A powerful link between regular exercise and the gut microbiome which could change the way debilitating gut diseases such as Inflammatory Bowel Disease are treated has been identified in new research.
Researchers from ACU and Hudson Institute of Medical Research found that regular physical activity supported "cross-talk" between active skeletal muscles and gut microbiota to boost immunity.
The review, published in the journal Gastroenterology, shows skeletal muscles communicate with the gut to boost diversity in the microbiome and confer protection against many metabolic diseases.
Lead author Professor John Hawley, director of ACU's Mary Mackillop Institute for Health Research, said many studies have shown that regular exercise delivers numerous health benefits, but the mechanisms underlying these advantages were not well understood.
The review shows regular exercise changes the bacteria living in the gut which helps the body to fight illness and stay healthy.
Exercise and our gut microbiome – the trillions of microorganisms which live in the gut and play a vital role in our physical and mental health – are intimately linked.
So much so that the physical activity we do can improve the diversity of our microbiome, affecting our health and risk of disease.
"We now know that during exercise, the working muscles release small proteins into the blood which then circulate and 'communicate' with other organs and tissues," Professor Hawley, a leading exercise and nutrition expert, said.
"The exciting part is that we now realise that skeletal muscles don't just "talk" to fat and bone tissue, but they also communicate with the gut microbiome.
"I can't think of anything that exercise is not good for but the link between exercise and the gut microbiome is new and the more we find out about it, the more exciting it is."
Professor Hawley believes research into the muscle-gut axis will take off in the next decade, in the same way the link between the gut microbiome and brain health has.
The key to these connections is the release of "myokines" from contracting skeletal muscles, which create interorgan communication which, in turn, confers protection against numerous disease states.
Study co-author, paediatric gastroenterologist Associate Professor Edward Giles, said the new findings offer hope for the many people who suffer gut diseases, such as Inflammatory Bowel Disease.
"We know there is huge variation in the human gut microbiome, but it's equally true that reduced microbial diversity is a factor in several diseases of the gastrointestinal (GI) tract, systemic immune diseases, and cancers," he said.
"Physical activity boosts host immunity, facilitates a more diverse gut microbiome and functional metabolome, and plays a positive role in energy homeostasis and metabolic regulation."
However, there are limits to these benefits.
"Heat appears to be a limiting factor - beyond a certain temperature the body sends less blood to the muscles and any time there's this "fight for blood flow" the gut tends to lose out, so exercising in the heat is bad for GI disorders."
Working with Associate Professor Giles and microbiome specialist, Associate Professor Sam Forster, Professor Hawley now aims to further understand why exercise is so powerful in modifying the gut microbiome and possibly some of the diseases and conditions linked to the gut.
"We know the benefits of exercise are widespread, but we've recently discovered, for example, that athletes have greater diversity in their gut microbiome than the general population," he said.
"The exact amount and type of exercise required to induce favourable changes in the microbiome and enhance host immunity is currently unknown, but it's all relative; for people who are just beginning to exercise, the dose is probably quite small to induce beneficial alterations."
But the news is not all good.
"As soon as you stop training you start to lose some of the gut microbiome diversity, so the benefits are only maintained with regular exercise," Professor Hawley said.
"Of course, you have to take into consideration a person's diet in all of this and, as the saying goes, you can't outrun a bad diet.
"The bottom line is if you're not exercising, you should be. Will it have a beneficial effect on the gut microbiome? Absolutely. Will it have a beneficial effect on almost everything else? Absolutely."
