CYCLING PERFORMANCE TIPS

The Athlete and the GI Tract

• 150 participants (74 men and 76 women)
• walking 164 - 203 km over 4 days
• 24 % had nausea, headache and flatulence
• 2 stopped the walk due to GI symptoms
• Conclusion: GI symptoms during long distance walking can impair exercise performance although these occur less frequently and are less severe in comparison with prolonged intense exercise.

• Heartburn
• Chest pain
Bloating
• Belching
• Nausea
• Vomiting
• Abdominal cramps
• Side ache
• Flatulence
• Diarrhea

With running, lower GI symptoms (cramps, diarrhea, and rectal urgency) are more common than upper (nausea), with rectal urgency being the most common symptom in up to 63% of regular runners followed by diarrhea in 54%.

Modifiers of GI Symptoms

1. The presence of symptoms in the non exercise period - if the athlete has irritable bowel syndrome before they begin to exercise regularly, they will probably have more symptoms afterwards.
2. Age
   • younger athletes have more symptoms than older ones (2 studies)
3. Gender
   • GI symptoms are slightly more common in women (2 studies)
   • most felt symptoms they were unrelated to their menstrual cycle
4. Diet - this is important because of the many, varied approaches (eating and supplements) used by athletes to give them "that extra edge".
   • there is a reported increase in reflux and upper abd symptoms with the pre exercise ingestion of:
     • too big a meal too close to exercise
     • fats
     • hypertonic drinks - glucose syrups - honey/maple syrup
     • foods high in dietary fiber (a problem for vegetarians)
     • high protein diets
   • supplements taken during exercise
     • study of 3 drinks (water placebo, sports drink, semisolid feeding) in 32 triathletes exercising 3 hours at 75% VO2max. Cross over study with each subject trying each in 3 trials of alternating running and cycling.
     • 4/32 had to stop in each "arm" from GI symptoms (there was no "best supplement").
5. Training Status Less trained individuals have more symptoms. The gut does not adapting with the stress of progressive training. But, training will help prevent GI symptoms. An example of indirect adaptation. May be tied into the next one:
6. Intensity of exercise(3 of 5 studies showed a correlation). Especially in runners, symptoms seem most likely to occur after an episode of particularly severe exertion OR during a period of rapid increase in training mileage.
7. Mode of exercise
   • symptoms are more common with running than cycling
   • with running, lower GI symptoms are twice as common as upper (84 versus 44 %), and in triathlons, most lower GI symptoms are during the run segment
   • cyclists have (relatively) more upper GI symptoms that runners (bent over position?)
   • events with a relatively stable body position
     • swimming
     • speed skating
     • cross country skiing
     have fewer symptoms than running - mechanical effects on the viscera?
8. Duration of exercise - symptoms are more common the longer the event (marathon for example)
9. Hydration status

   80% of marathoners with a 4% weight loss have GI symptoms

   • If one gets dehydrated, blood viscosity can change
   • Symptoms increase when decrease in body weight is 3.5 to 4 %
   Controlled dehydration in a sauna with a set exercise regimen - with dehydration significant slowing of gastric emptying and increase in nausea for a set amount of exercise.

10. Certain non dietary supplements/meds
    • caffeine
    • herb extracts
    • salt tablets

    
    
    Next we'll talk about the most common exercise related GI system disorders.

    • Gastroesophageal Reflux/Chest Pain
    • Diarrhea
    • GI bleeding
      
      
      
      Next section - Most Common Exercise Related Gastrointestinal System Disorders
      

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