Anathlete'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.[1]
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. However, vomiting is at
least an abuse to the sensitive esophageal lining highly intolerant of
acid baths and possibly, when a frequent event, causing inflammatory
damage to that important sphincter separating the stomach from the
esophagus. [2]
Damage of the lower esophageal sphincter muscle leads to reflux and
consistent irritation of the esophagus leads to at least inflammation
and at worst esophageal ulcers.
Additionally, intense exercise causes decreased blood flow (ischemia) to the gastric mucosa[3]–swimmers
have known this for as long as I can remember. 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.[4]
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.1
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.1
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.
As you will see in a report from Dr. Lon Kilgore, 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. It is called the area postrema and it’s located in the medulla oblongota. Studies in animals have shown that this area can be desensitized. [5] Unfortunately, the effects of GI ischemia, desaturated blood oxygen, or lactic acid on the area postrema, to my knowledge, have not yet been addressed.
A SCIENTIFIC EXPERIMENT BY ONE OF OUR OWN
What we do have, however, is an email from Lon Kilgore Ph.D, who did a study in his laboratory at Midwestern State University, Department of Kinesiology involving
his own performance of 4 consecutive weeks, 5 days per week of
multi-modal CrossFit workouts to evaluate the affect on VO2 max. Dr.
Kilgore very generously took time to read this article. His response
is in the following two emails.
Email #1.
" I did a 4 week pilot study of blood oxygen desaturation to 91% or lower via CF training and its relationship to improving VO2 max .
The
first workout out off the blocks was Cindy (used as a bench mark) and
within 5 minutes I experienced relatively profound nausea. My strength
allowed me to work hugely faster than my oxygen handling systems could
and thus---severe vascular shunting away from the viscera and nausea.
Five minutes later I was back finishing the workout but at a slower
pace for sure.
Two
days later Diane (as Rx'd) kicked my butt about 7 minutes in for the
same reason, 225 lb. deadlifts and handstand pushups are easy but doing
so many so rapidly caused a repeat session of nausea and a dismally
slow time.
I
desaturated to 89-91% throughout those two sessions. What I think is
happening is that by the time you are experiencing nausea, you have
driven your O2 saturation too low (worked too hard) causing profound shunting away from the GI tract.
You
need to push just shy of that point, to the edge of nausea, to get the
maximal results, but pushing on into full on nausea and Pukie-town
slows down the work rate and makes you miss the target workload - and
thereby the fitness gain possible from that workout.
It
is inevitable that people will miss the mark and get nausea and ralph
their guts out every now and then. And that should be a learning
experience, they should learn about the sensations and the signals
their body is sending them so they can push the envelope with more
accuracy and avoid spending valuable training time rolling on the floor
nauseas or praying to the porcelain god.
After
I figured it out (took two sessions of nausea), I knew when to start
taking breaks rather than just brute forcing it. And it paid off, 33.4%
increase in VO2max in four weeks."
Email #2 at my request:
Daily log of nausea
Days 1 and 3: Cindy and Diane. Huge
and nasty nausea on days 1 and 3. The kind you lay on the bathroom
floor with. The kind reminiscent of a severe college all night bender.
Day 2: Not bad on day 2 (easier workout)
Day 4: Day 4 not bad either.
Day 5:
A running repeat day and kettlebell swings I believe and there was a
little nausea controlled by the trainer (Justin) telling me to back off.
After that it never reappeared.
<The “Justin” in Lon’s email is Justin Lascek, head of CrossFit Wichita Falls at Mark Rippitoe’s Wichita Falls Athletic Club.>
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.[6]
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
- Never give up on your CrossFit workouts because of nausea.
- 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; thanks to Dr. Kilgore, we have it on very good authority!
- While progressing in your personal nausea-abatement program, don’t skip your planned workouts.
- Never
arrive for workout right after a meal, dehydrated or overhydrated. We
have a very easy way to tell when we need fluids. It’s called thirst.
ACKNOWLEDGEMENTS
Lon Kilgore Ph.D,
deserves everyone’s thanks for sharing his very personal experience in
a respected scientific study involving CrossFit WODs and VO2 max. His observations on nausea are a gift. Thank you, Lon, for being a very brave and strong guinea pig.
Big credit is due Ronnie Boose
at CrossFit North Santa Cruz for his inspiration with a photo and an
excellent post on their web site (June 9). Thanks Ronnie, you really
launched this one—been waiting years for an opening!
Denver also deserves credit and acknowledgement for taking me one step further. Thank you, Denver!
Thanks to Kelly Starrett Ph.D for suggesting the area postrema. I hadn’t heretofore known about that fascinating spot. Love that word!
REFERENCES
Bi L, Triadafilopoulos G: Exercise and gastrointestinal function and disease: an evidence-based review of risks and benefits. Clin Gastroenterol Hepatol 2003, 1(5):345-355. Dept of Med, College of Medicine, University of CA at Irvine, Orange, CA, USA.