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.
EXERCISE INDUCED NAUSEA AND VOMITING
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.”
Summary
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
