NEW YORK — Starting with the first reports of breathing difficulties among people who contracted Covid-19 and extending now to those wearing masks to limit the risk of acquiring or unwittingly transmitting the virus, the ability to breathe normally has become a common concern.

Some worry: Are we taking in enough oxygen to adequately supply our muscles, organs and especially our brains? (I’m among many who purchased a pulse oximeter to do daily checks of my blood’s oxygen level.) Are the masks we wear interfering with our breathing?

As I walk and cycle in my Brooklyn neighborhood, I see many people with masks under their chins who pull them over nose and mouth only when they’re about to pass another person.

Believe me, I understand and empathise. Walking around with half one’s face under layers of cloth, neoprene or some other protective covering is neither attractive nor comfortable, even more so now with summer heat approaching.

This is especially challenging for people who must wear masks throughout their workday, as well as those with pre-existing respiratory problems and people with poor hearing who now struggle to participate in mask-muffled conversations without the added assist of lip reading.

Alas, this is a fact of life we will most likely have to endure for many more months, perhaps even years, until an effective vaccine against this deadly virus can be developed and administered widely. There are ways, though, to maintain and even improve respiratory health while following the important guidelines for wearing masks issued by the Centers for Disease Control and Prevention to curb the spread of Covid-19.

But first, we could all benefit from a better understanding of a bodily function most of us have long taken for granted and learn how to maximise its efficiency and life-sustaining benefits. Based on the research I’ve done for this column, it’s apparent that even without a mask as an impediment, many people breathe in ways that compromise their well-being.

“Doctors who study breathing say that the vast majority of Americans do it inadequately,” Mr James Nestor, author of a new book, “Breath: The New Science of a Lost Art,” wrote recently in The Wall Street Journal.

“How we breathe matters,” he said, “and our attention to it is long overdue.”

For example, Mr Nestor noted, “nose breathing is better than mouth breathing” because it’s protective; the nose filters, heats and treats raw air.

“Inhaling through the nose stimulates the release of hormones and nitric oxide, which helps to regulate vital functions like blood pressure and increase oxygenation throughout the body,” Mr Nestor said in an email.

Given that most of us take about 25,000 breaths a day and breathing properly is critical to how well our bodies function, we should try to get the most benefit we can from this life-sustaining activity, with or without a mask.

So, in addition to Mr Nestor’s comprehensive treatise on breathing, I consulted an unusual expert, Mr Paul DiTuro, a former professional athlete and special forces medic in the US military who is now a performance breathing specialist for a company called PN Medical, which makes devices to help train respiratory muscles for people with conditions like emphysema as well as professional athletes.

Breathing done properly keeps the body in acid-base balance, which enables tissues to get the amount of oxygen they need to function optimally, Mr DiTuro explained.

This balance is achieved by maintaining an ideal level of carbon dioxide (CO2) in the blood. Too little CO2, which can happen when breathing is rapid and shallow, impedes the release of oxygen to body tissues and can cause anxiety, irritability, fatigue and lack of focus, Mr DiTuro said.

Rapid, shallow breathing keeps the body in a high state of alert and engages the sympathetic nervous system, an adaptation that is useful in times of danger but counterproductive to feeling calm and relaxed the rest of the time.

Even during normal times, many people breathe too fast and through their mouths, perhaps because of chronic stress or noses made stuffy by allergies or a deviated septum. I noticed that I tended to do the same when I was wearing a mask, and now consciously remind myself to breathe more slowly, inhale through my nose and exhale through my mouth, especially when I’m out exercising.

Without much effort, you can retrain how you breathe — with or without a mask — so that it is physiologically beneficial when you’re not being chased by a tiger.

Rapid breathing uses neck and chest muscles instead of the diaphragm, which is innervated by the vagus nerve responsible for calming the body. Mr DiTuro said, “Lack of diaphragmatic breathing makes it harder to mentally relax.”

Coincidentally, shortly before the pandemic struck, a physical therapist hoping to minimise back pain taught me diaphragmatic breathing, an ancient technique that quiets the body and mind by engaging the parasympathetic nervous system.

It’s widely used by opera singers, actors and meditators, among others. I was told to inhale through my nose and exhale slowly through my mouth. But instead of my chest expanding as my lungs fill when I inhale, my diaphragm — the dome-shaped muscle under my lungs — should contract and drop down toward my stomach.

Respiratory therapists teach diaphragmatic breathing to people with lung problems, and you can strengthen this important though neglected muscle on your own.

Lie on your back, knees bent, and breathe in slowly and deeply through your nose as your belly rises but your chest remains still. Then tighten your abdominal muscles and exhale through pursed lips.

Doing five minutes of respiratory muscle training every morning and every night can help you learn to breathe more effectively at all times without having to think about it. Having stronger respiratory muscles may also facilitate an effective battle against the coronavirus.

At the very least, they can make living healthfully through the Covid-19 pandemic while breathing through a mask less challenging.

A small investigative trial Mr DiTuro conducted with assistance from colleagues at the Mayo Clinic and other labs around the country suggests that over prolonged periods, N95 masks, the kind worn by doctors caring for virus-infected patients, “do have the potential to alter respiratory patterns enough to cause negative physical and mental effects.”

While more research on the possible effects of masks on breathing patterns is needed, Mr DiTuro suggests that in addition to respiratory training, some simple steps may help make wearing a mask easier.

Just before putting on your mask, take five “quality” breaths. With each breath, inhale through the nose for four seconds, exhale through the mouth for six seconds, then rest for two seconds. Repeat these five breaths as soon as you put on the mask, and again after you remove it.

If, for example, you are a teacher, medical worker or checkout clerk who must wear a mask for an extended period, take periodic breaks when you can safely remove the mask and breathe normally. THE NEW YORK TIMES