Three reasons why endurance athletes should avoid CrossFit


I’ve been a bit discouraged lately about my state of fitness after tearing my ACL in 2013. After several months off, I worked hard and regained enough fitness to climb, do long bike rides, and cross country ski at a reasonable level.

I am definitely not as fast as I was before my injury, though. And my endurance is lower. I’ve tried to maintain a good attitude about this, but it’s still disappointing.

I refuse to believe the naysayers, who want to chalk up my fitness to old age. After all, studies have shown that athletic performance for endurance athletes doesn’t decline until people are in their 60s or 70s if the person continues to train. I figured something must be missing from my exercise program – which mostly consisted of hitting the trails for some fast hikes up the local foothills.

I started looking around at what my peers were doing and discovered that many of them were CrossFit devotees. At first glance, it seems like a fitness dream come true. My brother is enthusiastic about working out and has gotten into a good routine, even though he has multiple competing demands on his time. Several of my girlfriends have gotten really strong. (One of them can do full pushups with added weight over her shoulders.) And did I mention my PT’s six-pack abs? I’d like all of that!

Given the number of CrossFit Groupons available, I started looking into it. According to

“The aim of CrossFit is to forge a broad, general and inclusive fitness. We have sought to build a program that will best prepare trainees for any physical contingency — not only for the unknown, but for the unknowable. After looking at all sport and physical tasks collectively, we asked what physical skills and adaptations would most universally lend themselves to performance advantage. Capacity culled from the intersection of all sports demands would quite logically lend itself well to all sport. In sum, our specialty is not specializing.”

Training for all movements, functional and specified, so your body is in all-around good shape. It’s constantly varied, high intensity functional movement. I dig it.  CrossFit didn’t invent cross-training, but their claim to fame is taking cross-training a step further by including “any physical contingency,” “the unknown,” and “the unknowable.” I like your style, CrossFit, I do.

It may surprise you to learn, though, that I am completely rejecting it as a method of training for climbing, distance biking and skiing. You should too, if your fitness goals involve excelling at endurance sports. Here’s why:

1. CrossFit is not effective at training endurance or strength

Before I rain on the CrossFit parade too much, I should say that it isn’t all bad. CrossFit features hard workouts that will in fact help someone get in shape, to a degree. It teaches a variety of real exercises that are challenging and much better than sitting on the couch eating potato chips. Can’t complain about that!

The problem is, there’s no evidence that the high intensity work promoted in CrossFit will yield performance gains for endurance athletes. Sure, CrossFit claims that the system is “empirically driven and clinically tested” which insinuates that the methods are scientifically supported. According to WebMD, however, “a review of the current scientific literature . . . shows no published studies about CrossFit in top-rated peer-reviewed strength and conditioning or exercise physiology research journals.”

In fact, looking at the research on high-intensity, circuit workouts, we see that CrossFit is not ideal for building aerobic endurance. These workouts are often called “Tabita sprints” or “HIIT” (standing for High Intensity Interval Training). When these programs are researched, researchers note that VO2max increases by a large amount and that certain aerobic enzymes also increase.

The trouble is, VO2max does not equal aerobic performance. Just because VO2max is increased or decreased, does not mean that performance will change to the same degree or even at all. This is borne out by research done by Vollard, et al in 2009:

“Moreover, we demonstrate that VO2max and aerobic performance associate with distinct and separate physiological and biochemical endpoints, suggesting that proposed models for the determinants of endurance performance may need to be revisited.”

This is a key concept to understand, because the studies cited by CrossFit track effects on VO2max but not performance.

Crossfit isn’t ideal for building strength either. In a CrossFit you do a bunch of exercises until your muscles burn and you feel exhausted. Anybody can go into the gym and kill themselves for 30 minutes, pat themselves on the back, and feel like they just worked as hard as they could.

An effective strength training program focuses on a systematic approach to weightlifting and incorporates progressive overload. The trouble is, CrossFit is the exact opposite of this. It is a random approach to exercise that doesn’t utilize progressive overload or account for the law of diminishing returns. This type of training ultimately sets people up to plateau below their full potential.

All of this is easy to ignore when you hear anecdotes about how CrossFit “worked for me” and “worked for so-and-so.” Humans are inexplicably driven by anecdotal evidence instead of empirical evidence. We should remember though not to confuse “what can work” with “what works best.”

For the unfit or formerly fit, CrossFit works great initially. People see results because it’s a very high stress workout. It’s also why you see results when you do insanity or any of those workout videos.  It isn’t that the exercises are super awesome targeted muscle sculpting patented exercises. Instead, it’s that the people who generally do them weren’t doing anything before.

What happens after the initial gains? We get stale, we stop improving, or our body breaks down, which brings me to my next reason for deciding not to do CrossFit.

