Tire CrossFit

Here’s the science behind why I don’t do CrossFit.

In April, I wrote an article detailing my criticisms of CrossFit, for which I received quite a bit of feedback, both good and bad. Some points led to further discussion, and some people trolled the page, while others actually learned something new. However, there still seem to be some misunderstandings and misconceptions that I want to clear up.

But first, I’d like to quote Dr. Kenneth Jay, who received similar feedback from CrossFitters to some of his articles. His words of wisdom: “No emotional attachment.” As he reminds us, “[B]e willing to abandon your opinion—because in science, you are not entitled to your own opinion; you are only entitled to what you can argue for.”

So without further ado, I’d like to address some common issues people had with my article.

1) It’s better than people doing nothing. Aren’t you happy to have them off the couch?

I love that CrossFit gets people excited about fitness. I love that it fosters a community of people working out together and motivating each other.

Does that change my opinion about its programming (or lack thereof)? Absolutely not. The benefits of getting people off the couch are outweighed by the stress that is being put on their bodies. The potential for injury in CrossFit is drastically increased when newbies jump into it, especially if their coach’s certification and knowledge is questionable.

Let’s say there is an overweight person sitting on a couch. When they are sitting on that couch, they have lots of options they can take to improve their situation. If they jump into CrossFit and sustain an injury that puts them back on the couch, the options they have are now limited. For some people who have experienced extreme injuries like rhabdomyalysis or stroke, their lives may be drastically changed and they may never be able to exercise again.

These are obviously extreme examples, but the concept is applicable to any degree of injury.  There are far safer and more efficient ways to get people off the couch and work them into routines that will better target their goals than a cookie-cutter WOD at extremely high intensity.

2) I saw so much improvement from doing CrossFit. It changed my life!

Of course you did. If you go from doing nothing to doing something, you’re going to see results. Studies have shown that untrained individuals show favorable responses to nearly any protocol implemented, and their gains are often at a very high rate. You could have achieved this result from nearly any exercise program.

Why did CrossFit work so well for you, then, when you didn’t personally see results from anything else you tried? The answer is found in the community aspect of CrossFit: you were accountable to someone, you had fellow sufferers, you had a community with which to compare your numbers and times.

The conclusion from this phenomenon, then, is that any benefits that you notice from CrossFit as a novice that you did not perceive in other training regimens is purely social and derived from a greater commitment to your exercise program. In the absence of that social factor, science tells you that initial physiological responses are essentially the same for any training program of choice.

So why not apply that same commitment to one that is tailored to your needs and goals, while keeping safety a priority?

3) My gym is different. My coaches teach proper form and stop me if I’m doing it wrong. My gym has an intro program everyone has to go through before they can do the WODs. If you haven’t trained at my gym, you can’t comment.

I can, because CrossFit has a very distinct style of training to which most gyms adhere. If you’re doing CrossFit, then you’re doing the WODs, which are posted on the main CrossFit website each day, or something very close to it. I can make the generalization because CrossFit has key similarities in its workouts that make up its fundamental flaws: lift many times, lift quickly, don’t rest, keep going until you can’t anymore. This is totally encompassed in the CrossFit term, AMRAP: as many reps as possible.

While this may not be an issue for a minute or two of push-ups or pull-ups, it becomes a big deal when it’s Olympic or Power lifts. Why? Because, as Kraemer et al. state, “Total-body exercises such as the power snatch and power clean have been regarded as the most effective exercises for increasing muscle power because they require fast force production to successfully complete each repetition.”

This means that these exercises require a great deal of force on each rep in order to perform them correctly, which cannot be maintained for high volume sets, such as those listed below:

Example WODs (from 2014 CrossFit Games qualifying rounds):

WOD 1: Complete as many reps as possible in 8 minutes of (Men/Women):

  • 135/95-lb. deadlifts, 10 reps
  • 15 box jumps, 24/20-inch?
  • 185/135-lb. deadlifts, 15 reps
  • 15 box jumps, 24/20-inch?
  • 225/155-lb. deadlifts, 20 reps
  • 15 box jumps, 24/20-inch?
  • 275/185-lb. deadlifts, 25 reps
  • 15 box jumps, 24/ 20-inch??
  • 315/205-lb. deadlifts, 30 reps
  • 15 box jumps, 24/20-inch?
  • 365/225-lb. deadlifts, 35 reps
  • 15 box jumps, 24/20-inch

