Dr. Jeff Sankoff answers your tri-training questions
Dr. Sankoff,
I am a 55-year-old male who has been a runner for 30-plus years and has been doing triathlons for the past eight years. I have done up to full distance Ironman events. I have noticed I often have trouble on the run with upset stomach to the point where I even have to walk. It seems to occur more often during events in warmer temps. I have also noticed that the next day my voice is affected (I can hardly speak).
As I'm currently preparing for Ironman Arizona, in April, I was wondering if these symptoms sound familiar and if you have any thoughts on what could be causing it?
Thanks in advance for any advice you can provide.
Jeff Summy
The short answer: The effects of intense exercise on the gastrointestinal (GI) system vary from individual to individual and are in part related to environmental factors. Recognizing the symptoms of exercise-induced gastrointestinal distress may help you adapt and minimize their effects on your performance.
The long answer: Exercise physiologists and sports physicians have long known that runners and other athletes have a high prevalence of GI symptoms associated with exercise. These include upper-tract symptoms; such as increased eructation (belching), abdominal pain, nausea, vomiting and lower tract symptoms; like the urge to defecate, abdominal cramping and increased flatulence. Symptoms are more pronounced during hard runs, in warmer weather and during longer races – all of which can predispose to becoming dehydrated, an important factor for all causes of abdominal pain.
The most common GI symptoms experienced by endurance athletes include: gastroesophageal reflux, or heartburn, delayed gastric emptying, intestinal bloating and flatulence, and diarrhea. Each may be experienced during any leg of a triathlon but all are more common during the run segment as this occurs later in the race and is physiologically the most demanding of the three activities. I will consider each in turn.
Gastroesophageal reflux (GER): Distance runners frequently suffer from heartburn during training or racing. Unfortunately, little research has been directed toward this problem.
The esophagus is a muscular tube with a sphincter at the lower end. Normally, contractions of the muscles in the wall of the esophagus ensure that whatever we swallow moves down toward the stomach. Contraction of the sphincter then prevents gastric contents from coming back up. During exercise, both of these processes can be impaired by the increase in intra-abdominal pressure, which can result in the reflux of acidic stomach contents into the esophagus.
There are few effective remedies for this common problem. The most important step that sufferers can take is to avoid the things that are known to relax the lower esophageal sphincter. These include caffeine, alcohol and smoking. The use of chewable antacids or over the counter acid reducing medication may provide some relief. However, I cannot recommend either of these as no studies have ever been done to address their efficacy or side-effects during exercise. For the most part, exercise induced GER causes only mild, self-limited symptoms, and is not known to cause any long-term problems.
Delayed gastric emptying (DGE): The importance of ingesting an adequate amount of fluids, electrolytes and energy sources during prolonged periods of exercise is well understood by most athletes. Unfortunately, not everything that is swallowed is subsequently absorbed by the body -- particularly when an athlete is exercising at greater than 70 percent of his or her max heart rate. Such a scenario may lead to a feeling of fullness and bloating and may even cause nausea and vomiting. More importantly, as less fluid is delivered to the intestines dehydration can ensue. As an athlete becomes dehydrated he or she experiences a further decrease in gastric emptying, which can escalate the dehydration cycle. In addition, environmental conditions such as high heat and humidity can negatively affect the rate of gastric emptying and promote even more rapid dehydration.
DGE can have significant consequences and negatively impact performance. Unfortunately, there is no way to completely prevent this, nor is there any rapidly effective treatment. The best preventive measure is to ingest a balance of high- and low-energy fluids (i.e. a mixture of water and sports drinks), to keep the concentration of sugars from getting too high.
Once DGE becomes apparent, the only viable remedy is to decrease the effort of exertion to a level below 70 percent of aerobic capacity and avoid high-carb sports drinks in favor of plain water. This should restore a more normal rate of gastric emptying. Once the symptoms have abated, a trial of higher levels of exertion may be undertaken, but pay careful attention to fluid intake.
Intestinal bloating and flatulence: There are two reasons for this: Swallowing air and ingesting a high concentration of simple sugars. The former is more commonly seen in triathletes than in cyclists or runners. This is because air ingestion occurs most commonly during swimming. Once in the stomach, air can be expelled through belching or will be passed to the intestines for passage through the colon. Significant quantities of air in the bowels cause uncomfortable bloating and cramping. The best way to avoid this problem is to minimize air swallowing during swimming and encourage belching to expel any air that is ingested.
Simple sugars in high concentrations may not be completely absorbed. After passing through the small intestine they reach the large bowel where they become substrate for the bacteria normally living there. When these bacteria digest the sugars, they produce varying quantities of gas as a natural by-product. This too can cause uncomfortable bloating and cramping. The best way to avoid this problem is to minimize the concentration and amount of simple sugars ingested.
Diarrhea: A final common problem encountered by many endurance athletes is diarrhea. The most common causes relate to fluid shifts and decreased absorption.
Drinking large amounts of fluids highly concentrated with simple sugars may cause fluid to be drawn from the bloodstream and into the intestines. This speeds up intestinal transit, resulting in diarrhea that may be severe and may then lead to dehydration. Once again, the best preventive measure is to ingest a lower volume of simple-sugar-containing fluids and increase water intake.
A final potential cause of abdominal pain relates to decreased blood flow to the intestines. This only occurs in athletes who have become dangerously dehydrated. As activity continues, blood flow to the muscles continues at high levels. If the amount of total body water has fallen to low, there may be insufficient blood volume to perfuse the intestines as well. As a result, the intestines see a drop in oxygen delivery and painful ischemia may result. This is a potentially dangerous situation that may be easily avoided simply by maintaining adequate hydration.
With respect to the symptoms that have plagued Jeff, I suspect he has suffered for the most part from DGE. Unfortunately, no amount of training can prevent these problems, and Jeff will merely have to learn what to do should these symptoms occur again in the future. DGE may be dealt with by increasing the intake of water, decreasing the intake of sports drinks and by a period of diminished level of exertion.
As for the effects on his speech the next day, I believe that this is an unrelated issue. The most likely cause of this is transient laryngitis brought on by breathing dry air through the mouth over the course of the long race. Nose breathing may help lessen this problem but is unlikely to be a viable solution. Transient laryngitis is self-limited and carries with it no serious complications – a minor irritation after a hard day’s work. I suppose Jeff’s race stories will have to wait until he recovers!
Train hard, train healthy,
Dr. Jeff Sankoff
Dr. Jeffrey Sankoff, MD, FRCP(C), is a two-time Ironman triathlete and ER physician based in Denver, Colorado. To learn more, visit Sankoff’s Web site.
If you have a question for Dr. Sankoff, please e-mail feedback@triathletemag.com Triathlete Magazine Interactive. Please include “Dr. Sankoff” in the subject line.