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The Science Behind “Uncle Pukie”

03 Dec Posted by in Helpful Tips | 11 comments
Strangely enough, this clown named "Uncle Pukie" has been named one of CrossFit's mascots...

Strangely enough, this clown named "Uncle Pukie" has been designated as one of CrossFit's mascots…

The following excerpts are taken from an article by Mary Boudreau Conover, BSNed, with a contribution from Lon Kilgore Ph.D. This article was originally posted by CrossFit Santa Cruz.


An athlete’s ability to reach maximal performance is a direct result of physical performance, stress tolerance, and immune function. The gastrointestinal (GI) tract is also part of the system that regulates adaptation and regeneration of the athlete. For over a decade at CF, hurling has been unofficially viewed as somewhat of a badge of honor with a pet name, photos, and T-shirts to commemorate the event.

Intense exercise causes decreased blood flow (ischemia) to the gastric mucosa. The result may be nausea, which at some point may progress to vomiting, stomach cramps and diarrhea-more than just impaired digestion. These symptoms can be severely and even critically compounded when hot weather and dehydration are thrown into the mix. Without sufficient blood supply the GI tract simply can’t function as designed, rejects its stomach contents, and in some cases the contents of the intestinal tract (diarrhea). The ischemia achieved by athletes in long endurance events also compromises the intestinal barrier, contributing to and compounding the GI symptoms.

The intestinal barrier. The stomach and intestines are lined with a protective barrier formed by an intricate combination of membranes, junctions, mucus, and immunological factors. Different types of stress can breach this barrier, causing increased permeability of the gut lining and allowing entry of harmful bacterial toxins into the blood stream. This distressing concatenation of events may in turn cause inflammation and systemic complications as well as the nausea, vomiting, bloating, bloody diarrhea, and cramping seen in up to half of all participants in endurance events. CrossFit WODs are an intimate union of anaerobic and aerobic lasting about 20 minutes. All the same, because of the intensity we may dip slightly into the GI effects of the long endurance events.

Dial it back. Our bodies can adjust to this challenge—the annoying nausea, vomiting, and diarrhea, if we back off intensity when the first symptoms of nausea appear. Just back off a bit and see if you’re OK. Don’t push it to meet Pukie; he’s not worth it. Crossfitters don’t quit, but we can dial it down. If we respond early enough, this may be all it takes to restore adequate blood supply to the stomach. However, if the symptoms persist, take a break and lie down before it progresses further. Wait until your system recovers, then finish the workout. If vomiting is inevitable, we have all seen that we do recover with no lasting damage. We eventually adapt, improve VO2 max, and get stronger.

Physiology of adaptation. More is appearing lately in the scientific literature about the impact of exercise on the GI tract, but very little is said about how our adaptation to GI ischemia takes place. One of many suggestions makes a lot of sense and is very compelling. There is an area in the brain that detects toxins in the blood and acts as a vomit inducing center among other functions. Some drugs, for example, morphine, activate this area. Studies in animals have shown that this area can be desensitized.

Hydration. I can’t close without at least a word on hydration and its affect on digestion. An elegant study out of The Netherlands has found that dehydration causes a delay in the emptying of the stomach. This in turn may result in exercise-induced nausea. It’s not a good idea to arrive for our workout in a dehydrated or NEVER an over-hydrated state (a dangerous condition). A very brilliant physician once told me: “Let thirst be your guide and pay attention to its prompts.”

1. Never give up on your CrossFit workouts because of nausea.
2. When nausea occurs, back off the intensity or if needs be lay down until you recover and then finish the workout. You will adapt and improve VO2 max!
3. While progressing in your personal nausea-abatement program, don’t skip your planned workouts.
4. Never arrive for workout right after a meal, dehydrated or over-hydrated. We have a very easy way to tell when we need fluids. It’s called thirst.

Today’s Workout:

Buy In- Buy-in: 3x [skip 100, 15 double crunch, 6 clapping pushups]

WOD – “Nicole”

Elite/Zone 3: AMRAP in 20 minutes: 400m run, max rep pullups

Zone 2: AMRAP in 20 minutes: 400m jog/run, max assisted pullups

Zone 1: AMRAP in 15 minutes: 200m walk/jog, 10 assisted pullups

Cash Out–  Overhead Squat 4×10 repetitions, increasing weight each set

100 Day Burpee Challenge:

Burpees today:  3

Buy-in: 6

Workout of the Day

  1. Amber12-03-09

    what kind of workout is this?? Is the aim to make us puke because I think this might possible. see you there for the torture 🙂

  2. Chris12-03-09

    This is awesome! Finally doing a workout that I’ve already done, and previously sucked at 🙂

  3. Sean Falconer12-03-09

    Hey Chirs, since you can actually do a decent amount of pull-ups now, you aren’t going to be able to get in your customary 20 rounds of running :-). Have to make up for it later I guess.

    Wish I could do this one, but resting up for Saturday. Need my muscles and hands to be in top form.

  4. Deanna12-03-09

    It was a cold one this morning. Some enjoyed the frozen bars and others didn’t. Way to go Chris you added 30 pullups from the last time you did the WOD. Congrats!

  5. b12-03-09

    great wod this am 7am crew!! i was scared but the cold wasn’t too bad.

    what i am scared of is that eric guy and his need to kick cam off the leader board. is there a story to this? those of you that have met him know that eric is pure mean!! you can get back on the board though cam!!! i beleive in you!

  6. Rob12-03-09

    I know in long ultra races GI problems are common – I suffer from nausea often after a race. Dehydration is a common cause.

    One cure that I’ve found is eating ice cubes! It shuts down your stomach and the nausea often dissipates.

  7. cam12-03-09

    Nice work Chris! Yeah it must have been cool clear and crisp at 7am!! It’s always good to get a run at a workout you’ve done before – seeing your progress is a great motivator.

    b, Eric is turning into a monster! It’s nothing personal against me though I’m sure – he’s just doing the workouts better than I am! I mean, when your name is on SO MANY leaderboards, there’s always the possibility of getting knocked down 😉


  8. Chris12-03-09

    Haha so true Cam, Eric is a monster. And yes it is really awesome to repeat a workout and see improvement, that is what it’s all about!

  9. b12-03-09

    what i learned today:

    eric is a monster
    cam is modest

  10. Jenbot12-04-09

    Good luck in the competition everyone!

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