2. The risk of injury is too high

CrossFit incorporates a lot of Olympic lifts for extremely high reps and/or for time. We never see this in Olympic lifting gyms, because somewhere along the way they figured out it was a bad idea.

When power athletes are training in the gym, they do not load up the bar with a light weight and do snatches or cleans for 50 reps. These movements are the most advanced training one can do. The Olympic lifts tax your central nervous system a tremendous amount. Worldwide, the protocols of an Olympic lifting program agree on a main principle: higher weight, less reps.

CrossFit, unfortunately, does the exact opposite. Any time you are performing lifts against the clock, you are asking for your form to break down. When people are tired, they have trouble simply walking. Forcing someone who is fatigued to engage in power exercises like Olympic lifts or box jumps seems like a bad idea. Common sense says that putting a weighted bar in their hand and asking them to rip it from the floor to overhead as quickly as possible is a recipe for injury.

Sure, I hear people say that “the workouts are scaleable,” meaning I can and should do an easier version of the prescribed workout. The scalability argument is irrelevant, though. If poor workouts are scalable, they’re still poor workouts (just a little less poor, perhaps).

3. Other training methods are empirically better

There is a reason that ultramarathoners, Tour de France competitors, and other elite endurance athletes are not doing CrossFit. I’ve even heard that CrossFit Games competitors do not rely on CrossFit to help them win. If CrossFit was the best way to train for endurance sports, you better believe these athletes would be doing it. Instead, they train in other ways. Why? Because it works better.

Just what is this better way? Stay tuned. I’m reading, scheming, planning, and starting a new training program. I’ll let you know how it goes.

Photo by Runar Ellertsen, used with permission.

23 comments for “Three reasons why endurance athletes should avoid CrossFit

  1. Eric Lansford
    February 22, 2015 at 5:43 pm

    Good day,

    Allow me to shed a little light on CrossFit from a 45 year old guy. I started CrossFit 2+ years ago to get myself back into shape. Let me just preface the rest of this response by stating it definitely has helped.

    As I sit here and read the article above, I see the majority of the responses are from individuals who appear to have never given an earnest effort to try CrossFit. I do not believe the author has either. That is unfortunate.

    To begin, let us all understand what CrossFit is designed to do. It is designed to get you into shape and it will. Are you going to become an UltraMarathoner and run 100 miles from doing CrossFit. No. Are you going to ride ~2500 miles in the Tour de France from doing CrossFit. No. Does CrossFit teach people Olympic Lifts. Yep. Does CrossFit do all kinds of various exercises that will increase your physical and cardio capabilities? Yep again. Can you get hurt doing CrossFit. It is definitely a possibility…probably less than me trying to run 100 miles. I cannot imagine running that far in one outing… and I would be willing to guess neither can 99% of the people who will read this could either.

    I would also guess 75% of the time when a person is doing the “work-out of the day” (WOD), it does not include heavy weights. When the workout does include weights, just be smart about it. Nothing says I have to lift what the 20 year old next to me is tossing into the air. Cut the weight in half or just use an empty bar if need. No one is going to care.

    Here is where I see people getting hurt. It is traditionally the 30-40 year old guys who waltz into the gym and state right away they use to be a bad-@ss in high school. “I use to be able to squat 300 and dead-lift 500 lbs”. He begins working out and over the course of a couple of months regains some strength and then proceeds to try (and fail) at dead-lifting 400 pounds and subsequently hurts himself. Bummer.

    Just be smart about whatever sport or exercise you elect to participate in and know your limits. Have a good instructor, take your time and chances are you will be happy with what you can do.

    These are just my thoughts…


    • Carry
      February 23, 2015 at 8:15 am

      Eric: Thanks for your thoughts on CrossFit. I think you missed the point of my article, which was aimed specifically at endurance athletes – the people who do want to run a marathon, ride long distances, or climb continuously many days in a row. (These are the people who are commenting on my post.) I didn’t say all athletes should avoid CrossFit, I said endurance athletes should avoid CrossFit. No doubt unfit and formerly fit people will see some fitness gains by doing CrossFit, like you have. They will not be able to use CrossFit, however, to get in shape for a 50-mile xc ski race, a 200-mile bike ride, or even a modest goal like a one-day alpine style climb. It’s just not designed to do that.

      • Eric Lansford
        February 23, 2015 at 10:55 am

        Hi Carrie,

        Thanks for the response. You are correct. I misinterpreted the point of the article. Forget posting my response.

        Hope your day is a good one.



  2. Eric D
    March 15, 2015 at 9:48 am

    Hey Carrie, a little late but I’ll chime in as someone whose strength and endurance has noticeably improved as a result of CrossFit. I agree with others’ comments that more study is necessary before any of these anecdotes can be used to make broad-based claims across a population, but I can say it worked for me, and it may work for others.

