloured)