Interesting article about runners gut

[Yesletsgo]

This article from the New York Times has some interesting information about runners gut, why it happens and how to avoid it. There's a paywall but I think they allow you to read a few articles before you have to sign up.

nytimes.com/2022/10/04/well...

[dijep Graduate10]

Well it looked interesting but after signing in for limited free access it immediately said I'd reaced my limit ..... very annoying. I know I've read articles on their site before so I guess that's why.

[Yesletsgo Ambassador Graduate10 in reply to dijep]

Thankfully Nowster has copied it below

[Oldfloss Administrator 60minGraduate]

Always good to have more info !

[nowster Graduate10]

Save page source, open in LibreOffice. Text revealed:

What causes this, and what can I do to prevent it?

For many runners, long or intense bouts of exercise can lead to a range of digestive issues, like stomach pain, nausea and diarrhea. While gut issues can happen during many endurance sports, experts say they can be especially problematic for runners and are thought to be caused, in part, by a lack of blood flow to the intestines. Some call it runner’s gut, others refer to it as runner’s belly, runner’s trots or a number of other names.

So what is runner’s gut, exactly? And what can be done to avoid it?

What causes runner’s gut?

During a run, when oxygen is supplied to skeletal muscles, “the blood that is supposed to be flowing to the intestines is actually going to your muscles,” said Sam Wu, an exercise scientist at Swinburne University of Technology in Melbourne, Australia.

This shunting of blood to the muscles can negatively affect digestion, as “you need a lot of blood flow to the gut when you are digesting food,” said Dr. Lauren Borowski, a sports medicine physician at NYU Langone Health.

This reduced blood flow, combined with physical jostling, can cause nausea, diarrhea, cramping or the sudden need to defecate, especially if you are running on a full stomach, Dr. Borowski said. Such symptoms can be exacerbated if a person is dehydrated, which reduces the overall volume of blood flowing through the body, or if they have hard-to-digest foods moving through the digestive tract, such as complex carbohydrates, fiber or protein. Without enough blood to aid digestion, the body will pass partially or incompletely digested foods.

“Things that are not digested are just flowing through your intestines,” Dr. Wu said. “That’s why you have to run to the toilet.”

For long, sustained endurance efforts, such as running a marathon, the shunting of blood away from the intestines can damage the thin layer of epithelial cells lining the intestine, which control what enters the bloodstream. During a long run, a sustained lack of blood flow can cause these cells to detach from each other and burst open, spilling their contents into the bloodstream.

The idea of intestinal damage may sound worrying, but “for most people, that damage is transient,” said Kate Edwards, a doctoral student at the University of Tasmania who researches gastrointestinal symptoms in endurance athletes.

However, Dr. Wu noted, it’s likely that this intestinal damage can affect the way nutrients are absorbed during a race, leading to less available energy, or cause general gut discomfort. In a small study published in 2021, researchers from Britain found that runners who collapsed during a marathon tended to have higher blood levels of a marker for intestinal damage than those who did not collapse, suggesting that gut issues may have contributed to their collapse.

As Ms. Edwards and her colleagues demonstrated in a separate small study published last year, intestinal damage can be correlated with the intensity of exercise and isn’t specific to running. When compared with runners, cyclists showed similar levels of damage when exercising at similar intensity levels, although they reported fewer overall symptoms of gut discomfort. This damage mostly occurs during high-intensity efforts, Ms. Edwards said, when exercisers were working out at 80 percent of the their bodies’ VO2 max (a measurement of the ability to absorb and use oxygen, loosely tied to effort), compared with when they were working at 60 percent.

“Anything below a moderate intensity, it’s unlikely you are going to get much damage,” Ms. Edwards said.

How to avoid it

Thankfully, there are ways to avoid runner’s gut, Dr. Borowski said. When running long distances, such as when training for a marathon, you need to eat enough to fuel your body, but not so much that it causes gut issues, which is tricky. “What to eat and when to eat is really difficult when it comes to marathon training,” she said.

Two to three hours before a run, eat foods that contain simple carbohydrates, like bananas, rather than foods with lots of fiber or complex carbohydrates, such as berries or whole wheat bread.

Training the gut for a long run can be every bit as important as training your legs. Practice what to eat and drink while training, and remember that a race will be more intense than most training runs. Pay special attention to how you feel during training runs done at race pace, rather than just during long, slow runs. On race day, anxiety can also contribute to stomach issues, which is why Dr. Borowski advised not putting any extra strain on your gut and to stick with the usual foods you eat before runs, rather than trying something different. It’s also important to stay hydrated.

One recent study of 46 people concluded that compression socks may help, too. In the study, published in September in the Journal of Strength and Conditioning Research, researchers from Australia looked at the associations between wearing compression socks and intestinal damage during a marathon. Compression socks, which apply pressure to the outermost muscles of the legs, are known to improve circulation.

In the study, those who wore compression socks while running a marathon showed lower levels of a blood marker for intestinal damage than those who did not. Wearing compression socks may not thwart runner’s gut, Dr. Wu said, but it is a relatively simple action that may help minimize the effects.

“If we can improve the blood flow and increase circulation to the deeper parts of the body, then we should be able to promote blood flow back into our digestive system,” said Dr. Wu, who was one of the study authors. “That can help to decrease or reduce the amount of damage that’s done to our gut during high-intensity exercise.”

Rachel Fairbank is a freelance science writer based in Texas.

[Yesletsgo Ambassador Graduate10 in reply to nowster]

Thanks @nowster, I hate paywalls but there's currently a £2 per month offer for a year on the NYT so I treated myself. I may save your instructions for getting round them for later use