Wow! It's only mid April and we're already hitting record temperatures outside! Austin will be seeing 97 degrees today (April 17th) and Dallas is hitting 100! What better time to bring up some more information that can help everyone out there with hydration and common issues involved with exercise and the heat! Here is the latest article by Dr. Stoddard which will be seen in the May '06 issue of "The Racing Post".
www.theracingpost.usEnjoy!
Dr. Douglas W. Stoddard MD, M Sport Med, Dip Sport Med, ES
Medical Director-Toronto Sports & Exercise Medicine Institute (SEMI)
Medical Director-Medion Corporation (eload, EMEND, Zone Caps)
"Stomach and intestinal distress are quite common in the cycling world. The following is a summary of common symptoms, causes, prevention and treatment.
Symptoms
Many of you have experienced the nausea, cramping, bloating, pain and diarrhea that can accompany this syndrome. These symptoms are the ones directly related to your gastrointestinal tract malfunctioning, and therefore I will call these “primary” symptoms. The symptoms which you may not attribute to gastrointestinal (GI) tract dysfunction, but that can be very much related, are bonking (low blood sugar), muscle cramping, muscle burning and dizziness, all potentially contributing to reduced performance. These symptoms I will call “secondary” symptoms. Secondary symptoms can be indirectly related to GI tract dysfunction through malabsorption, where your stomach and intestines are not adequately digesting and absorbing the fluid and nutrients required to sustain performance. Therefore, your stomach/intestines play a huge role in optimizing (or not) your training and competing.
Causes
Several causes for digestive system dysfunction in the cyclist exist.
Blood Flow
“Blood flow” causes stem from the fact that the stomach and intestines (and other “digestive” organs like the pancreas, gall bladder and liver) require a certain amount of blood flow to function optimally. During exercise, blood flow is shunted away from your digestive system in order to supply your muscles with oxygen/energy, to remove waste products of metabolism from your muscles, and to supply your skin with blood to aid in cooling/sweating. The gastrointestinal tract is not generally forced to digest and absorb fluid/nutrients with so little blood flow, which is a big reason athletes working hard run into trouble. Bear in mind that the more intense you are working (the higher your percentage of VO2 max), the more these symptoms can be a problem, once again due to progressively decreasing GI tract blood flow. The length of the event is also important (longer equals higher chance of symptoms, likely related to extended reductions in blood flow to the organs of the digestive system). Finally, the mechanical compression exerted on your abdominal region resulting from the forward position cyclists often adopt may also play a role in impairing blood flow to your GI tract.
Prevention of blood flow related GI tract dysfunction means you must train your stomach and intestines to work with less blood. This means during training, drink and eat as if you were in a race. Secondly, you may have to slow down or stand down during a race, reducing the blood required in your muscles and skin, and allowing more blood to flow to flow to your gut. This can help reverse what may seem like a very “uncooperative” digestive system. Finally, I advise cyclists to sit up for 30-60 seconds, out of the forward position, at least once every 15-20 minutes, especially if you are GI tract sensitive, if the race format permits.
Anxiety
Anxiety and nervousness have an incredible effect on the digestive system, as nervous impulses can alter the way your stomach and intestines work, often leading to the primary symptoms of nausea, cramping, bloating, pain and diarrhea. Also, various hormones secreted in response to exercise and anxiety, such as adrenalin, can also have a negative effect on the GI tract. Most cyclists have had at least one episode of loose stools/diarrhea prior to a race, which is attributable to these nervous/hormonal factors.
Prevention of anxiety related GI tract dysfunction is obvious-understandably, controlling race anxiety is easier said then done. However, if this seems to be a big problem for you, get some help. Sport Psychologists can help teach you to control, and harness, all of that nervous energy, and use it to your advantage.
Anxiety explains the common complaint heard in Sports Medicine offices around the world that “everything seemed fine in training, but my gut just shut down during the race”. Assuming that your nutritional plan did not change compared to training, anxiety may well have been the culprit. Never underestimate the power of anxiety and its role in shutting down your digestive system when the “stakes” appear to be high.
Carbohydrate Source and Concentration
Your choice and concentration of carbs ingested can play a dramatic role in the functioning of your GI tract. Fructose, or fruit sugar, is a sweet sugar found in many sports nutritional products. It also happens to be a well known irritant to the stomach and intestines. Gut troubled athletes should not ingest this sugar during training/competition. Natural sources of fructose include bananas and other fruits-these should also be avoided.
Additional potential problems with carbohydrates include ‘resistant starch’, which is long chain carbohydrates that escape full digestion, and pass into your large intestine, where they can cause bloating, flatulence, nausea and diarrhea. This process will also contribute to dehydration, as these carbohydrate remnants pull water into the large intestine with them, reducing available water for absorption into your body. The more longer chain carbohydrates you ingest, the more this can play a role. Examples of such carbohydrates are maltodextrins, amylopectin starches and amylose. All gels contain high concentrations of these carbohydrates, and can contribute to this phenomenon. Gels, however, have to be made out of these types of carbohydrates for a variety of reasons, so you may not have much choice here but to experiment between different manufacturers re finding the one that is suited to you. Sports drinks, however, do not have to be made of these long chain carbohydrates, and better choices for sports drinks are the short chain carbohydrates, like dextrose, which is not resistant to digestion.
