We Read Research So You Don’t Have To

When CrossFit sued the NSCA, scientists reacted in two ways. Dr. John Porcari warned that scientists “shy away from studying” CrossFit “because [CrossFit leaders] are so aggressive in their attacks on anybody who says anything bad about CrossFit.” In contrast, Dr. Katie Heinrich doubted that legitimate scientists had anything to fear: “the lesson learned is: Don’t make stuff up.”

The idea that accountability for fraud would cool research on CrossFit now seems laughable. Research in CrossFit has exploded. Witness the long list of recent research that appears when searching for “CrossFit” (Pubmed). Does the new batch of research offer any insight to a CrossFit affiliate member? Let’s take a look at two recent publications.

Study #1:  “Attentive processes, blood lactate and CrossFit®.” 

This Italian study found that CrossFitters exhibited high lactate levels before CrossFit Games Open workout 15.5, relative to normal resting lactate levels. Yet it did not mention if/how they warmed up, though it acknowledged that CrossFit workouts do normally contain warm-ups. If they warmed up beforehand, the subjects were not truly in a resting state. The subjects lied on the ground for 15 minutes prior to the pre-workout blood test, but that may not have been enough to return the subjects’ lactate levels to their true resting levels. The lactate level in the blood “remains elevated for over 60 minutes” after intense exercise.  A standard CrossFit warm-up, though not maximal exercise, could keep lactate levels elevated above resting levels for 15 minutes, thus making the researchers’ concerns about “resting” lactate levels baseless. The researchers did not mention this factor.

The mean WOD time was 14:34–a beginner to intermediate result for a workout that elite athletes complete in 5-6 minutes. This result calls into question the experience of the subjects as well as their compliance to training and nutrition–two more topics the researchers failed to address. Their study tested attention and mental capacity prior to and following the WOD. It will surprise no one who has thrustered that the subjects’ reaction times and mental capacity were impaired after 27-21-15-9 each of rowing calories and 95-lb. thrusters. A useful study would compare the post-WOD mental performance of experienced CrossFitters with that of newer trainees. Do experience with CrossFit and/or fitness level affect the mental response to intense exercise?

Games2012_DanBailey_thruster_Fran.jpg

Thrusters make it hard to think, as anyone who has thrustered knows.

Study #2: The role of social capital and community belongingness for exercise adherence: An exploratory study of the CrossFit gym model” 

Researchers from Cardiff in the UK compared the social capital at a globo gym with that at a nearby CrossFit affiliate. Social capital is a nerdy way to say community. In other words, social capital refers to the trust and mutual support that develop from social connections. The study found “ratings for all social capital and general belongingness scores were higher” for the CrossFit gym compared to the globo gym. This claims to be the first academic study to measure the community benefit of CrossFit that CrossFitters have talked about for over a decade. Unexpectedly, both the CrossFit group and the globo gym group attended the gym at similar rates, though. This surprised the researchers since social connection normally correlates with increased exercise compliance.

Selection bias may explain why the globo gym exercisers exercised regularly despite significantly lower social engagement. The researchers “approached” exercisers inside the gyms to invite them to participate in the study. This means the study had a significant selection bias–they tested that rare animal, the globo gym member who regularly attends. The researchers only recruited members present at the gym instead of drawing from the overall database of gym members, but most globo gym members do not regularly attend. As NPR explained,

Gyms have built their business model around us not showing up. Gyms have way more members than they can actually accommodate. Low-priced gyms are the most extreme example of this. Planet Fitness, which charges between $10 and $20 per month, has, on average, 6,500 members per gym. Most of its gyms can hold around 300 people. Planet Fitness can do this because it knows that members won’t show up. After all, if everyone who had a gym membership showed up at the gym, it would be Thunderdome. If you are not going to the gym, you are actually the gym’s best customer.

Similarly, Stefano Della Vigna and Ulrike Malmendier found that members in both monthly and annual contracts attend just over once a week on average.

The CrossFit affiliate business model is the globo gym’s polar opposite. A Globo gym relies on members not attending whereas a CrossFit gym depends on its members finding deep value in their memberships and thus regularly attending. CrossFit gyms cost much more than globo gyms such as Planet Fitness, so CrossFit members are less likely to pay and not show up. And thus, CrossFit affiliates were found to provide significantly higher social engagement, not to mention the higher enjoyment levels previously found in CrossFit exercise. If scientists want to test real globo gym attendance, they should begin with a pool of all registered globo gym members, not the small minority present at the gym.

So what have we learned? CrossFit workouts can make it hard to think afterwards, and CrossFit affiliates build a vibrant community around intense exercise. I suppose it’s nice the peer reviewed literature caught up to these realities.

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