Why Fitter, Lighter Runners Experience Less Stomach Discomfort on the Run

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Running has many advantages over other fitness activities. It requires less gear than most, it can be done just about anywhere, and nearly everyone knows how to do it. But on the negative side of the ledger, running causes more gastrointestinal symptoms (bloating, flatulence, etc.) than do cycling, swimming and other fitness endeavors. Running-related GI problems are especially common among women: A new study shows just how common, while also providing helpful information about how to avoid and overcome these nuisances.

Dutch researchers surveyed 433 women training for 5K and 10K events. Nearly half of the respondents reported experiencing at least one GI symptom on their most recent run, and 40 percent said they had such issues generally when they ran. The most common complaints were side aches (16 percent), flatulence (15 percent), needing to use the bathroom (13 percent) and belching/regurgitation (11 percent).

More: Soothe Runner's Trots: What to Eat and Drink

The most common predictor of GI troubles in the subjects' most recent run was a history of such symptoms. This finding confirms evidence from previous studies indicating that some people are naturally prone to GI distress during running while others are not.

Interestingly, the timing of the last meal or snack consumed before running appeared to have no effect on the risk of GI symptoms, although few subjects ate closer than 90 minutes to the start of their runs.

More: Active Cookbook: The Best Pre- and Post-Run Snacks

So what can you do to avoid discomfort? The results of the survey offer four practical takeaways.

Be Patient

"Ignore the problem," is seldom good advice, but where running-related GI problems are concerned, it just might be. The authors of the new study reported that women who had been running longer than one year were significantly less likely to experience symptoms than were those who had taken up running within the past year.

More: When Does Running Get Eaiser for Beginners?

There was also an association between age and the incidence of GI complaints, with older women experiencing them less often. Previous studies have made the same observation. The reason may be that oxygen supply to the intestines during exercise improves with age. In any case, you can expect your running-related GI troubles to become milder and less frequent as you gain running experience and graduate from one age group to the next.