WOD 2: 60 clean and jerks (135 / 95 lb.). Time Cap: 7 minutes

Workouts like those listed above are asking the body to try to hit peak force for more repetitions than what the physiology of the body allows. For example, Chiu et al. found in “The Fitness-Fatigue Model” that subjects exhibited decreased movement velocity, decreased peak force, and decreased rate of force development after just four sets of five repetitions of speed squats. If your rate of force and peak force decrease after just 20 reps of speed squats, with rest intervals, how can you expect to maintain fast force production over 30, 40, or 60 consecutive snatches or cleans?

Another study by Skurvydas et al. showed greater low frequency fatigue and subsequent reduction in optimal positions in subjects performing 100 drop jumps compared to 50 drop jumps, concluding that greater magnitude of exercises causes a deterioration in form and increase in muscle fatigue. Which means that if you’re doing the WOD, or anything like it, you are putting excessive stress on your body via sub-optimal form, accumulating fatigue effects, and lack of planned recovery time.

While each individual is different due to genetics, such a workout scheme over time will cause the body to break down. The question, then, is not will it have an effect on your body, but rather how long will it take to have an effect on your body? You may bully your body through a battle or two, but it is a war you will ultimately lose.

4) People just need to be smart about how they do the CrossFit workouts. People should evaluate their gym and their coaches and make sure they know what they’re talking about.

When you have people who have perhaps not worked out their entire lives or who have been casual gym-goers, you can’t assume that they know the right questions to ask, the right way to warm up, how to recognize signs of fatigue, when their form has deteriorated, or the smart time to stop the workout.

A good training method recognizes this and ensures that its instructors are adequately trained to educate their members on these subjects and assist them with applying these subjects to their training. A good training method meets people where they are and helps them get where they need to be without throwing them immediately into the deep end.

Studies have shown that trying to do too much too quickly leads to fatigue and overtraining because the body is not able to physiologically adapt to the stress. The result is typically extreme soreness and/or injury.  

Any good training method should be concerned with injury prevention and take measures to ensure that participants are properly evaluated before performing workouts to determine whether or not they are ready for the intensity of the prescribed workout. Any good training method should allow flexibility for those who have not yet adapted or adjusted. A good training method does not assume the participant knows proper progression.

Successful training programs are dependent on program design, proper instruction, setting goals, evaluation, correct exercise prescription, and progression aimed at individual-specific goals. The general principles of progression are purposeful variation, specificity, and the gradual increase of stress during training, so that demands on the neuromuscular system are progressively increased and not immediately shocked and shot.

Two predominant types of overtraining in resistance exercise are too high intensity and too high volume, which are both integral parts of CrossFit. Thus, there is no smart or safe way to do a CrossFit workout except to drastically alter it, in which case it’s technically not CrossFit. Classic CrossFit training is fundamentally wrong according to current scientific standards and methodology in the field of strength and conditioning.

I have a really big problem with the way that the CrossFit culture seeks to push all responsibility onto the individual members. They charge the average person with trying to find a good coach, asking the right questions about certifications, evaluating the workouts, evaluating themselves and their level of fitness, and evaluating the level of safety of workouts and boxes. Due to the multitude of information and misinformation in the fitness world, these are unreasonable expectations to have of the general public when their health is on the line.

5) There are good and bad coaches in every sport, not just CrossFit.

Well, of course. I don’t deny that at all. But the “fad” aspect of CrossFit has allowed it to grow too quickly and has made it easy for beginners to start coaching beginners. I’m not saying there aren’t bad personal trainers, but a personal trainer is likely not teaching you to do Olympic or power lifts with large amounts of weight and/or for speed.

In a study on strength training, Kraemer et al. point out that these lifts “require additional time for learning and proper technique is essential.” The exercises and workouts that CrossFit employs drastically increases the danger that comes with having a bad coach. The importance of having a qualified and knowledgeable coach is summed up by Pearson, et al., who point out that “[T]he effectiveness of any training program is defined by the ability of the strength and conditioning specialist to effectively use scientific principles as the basis for making a multitude of decisions on a day-to-day basis as to the individual progression of a resistance-training program for an athlete.”

