“The Nature and Prevalence of Injury During CrossFit Training,” Dr. Paul Hak, Part One

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The Journal of Strength and Conditioning Research recently accepted a study titled “The Nature and Prevalence of Injury During CrossFit Training.” The authors, Mr. Paul Taro Hak, Dr. Emil Hodzovic, and Mr. Ben Hickey, are based at the All Wales Trauma and Orthopedic Training Program in Cardiff, UK. It has been published as an abstract (ahead of print).

Of 132 respondents, 73.5% reported having sustained injury during CrossFit training. What the authors did get correct is noting the statistical difference between prevalence of injury among a survey group, and an injury rate, which they calculated as 3.1 injures per 1000 hours training. For an explanation of the difference between these terms, read Dr. Feito’s blog post on the subject.

As Dr. Will Hopkins, Prof. of Research Design and Statistics states:

“An injury rate is the number of injuries over a period of time divided by a measure of the total exposure to sport during this period. The measure of exposure is athlete-time at risk: the total number of athletes (injured and uninjured) multiplied by their average participation time, expressed as the number of practices and/or games or as actual time spent in these activities.”

This simple statistical difference between the injury rate and injury prevalence within a sample group has gone over the heads of many, including Discovery News host Trace Dominguez, Chiropractor Lucas A. Hilt, Pike Athletics co-owner Allan Phillips, Jason Tremblay of “The Strength Guys”, Physical Therapist Nicholas Kent, and the authors of the ironically titled study “Injury Rate and Patterns Among CrossFit Athletes.”

Injuries in CrossFit do happen, but they appear to happen at the same rate as injuries in general fitness training.  Photo Credit: Kenneth Nyberg

Photo Credit: Kenneth Nyberg

So how does 3.1 injuries per 1000 hrs. of training compare to other forms of exercise? The paper rightly concludes that these rates are “broadly similar” to reported injury rates for weightlifting, powerlifting, gymnastics, triathlon training, as well as “adult fitness activities”, and “general gym/fitness club training.” In other words, this study (even with the possible bias towards a high injury-rate) concludes that CrossFit is no riskier than any other form of exercise.

This, however, is not the end of the story. The full text of the study has already surfaced here, and there are some serious problems with it. I also conducted an interesting interview with Mr. Hak that may explain why, Part 2 will cover both.



  1. Let’s clarify what 1000 hours means in terms of CrossFit. A dedicated CrossFitter who goes for five one-hour sessions per week is training 260 hours per year. So 1000 hours means four years + eight weeks. For sports like cycling or distance running (or soccer or powerlifting) the average hours per year could easily be far, far higher.

      • John

        Actually Russel, your math is flawed. 1000 hours / 3.1 injuries = ~322 hours/injury. So, no, not 4 years, more like 15 months. That is assuming that every person gets injured at the same rate of course. Hopefully none of are that unfortunate and use good form whenever able and quit when unable.

  2. Pingback: “The nature and prevalence of injury during CrossFit training,” Dr. Paul Hak, Part Two | THE RUSSELLS

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