    So how did CrossFit help me improve my endurance and ability to climb mountains all day, ride bike races like RAMROD, ski tour, etc? Here are a few big factors:

    1. I’ve learned about my body and improved core body mechanics. I’ve learned what movements are my strengths, and where I struggle. Learning how to do to a proper Clean & Jerk exposed strength and flexibility issues in my hips that my trainers worked with me to improve. Those same flexibility issues were impediments to my skiing. On the slopes I overcompensated with other muscles (using my legs to muscle through turns even when I wasn’t well balanced and positioned due to my hips). Addressing the root cause improved my ski form and improved my endurance by taking strain off other muscles. Ironically, I had many ski instructors for years attempt to fix this issue in my ski form, but a ski instructor can’t make you be more flexible and improve your range of motion in a one day class. It was a CrossFit coach that helped me really deconstruct my body mechanics and give me tips to improve over time. In addition, CrossFit has helped me with my balance, mobility, and helped me engage and activate muscles that I rarely use. Those 45-pound ice climbing packs still hurt, but they hurt a little less.

    2. I’ve learned a lot about nutrition and how it impacts my performance. Our coaches post a daily blog that includes the next day’s workout, but also some tips on increasing performance. For a while I ignored the implications about my diet — “Hey, I’m a generally healthy guy and I’m not competing.” But eventually, as an experiment, I altered my diet to be mostly lean meats and veggies. The cool thing about scoring workouts and revisiting them over time is you can see your own progress. And I was surprised at what a difference food makes. Quickly. I learned, sadly, that beer hurts my performance the next day a lot more than wine does. I’m not the most adamant follower of the paleo diet, but I do think about it more in advance of my outdoor adventures.

    3. I lost 17 pounds. That made a pretty big difference in my endurance events. I didn’t know I had 17 pounds to lose. I didn’t diet. All I did was exercise 3-4 times a week and switch to eating more healthy foods (although I always ate as much as I wanted).

    4. I have measurably improved my strength in many core movements. I agree with the point you make that high-intensity workouts are not where strength gains are made, but the high-intensity WOD is only about 10-20 minutes of the hour-long time I spend in the gym, and it’s normally near the end. Our gym generally follows a progression of: 1) Warm-up/flexibility work; 2) Low-intensity strength work; 3) WOD; 4) Warm-down/flexibility.

    There are downsides. Your point about the risk of injury is well-taken. The same scoring system that helped me learn so much about my diet and my own performance can also be a source for unhealthy competition. I was once doing so well on a workout and beating everyone in my class, and I got a huge adrenaline rush and got all hyper-competitive and tried to finish first and I overdid it. Not only did I tire out and not finish first, but I also was so sore that when I went to Whistler that weekend, and there was 8 inches of fresh powder, my legs were so sore that I couldn’t ski well. A CrossFit friend and coach from another gym, hearing the story, put it this way: I forgot that I go to the gym to improve my life outside the gym, not to win inside the gym. You have to listen to your body. I didn’t and I paid the price. This is not CrossFit’s fault or my coaches’ fault — they continually stress that despite the clock, the goal is quality movement, good form, scaling weight and reps to the needs of each person. Your point about form breaking down while competing against the clock is true in some cases, but it is something that the coaches in my gym very much counsel against. If my form is breaking down, I’m generally told to stop and take weight off until I can complete the movement in proper form, or just stop altogether. I have had a coach come up to me mid-workout and ask me “What’s wrong with your knee?” and when I said “Why?” (I wasn’t really aware I was out of balance), he said, “Well, I can see you’re using the other one more.”

    CrossFit is my only non-weekend-warrior training activity and I can see the results in my all-day excursions. In February, I was ski touring in “considerable” avy conditions. It came my turn to break trail, and I was stomping through deep snow on a lee slope. Our party was using safe travel techniques in avy terrain, so every time I got a bit winded (especially in the lee areas where snow had piled up), I’d turn around and see the party was safely separated. Each time I decided I wasn’t tired enough to be bothered to find a safe spot and wait for them, and I’d just press on breaking trail. 2500′ later we reached the col and I was ready for a short break. As the party came up I could see most were much more tired than I was, even though I broke the trail. One guy I’ve been climbing with for years, who is considerably younger and has generally been the person who breaks trail while I followed along out of breath, remarked at the top: “Wow, Eric, that CrossFit has really made a difference for you.”

    It has. Since starting CrossFit, my strength, confidence and stamina in the backcountry have increased. I have no concerns getting a call on a Thursday about single-push, 18-hour car-to-car, ice climb/ski descent of Baker (climb N Ridge, descend Coleman) that coming Saturday. My body awareness has improved which has helped ski form. And CrossFit is my main training tool all year long to help me get ready.

    Do I compete in CrossFit, or in endurance events? No. If I did, I’d need more investment in the specific events in which I’d be competing. But in terms of improving quality and performance for “weekend warrior” endurance events, CrossFit has certainly helped me by giving me tools to improve strength, flexibility and nutrition.

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