Concentration of carbohydrates ingested is also important. All gels have a whopping concentration of carbohydrates in them, and highly concentrated carbohydrate substances like these can be very irritating to GI tract. Ingesting your gels with some of your sports drink, or small amounts of water, can help dilute them in your stomach and hopefully reduce this potential irritation.
Also, your sports drink should have no more than a 6% solution of carbohydrate in it (some have up to 8%). Basically, this means a maximum of 60 grams carbohydrate/liter. Higher percentages of carbohydrates can contribute to GI tract disturbances.
Too Much “Stuff” In Your Sports Drink
The more “stuff” packed into a drink, the more potential for irritation. This is due to a concept called osmolarity, and its close cousin, osmolality. Both of these concepts involve the number of particles (atoms and/or molecules) dissolved in a solution. The more particles in a solution, the higher the osmolarity/osmolality, and the more potentially irritating to the gut. Some companies are trying to make their drinks the answer to everyone’s nutritional needs, manufacturing drinks containing everything from protein to chromium. A sports drink used during training and competition should be as “clean” as possible, supplying the necessary essentials of carbohydrate, electrolytes, water and lactic acid buffers ONLY. Adding more than this adds more potential for gut irritation as your stomach and intestines are forced to contend with non-essential ingredients. Sure, you need protein, and trace minerals like chromium, as well as a whole host of other things, for optimal health. However, the time to ingest these is not during training/competition, especially if you are gut sensitive-your post race/daily diet needs to supply all of these other nutrients. Save your gastrointestinal tract during training, and especially racing, for only those things that are absolutely necessary for optimal racing.
The “Empty Stomach” Syndrome
This syndrome results from not having at least a partially filled stomach at all times during your race. Gastric (stomach) emptying decreases exponentially as the volume of stomach contents decreases. Therefore, you must maintain your gastric volume i.e. always have something in your stomach. Again, this underscores the importance of training with food and fluids. Start your race with something in your stomach, and make sure you keep it “topped up” with relevant fluid and food throughout the race.
Lactic Acid Buildup
It is well established that gastric emptying is reduced with rising lactic acid levels. Lactic acid is a product of glycolytic anaerobic metabolism (glucose metabolism without oxygen), and more is produced as your exertion level rises closer to VO2max. Cyclists are very familiar with the concept of anaerobic threshold, and crossing this threshold dramatically increases lactic acid output. This must be controlled, and substances ingested that buffer lactic acid, such as MultiCitrateä, are helpful. Also, stemming the production of lactic acid is also important, and this ties into the concept of selectively reducing your exertion level when possible to allow for breaks in lactic acid production and increases in lactic acid clearance from the blood.
Ingesting Caffeine
Ingesting caffeine containing substances may contribute to your GI tract problems, as caffeine helps induce relaxation of your gastroesophageal sphincter (the valve between your esophagus and stomach) which can contribute to heartburn and stomach pain. Many sports nutritional products contain caffeine, presumably for its stimulatory effect and effect on free fatty acid metabolism (it should also be noted that caffeine may also have an inhibitory effect on carbohydrate metabolism-probably not good for endurance athletes). Again, if you are stomach sensitive, you may need to avoid caffeine, both in your daily diet, and during training/competition.
Dehydration, Electrolyte Depletion and Bonking
Failure to maintain adequate hydration, electrolyte and blood sugar levels all can contribute to GI tract shutdown, and GI tract shutdown can contribute to dehydration, electrolyte depletion and bonking…thus, a vicious cycle develops, and this cycle has ruined many races for many individuals. The gastrointestinal tract is highly dependant on normal hydration, electrolyte (especially sodium and potassium) and glucose levels for optimal function. Falling hydration, electrolyte and glucose levels only increase the risk of GI tract shutdown. Once in this state, it is difficult, if not impossible, to digest and absorb necessary fluid and nutrients to fuel your performance-bloating, nausea, flatulence and diarrhea usually result. Ask yourself: “Am I replacing what I am losing?” Bear in mind that your sweat has an average of 700-1100 mg of Sodium/liter, and 180-315 mg of potassium/liter. Most sports drinks contain a maximum of 1/3-1/2 of these values. If you are not sure, consult a good Sports Medicine Doctor, Sports Dietician or Naturopath who has an interest in endurance athletics.
Medical Causes of GI Tract Shutdown
While the above causes may be applicable to you, you may have other, more “medical” reasons for your gut problems. Seeing a good Sports Medicine doctor is the best place to start. Various conditions like reflux esophagitis, ulcers, gastritis, dysmotility syndromes and gallstones can all cause primary and secondary GI tract symptoms. All are treatable, once diagnosed.
How do you know when to see your doctor? Simply, if you have symptoms outside of exercising times, or, if you have tried incorporating the suggestions above during exercise, and you are still struggling.
In Conclusion…
Primary and secondary symptoms of GI tract dysfunction are not uncommon in cyclists. My advice is to do your best to prevent this syndrome from even starting, using the above tips, as once symptoms of this syndrome start, they are often difficult to stop!"
