Stomach Issues in the Heat, Renegade Endurance Radio Episode 40
Most athletes are no strangers to stomach issues during training and racing. But why is it that when it gets hot, things seem to get worse? I dove into the research to find out what science says about stomach issues in the heat and I talk about what you can do to decrease your risk of having GI distress while training or racing in the heat.
summary of recommendations to combat heat related stomach issues
If you are planning on racing in an environment that is warmer than you are used to, it’s a good idea to become acclimated to exerting yourself in the heat.
Go to a hot place and train
Turn your not so hot place into a hot place and train (heaters, close the windows, wear more clothes, etc.)
Avoid NSAIDs at least 24 hours prior to hard exercise in the heat
Avoid high-fructose foods. Interestingly, a combination of fructose and glucose might be ok and better tolearated.
Avoid drinks with very high concentrations of carbohydrate to prevent high osmolalties in the stomach
Ingest carbs with sufficient water to prevent high osmolalities in the stomach
If you use gels, you absolutely need to be drinking plain water with them. The same goes for any high carb food you might eat during a race. That doesn’t mean that you need to avoid sports drinks, but after doing this research, I’d say it means avoiding sports drink intake immediately surrounding high carb food intake IF you are using something other than your sports drink for fuel.
Practice your nutrition - athletes who are not used to fluid and food ingestion during exercise have double the risk of developing GI symptoms compared to athletes who are used to eating and drinking during exercise.
This goes for trying a variety of foods too because you can train yourself to ingest real foods vs. high sugar/carb gels, etc.
Consider supplementation with l-arginine if you are going to be training or racing in heat. Most of the information I found on this recommendation is in other animals (not humans - mice, pigs, and chickens). All of the studies I read showed that the amount of bacterial translocation (which is a sign of increased intestinal permeability) that occurs during exercise under heat stress is greatly reduced with l-arginine supplementation.
As with any supplement, be sure to talk with your healthcare provider before starting a new supplement.
One of the potential side effects is diarrhea if taken on an empty stomach, so if you go this route, definitely experiment with it during training before you try it in a race!
Dosage should be about 500mg and studies seem to agree that there are very few adverse effects when taking less than 20g per day or less.