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As 2013 comes to an end, I figure I had a chance to write one more post considering all the “buzz” going on lately.

As you might have been able to see from some of my research, over the last year our team at KSU has spent a lot of time involved in CrossFit related research trying to answer some basic questions, for which we do not have a lot of objective answers.

Unless you have been living under a rock for over five-years, by now you have an idea of what CrossFit is (or at least an opinion!) and perhaps you may have given it a try once or twice!  You can find out more about CrossFit on their website.

What I would like to talk about here, is a big controversy that has been brewing over the last couple of years as to how ‘dangerous’ CrossFit truly is; which, in a way, may be fueled by numbers more than anything else.  This controversy has granted me the opportunity to be interviewed on several mainstream media outlets, the latest of which was recently published here.

Of course, everyone has their own opinion on this, and I welcome an educated dialog here.

Some will argue about the certification process (which I find it to be a Fitness Industry problem, not just a CrossFit problem); the lack of experience among coaches; and the high-intensity nature of the program, which may not be suitable for everyone.  This last point however can be highly contested considering everyone has the ability to “scale”, or modify, any workout based on their fitness levels (if you have been doing CrossFit and this is NOT the case in your facility, perhaps you should consider changing affiliates!).

As this is written, there is only one published study that provides insight to the injury rates associated with CrossFit (our team is working on a larger scale study).  This study by Hak and colleagues was recently published in the Journal of Strength Conditioning Research.  Although it is a good start, their findings are hard to generalize to the entire CrossFit population as they only surveyed 132 participants.  Nonetheless, it provides great insight to how “dangerous” this exercise modality can be.

However, what I think truly fuels this controversy is the lack of objective data to examine the dangers of CrossFit and the interpretation of the numbers that have been referenced.  It is no secret that exercise, any exercise – CrossFit included – has an inherent risk of injury; however, how those injuries are measured is important and must be reported accurately.

In epidemiology, which is the science responsible for measuring and studying distributions and factors that affect the health of a population, there are a series of measurements that allow us to examine the magnitude of a public health issue, such as the number of people who are overweight, or have heart disease. Although these are merely statistics and represent basic numbers to most people, how the information is obtained and presented matters.  Thus, I would attempt to answer some of these basic questions.

For the purpose of this post, I will limit the definition to two common measurements that have appeared in the CrossFit injury controversy – Prevalence and Incidence Rate.  There are several other measurements, but for simplicity we will limit this to these two.

Prevalence – represents the number of individuals in a population (group) that exhibits the outcome of interest at a specified period in time.  Simply, it is the number of individuals who have “the condition” and it is calculated as a percentage of the total number of people in the population:

       All cases during a period of time            = Prevalence
    Total population at same period of time
 
Example:
Number of people (cases) who report a CrossFit related injury last year = 50
Total number of people (population) who participated in CrossFit last year = 200

Therefore, the prevalence, or the percent of individuals who reported having a CrossFit related injury was (50/200 = 0.25 or 25%). This doesn’t take into consideration how often those 50 people (injured) participate in CrossFit.  Perhaps those 50 people are training for the Games and do three workouts a day, compared to the other 150 who just go into an affiliate once a day, two-times per week. These two groups certainly have different probabilities of being injured.

Incidence Rate – provides a measure of the rate at which people without a condition/disease develop such condition/disease (simply number of new cases) over a specified time interval (e.g. one-year).  To examine this, we need to know the total time of exposure for the condition, not just the total population as with prevalence.

    New cases occurring during time period     = Incidence Rate
    Total-time of exposure for condition
Therefore, in this example WE HAVE to know how long these people were exposed to the condition – in this example the “condition” is CrossFit.  So, how often did they participate in CrossFit over the last year? Let’s just say each person took two-weeks off and completed 50 weeks of training, attending three one-hour sessions per week (50 x 3 = 150 hours per person).
Example:
Number of people (cases) who report a CrossFit related injury last year = 50
Total-time of exposure = 50 x 150 hours per person = 7,500 hours of CrossFit

Thus, the incidence rate of injury among people participating in CrossFit in this example is 50/7500 = 0.0067 injuries per training hour.  Because this number is so small, we can convert this rate to something that will make more sense such as 6.7 injuries per 1000 training hours (we just need to move the decimal point to the right three places).  Which means that for every 1000 hours of CrossFit training, seven (7) participants may be injured.

These numbers are merely an example to show some of the ‘math’ involved in some of this research – trust me it is much more complicated than this.  And by no means they represent true injury numbers related to CrossFit.  But, I hope they serve to understand how this data is interpreted and should be reported, because simply — an injury rate is not just a percentage!

I hope everyone has a safe and happy Holiday Season and a Happy New Year!  Thank you for reading and look forward to many more posts in 2014!

Until next time #BeActive!

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