Your quads, hamstrings and calves all work hard to propel you forward when you run. But there's another muscle that’s also a real power player in your running: your diaphragm. With each forceful contraction, this key breathing muscle helps expand your lungs to bring in oxygen – which your muscles need to create energy – says Michael Jordan, director of research and education at Fast Track Sports Medicine and Performance Center in Fairfax, Virginia, US. You inhale the oxygen and exhale carbon dioxide, the buildup of which can cause anxiety and breathlessness.

Being aware of your breathing builds efficiency, a steadier pace and a calmer mind, even during high-pressure races, says pro runner and coach Neely Spence Gracey. If you focus on solid breathing,‘you’ll be able to push through fatigue and maintain form’, she says.

Learning how to breathe - the basics
Slow down and belly breathe

The most common reason new runners gasp for air is that they haven’t modified their ‘fight or flight’ response to ‘rest and digest’. This affects their heart and lungs to the extent that they can’t run without reaching their ventilatory threshold, the point at which you can’t breathe deeply or quickly enough to fulfil your body’s demand for oxygen, says running coach Erik Bies. Once you near this point, your body’s stress response kicks in, causing you to panic and struggle even more.

To avoid this, slow down at first. Stick to a pace that allows you to speak a few words
or sentences. Jordan recommends inhaling through your nose and exhaling through your mouth for the best gas exchange at an easy pace. With just a few weeks of training, your body adapts in ways that increase your ventilatory threshold – for instance, your muscles sprout new blood vessels, says Kyle Barnes, assistant professor of exercise science at Grand Valley State University, US.

Many new runners breathe from their chest instead of their diaphragm, limiting their oxygen intake. Combat this with belly breathing. Before you run, lie down and place your hand on your stomach. Take slow, deep breaths that lift your hand as you inhale and sink it as you exhale. Once comfortable on the ground, try belly breaths when walking, then while running.

Stop side stitch in it's tracks
Side stitches may occur when your diaphragm or another breathing muscle cramps up, often because you’re running too fast for your ventilatory threshold, says physical therapist Erik Bies. To stop one, try pursed-lip breathing: Slow down, pucker your lips and slowly exhale with force, as if you were blowing out candles. This helps your diaphragm relax. Eating a gel may help:electrolyte imbalances can make breathing muscles lock up.

Learning how to improve your breathing for intermediate runners
Focus and find rhythm

From there, it’s time to take focused breathing on the move with rhythmic patterns. Gracey recommends starting by inhaling for two counts, then exhaling for two, a pattern called 2:2 breathing. This will help you pace yourself better –the steadier you’re breathing, the less likely you are to go out too hard – and ensure a steady flow of oxygen to your muscles. Try it walking first, then on easy runs, beginning with one minute at a time every mile or two and gradually increasing the duration of your focus.

As you grow more comfortable with focused breathing, you can use it for faster runs, such as intervals and tempo. Paying attention to your breath can help you gauge your pace and tolerate the discomfort of speedy paces, so you can improve your ventilatory threshold even further, says Bies. Start by using 2:2 breathing during strides – 15-20-second bursts of faster running – or 30-second hill repeats, says Gracey. Eventually, you can extend the rhythm for longer intervals, such as faster half-mile or mile repetitions.

On easy runs, try 3:3 or 4:4 breathing, she says. Others recommend experimenting with a longer inhale than exhale– 2:1 for faster running, 4:3 or 3:2 for easier running – to see what feels natural. This may better distribute the impact across both sides of your body.

How to breathe like a professional
Count and train your diaphragm
During workouts and races, Gracey uses 2:2 breathing and mentally notes her strides. The first four-count inhalation and exhalation is one, the second is two, and so on. She counts from one to 100, then starts over again. ‘It gives me small goals to work towards,’ she says,‘and keeps me focused and present.’

Counting breaths proves especially useful in races with varying terrain, she says, because it’s harder to breathe on uphills and easier on downhills. Keeping your respiration steady rather than fretting about numbers on your watch ensures you’ll hit close to your goal pace.

While consistent running strengthens your breathing muscles, you can take them to boot camp for a bigger boost using a device such as OPUMP. ‘It’s like dumbbells for your diaphragm,’ saysBarnes. Start with two sets of 30 breath sat two different times of the day, using a resistance that’s challenging but that you can complete with good form. (Think:breathing from your belly, not shrugging your shoulders or straining your neck.)

You’ll probably see a difference within two to three weeks, or sooner. In one study, Barnes found runners improved their performance in a 3,200m time trial when they did 30 resisted breaths immediately beforehand as a warmup

Signs you're not using your diaphragm properly

Gasping is just one sign of poor breathing, saysJordan. Watch for these other red flags that may indicate not using your diaphragm efficiently:

Tightness or pain in your neck or back
Shoulders that rise and drop
Asymmetrical rotation in your torso
An arched back and flared ribs
Paradoxical breathing, when your stomach rises as you exhale and sinks when you inhale
How the experts measure diaphragm efficiency
How well can our bodies utilise the oxygen we breathe? According to the Journal
of Sports Medicine, here’s how the typical VO2 max measurements of marathoners stack up:

Elite marathoners: 67 to 85 ml/kg/min
Sub-3 hours marathoners: 65.5 ml/kg/min
3-plus-hour marathoners: 58.7 ml/kg/min