Excessive amounts of exercise are linked to a higher risk of acute or chronic gut issues, a new study has found, cautioning that over-exercising can trigger your intestinal cells to become injured and leaky, especially if you've got a gut-related medical problem already.
Researchers say a moderately intense workout of 2 or more hours is enough to push the risk of damaging your gut higher, but add that people who already have bowel conditions should not be afraid to participate in "low to moderate" exercise.
According to a new meta-review of previous studies on exercise and gut health, a team from Monash University and the University of Tasmania in Australia has found that too much exercise can trigger cells in the intestines to leak toxins.
Those toxins then seep into the bloodstream, potentially causing a variety of health issues that can be exacerbated if you're exercising in hot conditions.
But the researchers have also found ways to limit the damage.
The review looked at 62 previous studies from the last 20 years, covering activities such as running, cycling, and resistance exercise, and identified the exact point in the exercise where gut damage started to take effect.
"Exercise stress of 2 or more hours at 60 percent VO2 max [the level of oxygen consumption] appeared to be the threshold whereby significant gut disturbances arise, irrespective of an individual's fitness status," the team writes in a press statement.
Some prevention strategies did seem to limit the damage: staying hydrated, taking on carbohydrates during exercise, and avoiding anti-inflammatory drugs were all found to reduce some of the health risks in some cases.
These counter-measures weren't particularly clear-cut though, and the team suggests further research to get a better idea of how they affect our bodies.
Before you pack away the exercise bike, the scientists still reaffirm that exercise is incredibly good for you, but they do warn against overdoing it, especially if you've got a gut-related medical problem already.
"It is recommended that a full gut assessment during exercise should be undertaken by individuals with symptoms of gut disturbances during exercise, to ascertain what is causing the issue and to develop individually tailored management strategies," says one of the researchers, Ricardo Costa from Monash University.
In short, the team advises tailoring your exercise regime to your own body, an idea that's backed up by previous studies.
More generally speaking, the dangers of overdoing it with exercise are well documented. A small 2015 study found that the mortality rate of people who overdid their jogging regime didn't differ too much from those who didn't do any jogging at all.
Meanwhile, a study of mice in 2014 found that endurance exercise could interfere with the natural rhythm of the heart.
But what everyone agrees on is that the benefits of regular exercise do outweigh the potential risks: it keeps your weight down, strengthens your bones and muscles, boosts your mood, increases your chances of living longer, and reduces the risk of many health problems, including heart disease, diabetes, and some cancers.
Just make sure you know how much exercise is enough for your body.
The findings have been published in Alimentary Pharmacology & Therapeutics.