In a previous article, I wrote about the disadvantages of Crossfit, and the risk of injuries due to the rather unstructured way the workouts are composed. In my quest for research on this, however, I found nothing, at least no scientific, “peer-reviewed” studies. Coincidentally, yesterday the summary of the first study on this appeared, the full report of which will be published soon (1).
Table of Contents
Injuries from Crossfit
The fact that I couldn’t find anything about this earlier seems not to be due to my limited abilities. The researchers chose their topic because nothing was known about it while there was enough reason. They wanted to gain insight into the number and types of injuries sustained during Crossfit training.
There has been much criticism as to the potential injuries associated with CrossFit training including rhabdomyolysis and musculoskeletal injuries. CrossFit training including rhabdomyolysis and musculoskeletal injuries.
P. Hak
However, I have strong doubts about the representativeness of the study.
“Uncle Rhabdo”
Before I delve into the study, I need to tell you about “Uncle Rhabdo,” the unofficial mascot of Crossfit. Crossfit itself may contribute the most to the association between Crossfit and injuries. Uncle Rhabdo is named after the condition rhabdomyolysis.
This is a condition in which muscle mass breaks down very rapidly.
Literal: The destruction or disintegration of striated muscle tissue (2). This breakdown and necrosis (death) of muscle mass result in breakdown products of muscle tissue (myoglobin) entering the bloodstream (3). This can then lead to kidney failure and be life-threatening (4,5). The most common causes (in the US) are cocaine use, immobility (long periods without movement such as victims of natural disasters getting stuck), and intense physical exertion (6).
Uncle Rhabdo is a clown who, after an intensive workout, needs dialysis (kidney replacement therapy) due to kidney problems caused by rhabdomyolysis. It is an expression of the do-or-die attitude of Crossfitters and is based on the number of reports of people needing dialysis after Crossfit workouts. Striving to the extreme seems to be the motto.
Rhabdomyolysis due to exertion is seen, for example, in (ultra-)marathon athletes and elite military units. People who are pushed to the extreme and go far beyond healthy exertion.
It is these kinds of expressions (like the earlier mentioned STFU-therapy, Shut The Fuck Up-therapy, for injuries) that have given Crossfit the image of reckless exertion.
Earlier this month, an article appeared stating that Crossfit is good business for chiropractors and physiotherapists due to the high number of injuries (7). “Good business because the clients keep coming back,” according to chiropractor Robert Hayden.
It is not surprising, therefore, that the researchers chose the number of injuries among Crossfitters as a subject and specifically looked at the number of cases of rhabdomyolysis.
Setup of the study on injuries from Crossfit
An online survey was sent to international Crossfit forums. It asked about characteristics of the Crossfitter such as gender and age, training programs, types of injuries sustained, and use of supplements. They received 132 completed surveys in return.
Not a large response, so questions can be raised about the representativeness of the study, but it’s at least something.
One may also question how honestly the survey is answered. The people filling it out know damn well what it’s for. They know from experience how often Crossfit is accused of poor techniques and susceptibility to injury. In other articles like “I hate Crossfit,” I described how (practitioners of) Crossfit can exhibit cult-like traits. If you were to ask David Cordesh’s followers (from that group in Waco, Texas) if they ever doubted him as a messiah, you wouldn’t expect to hear any criticism.
The results
Of the 132 people who completed the survey, 97 had suffered injuries at some point (73.5%). Together, these 97 people had sustained 186 injuries, of which 9 required surgical intervention.
At first glance, this may seem like a lot, but this must be considered in terms of the period and the number of workouts in which they were sustained. The researchers therefore also looked at the total number of training hours. They calculated that for every 1000 training hours, 3.1 injuries occurred.
The summary does not state how long and how often these people train, but based on the times I see on forums, I’ll assume it’s around 45 minutes to an hour. For ease of calculation, I’ll use an hour here. So, if you train four times a week for an hour each time, we’re talking about 250 weeks of training with 3.1 injuries occurring. That’s slightly less than one injury every one and a half years.
No cases of rhabdomyolysis were reported. However, this isn’t surprising in such a small sample. In the US, for example, there are around 26,000 cases of Rhabdomyolysis annually (8). Based on the US population size in 2010 (over 300 million), you’re talking about 0.008%. This means that on average you would need a sample of 12,500 people to find one with rhabdomyolysis. Moreover, the vast majority of these cases are not caused by exertion, but by pesticides, medication, and drug use. In practice, you would likely need a sample of at least 25,000 people to encounter one case. In a sample of only 132 people, you would only come across such a case if it occurred almost 200 times more frequently in Crossfit (25000/132). This would mean that rhabdomyolysis would occur in 1.6% of all Crossfitters. If that were the case, the dialysis equipment would be flying off the shelves. The sample was too small to say anything about the number of cases of rhabdomyolysis caused by Crossfit.
Back and Shoulder Injuries
To put the number of injuries into perspective, the researchers indicate that this is comparable to the number of injuries among weightlifters, powerlifters, and gymnasts and lower than the number of injuries in contact sports such as rugby (but that’s saying something).
Especially shoulder and spinal injuries were common. This does not surprise me considering the types of exercises often involving lifting above shoulder level and the many deadlift-like movements performed at speed (such as flipping tractor tires).
My Personal Conclusion
It’s nice that research has finally been conducted, but I still have my doubts, and not just because I want to be right.
Firstly, I would have liked to see the sample much larger. Although the summary does not indicate how many potential respondents the survey was sent to, I assume the researchers would have liked more responses too. A sample of 132 people is very small, too small in any case to say anything about specific things like the rare rhabdomyolysis.
Secondly, the results do not align with the experiences as proudly reported by many Crossfitters on forums and the experience of doctors, chiropractors, and physiotherapists who until recently had never heard of Crossfit and now see their income rise thanks to this new fitness hype.
It’s a good start, but I would like to see more and larger studies on the number of injuries caused during Crossfit.
References
- Hak, Paul Taro MBChB, MRCS; Mr; Hodzovic, Emil MBChB; Dr; Hickey, Ben MBChB, MRCS; Mr. The nature and prevalence of injury during CrossFit training. Journal of Strength & Conditioning Research: POST ACCEPTANCE, 22 November 2013. doi: 10.1519/JSC.0000000000000318
- Farmer J: Rhabdomyolysis. In In Critical Care. 2nd edition. Edited by Civetta J, Taylor R, Kirby R. Philadephia, PA: Lippincott; 1997::1785-1791.
- Warren J, Blumberg P, Thompson P: Rhabdomyolysis: a review. Muscle Nerve 2002, 25:332-347.
- Huerta-Alardín AL, Varon J, Marik PE (2005). “Bench-to-bedside review: rhabdomyolysis – an overview for clinicians”. Critical Care 9 (2): 158–69. doi:10.1186/cc2978. PMC 1175909. PMID 15774072.
- Bosch X, Poch E, Grau JM (2009). “Rhabdomyolysis and acute kidney injury”. New England Journal of Medicine 361 (1): 62–72. doi:10.1056/NEJMra0801327
- Gabow P, Kaehny W, Kelleher S: The spectrum of rhabdomyolysis.Medicine 1982, 62:141-152.
- http://www.examiner.com/article/rise-crossfit-injuries-a-boon-for-chiropractors
