The link between stress and gut health isn’t anything new. It’s a well-established fact that physical stress like intense endurance workouts can lead to something called “runners gut”, showing the digestive impact of overloading our bodies. And we know that the so-called happy hormone serotonin is made in the gut, meaning a well-fed digestive tract can help us feel more positive.
As someone who has been diagnosed with IBS and has a sensitive (bordering on dramatic) gut, I’ve come to expect flare-ups during physical and mentally stressful times. But I recently found out that the link goes deeper than just diet and movement and lies in a mighty, dome-shaped muscle: the diaphragm.
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What is the diaphragm?
“The diaphragm is a big muscle that separates our chest and lung cavity from our abdominal cavity – the gut. It wraps from one side of the ribcage to the other, and is one of the key structures involved with our breathing,” says osteopath Maarten Becue from OsteoAllies.
“When breathing out, the diaphragm acts as a lever, increasing the pressure around the lungs to push the carbon dioxide and waste product out. When we breathe in, our diaphragm moves down to allow the lungs to expand and oxygen to come in. They can move an average of around one to two and a half centimetres in “quiet breathing”. In athletes who are forcibly inhaling large amounts, the diaphragm can move up to 10 centimetres,” he adds.
That movement, and the change of pressure it creates in the abdominal cavity, is also crucial for our digestion. When the diaphragm moves down, it massages the gut contents, easing the transition of food through the digestive tract. It also stops acid and fluid from coming back up, Becue explains. “Think about how water flows to the top if you squeeze a plastic bottle – fluids will always move to the area with the least pressure.”
With all that in mind, we can get digestive issues when the diaphragm isn’t working as it should. “When the diaphragm is restricted, because the muscle is tight or not expanding properly, the changes it makes to the cavity pressure will not be optimal for digestion,” Becue explains. “It can change how fluid and solids move through the gut, and it may increase gut-related symptoms such as constipation, bloating, cramps, diarrhoea or acid reflux.”
In a 2018 paper published in Cureus, researchers noted that the diaphragm muscle is the only skeletal tissue whose movement affects both the small and large bowel. They reported IBS patients often having a lack of motor coordination between the diaphragm and the abdominal wall and link GERD (gastroesophageal reflux) – which impacts up to 40% of people with IBS – to diaphragmatic dysfunction.
That kind of dysfunction is “one of the most common osteopathic findings in people who have gut-related conditions”, according to Becue.
How does diaphragm restriction or dysfunction happen?
You guessed it: stress. Have you ever noticed yourself holding your breath or taking shallow breaths into your chest when you’re feeling overwhelmed? Those short intakes of air mean that the diaphragm doesn’t rise and fall as it should and leads to gut problems, says Becue.
Intense exercise can also put pressure around the ribcage, chest and back – if you feel tight in those areas after training, you may also be tight in the diaphragm that sits beneath them.
“Diaphragm restrictions may be a result of musculoskeletal pathologies like osteoporosis and scoliosis, as these bring complications to rib and diaphragm mobility and impact gut health,” Becue adds.
How to improve diaphragm health
Becue says osteopaths can use hands-on treatment to release the tightness in the diaphragm, just as they can with any other muscle group. But if you don’t want someone gripping your rib cage, then there are at-home remedies too.
“The most accessible way to mobilise the diaphragm is through belly breathing,” says Becue. That means letting the stomach expand as you inhale and fall as you exhale. It sounds like something that should just happen, but when Becue asked me to try I realised that my chest and ribs could easily expand but my belly barely moved.
He recommended that those who have lost the natural art of belly breathing spend a few minutes every morning and evening practising conscious belly breathing until it becomes subconscious. I’ve also made sure that, when noticing feelings of overwhelm creep into my mind, I begin to think more about where my belly button is.
It’s too early to tell if it’s helping, but even those small moments of noticing my breath do make me feel a little less stressed – and we know that’s one of the best ways to stop IBS in its tracks.