Put the palm of one hand on your chest and the palm of the other hand on your belly. Now take a breath but try to expand only your chest, so only the chest-hand moves outwards. What your doing is using your intercostal muscles to breathe. These are the muscles that run in between your ribs.
Now try another breath but this time try to expand only your belly, so that only your belly-hand moves outwards. This time you're using a muscle called your diaphragm. This is a thin muscle, shaped like a parachute, that lies right under your lungs. When it contracts (and flattens) it draws breath into the lungs, and when it relaxes (and expands) it pushes air back out of the lungs.
Diaphragmatic breathing is this second kind - the kind where you use your belly to breathe. In fact, it's because it feels like you're using your belly (rather than your chest) that it's often known as belly breathing or abdominal breathing.
The thing is, a growing number of studies are showing that diaphragmatic breathing is really beneficial for a range of physiological and mental health issues.
A Breathing RCT
A recent study, led by Xiao Ma of Beijing Normal University, ran a random controlled trial to test the effect of diaphragmatic breathing on stress and mood. Forty participants were assigned to either a breathing intervention group (BIG) or a control group (CG).
The breathing group received twenty sessions of guided diaphragmatic breathing over eight weeks. This took place every other day in a conference room at their place of work. Each session involved 15-minutes of rest followed by 15-minutes of diaphragmatic breathing. During resting period, participants were instructed to breathe normally while they sat comfortably with their eyes closed. Then, during the diaphragmatic breathing period, they were instructed to inhale as deeply as they could while their belly expanded, and to exhale as slowly as they could while their belly contracted. They were also instructed to focus on their breathing and the sensations produced in the body.
Breathing, Stress and Mood
Whilst there were no significant differences between the BIG and CG participants at the start of the study, the participants who had been coached in diaphragmatic breathing showed a number of significant benefits by the end of the eight weeks.
Firstly, they reported experiencing significantly fewer negative emotions during the last week of the study. This dramatic drop in negative emotion was not found in the control group. Specifically, the breathing group were not reporting more positive mood, but rather the absence of negative mood.
Secondly, the diaphragmatic breathing resulted in a significant reduction in cortisol levels. This hormone is released when the HPA axis is activated - that's a neuroendocrine system in the body which is activated in response to chronic stress. Cortisol levels, therefore, are a reliable biological marker for chronic stress.
Given the cost and side-effects associated with anti-depressants, along with the relative ease of carrying out regular breathing exercises, it's no wonder that there is increasing interest in breathing as a treatment for depression and anxiety.