I understand that some coaches and boxes are better than others, but it should be a corporation-wide requirement with oversight that does not currently exist. CrossFit, Inc., in an effort to evade liability and allow “free market function,” has essentially said that this task is neither their problem nor their responsibility and that they will play no role in quality control.  Instead, founder Greg Glassman has been quoted as saying, “Crossfit can kill you,” as well as stating: “We have a therapy for injuries at CrossFit—called STFU.”

Such blatant disregard for the safety and well-being of Crossfitters is wholly inexcusable. Why let your body take the beating of being a cash-cow to a pyramid business scheme that ultimately does not have your best interest in mind? Why allow yourself to be taken advantage of in order to benefit others? The point to exercise and athletics is to achieve health, fitness, and performance; therefore any properly developed training program should be 100 percent based on a concern and care for the individual and should be carried out with a mindset of selfless service.

At the end of the day, it is the workouts that I am ultimately concerned with: lack of personalization, lack of programming, lack of progression, too high reps, too little rest, and a focus on speed of completing exercises rather than quality of the exercise. These types of workouts, coupled with the probability of a coach with a weekend certificate, make CrossFit particularly dangerous.

6) All sports and athletic activities have a risk of injury. CrossFit isn’t any different. So should we not play football or run either?

It does not mean that at all. Of course, there is risk of injury in each sport, and even in the world of general fitness.

However, you cannot compare apples and oranges by comparing CrossFit to athletics. In order to compare injury risks, you would have to compare the injury rates in the strength and conditioning training for those sports. Athletes in sports such as football or track spend time in the weight room and on the track or field practicing and training in order to prevent injury during their actual performance and cause neuromuscular adaptations.

Strength training in athletic programs specifically targets weaknesses that lead to injury and underperformance. The difference is that CrossFit tries to make a sport out of this training, instead of viewing it as a method of injury prevention. By making strength and conditioning training into a competition of how many lifts you can do or how fast you can do them, CrossFit compromises these training goals and instead makes the participant susceptible to injury.

Additionally, athletes recognize the risk that comes with competing in their sport at a very high level. These people aren’t just trying to get “fit” by competing, they are trying to be in the top percentile of their sport and many times they are trying to earn their living by doing so. Are there very high rates of injury among football players? Absolutely, but I’m not taking an average person off the couch or out of the local gym and putting them in pads and sending them out into a game to get them in shape. I’m not going to grab a mom of three and put her in a track meet to run sprints or hurdles to get her to lose some baby weight.

However, CrossFit takes these people and puts them into high intensity programs with complex lifts and high reps of auxiliary exercises, whereas elite athletes develop over years and years of building on past progress while being guided by highly trained professionals. That’s the difference.


In conclusion, there has been much scientific work that addresses the fundamental flaws and resultant safety issues associated with CrossFit (on which more detail can be found on my blog. From lack of individualization to overtraining, there is a scientific basis for the argument against CrossFit and its random, “one size fits all” methodology. Exercise physiology is a complex topic to which I hope I have brought some clarity for the readers of my initial article.

My goal here isn’t to inflame people; my goal is to educate and to have a conversation about something that many people may not want to talk about. Many people don’t know the risks associated with CrossFit, and I want people to be able to make an educated decision. Ultimately, though, it is each person’s decision to make, and if the person accepts the risks and the stress that his/her body will have to endure, then that is the individual’s choice.

I love that CrossFit has been able to forge a cohesive community that is excited about working out, however, we have to make sure that our desire to be a part of something does not overcome our powers of reasoned thought.

Note: I thank and acknowledge my fellow graduate student, Phillip Scruggs, for his help in assimilating papers, facilitating discussion, and providing helpful edits during my writing process. For a more in-depth look at my research, please visit my website.

Erin Simmons has a Master of Science in Biology. She has worked for the Department of Defense as a contractor in a physiology laboratory, and she is currently working on her Ph.D. in Fisheries at Texas A&M. A former student athlete, she is a volunteer assistant coach for the national championship track and field teams there, and she has created her own brand of fitness and health advice with Erin Simmons Fitness.

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