My first thought as I dove below the surface of the water was that I felt a little more peppy than usual, probably due to the extra pounds the quarantine brought with it. But as I kept gliding through the water, my initial worry about gaining weight was replaced by a feeling of catharsis, as if the water was cleaning me of the stress that had built up during the coronavirus pandemic. Stroke after stroke, I could feel my mood lift, my mind clear, and my body relax.

Thirty minutes later, I got out of the pool confident and calm, ready for the first of four night shifts in the intensive care unit. Usually I feared the first of those night shifts, but somehow the task seemed more manageable than usual. “Whatever happens tonight, happens,” I said encouragingly to myself. “No matter what, there will always be a tomorrow.”

My improved mood was no doubt related to my recent dip in the pool. Like all types of physical activity, swimming can improve your mood by stimulating the production of Endorphins – natural opioids that are produced in the brain – as well as other neurotransmitters such as dopamine and serotonin.

But the benefits of swimming go way beyond temporarily improving your mood – especially now.

Change your mind

As we all get out of isolation, experts say caring for our mental health must be a top priority.

“Americans have faced unprecedented hardships in the past few months, but by focusing daily on caring for our own emotional well-being and supporting the well-being of those we love, we can reduce the impact of the COVID-19 pandemic on successfully weakening mental health. “Former US surgeon general Dr. Jerome Adams said in one Press release earlier this year.

“While this is a difficult time in our nation’s history, I remain steadfast in encouraging Americans to use healthy mechanisms to deal with this,” he added.

Mindfulness Counts: 5 Ways To Start MindfulnessThe prevalence of depressive symptoms in the United States has more than tripled with the spread of Covid-19, so a recent study in JAMA magazine. Some high-risk groups, including healthcare workers and those under the age of 30, were even more at risk of developing anxiety or depression because of the pandemic, according to another study published in the journal Journal of Psychiatric Research. Regular exercise – including swimming, To run, yoga, Strength training and even Tai chi – remains one of the most powerful tools we have to improve our mood and overall mental health. A meta-analysis from 2016 that combined data from 23 randomly controlled studies showed that physical activity was comparable to both antidepressants and psychotherapy in the treatment of depression. Although part of this is due to the production of endorphins, exercise also leads to important structural changes in the brain, particularly in a primitive brain structure called Hippocampus. Along with another brain structure called the amygdala, the hippocampus is heavily involved in memory formation and the regulation of emotions. Regular aerobic exercise – such as running and swimming – over time reduces inflammation and promotes nerve growth in the hippocampus, with positive effects on both mood and memory, studies have shown. Vice versa, Atrophy or shrinkage of the hippocampus has been linked to the development of mood disorders such as depression and bipolar disorder. Subscribe to CNN’s Fitness But Better newsletter: Back into the groove. Sign up for our series of newsletters to find a healthy routine supported by experts

Defying evolution

Not only is our mental health affected by the Covid pandemic: our bodies have also taken its toll. According to another, the average American gained about 7 pounds during the pandemic Study in JAMA. released. “The long-term health effects of COVID are worrying,” said Daniel Liebermann, Professor in the Department of Human Evolutionary Biology at Harvard University, in an email. Lieberman is also the author of “Exercised: Why something we never wanted to do is healthy and rewarding. ” Use your breathing for less stress and more focused rest

“To what extent those extra pounds are from diet, (lack of) exercise, or stress is difficult to decipher, but well-documented decreases in physical activity are clearly a cause,” added Lieberman.

As with all aerobic exercise, swimming is also a great way to strengthen muscles and burn fat. However, swimming has an additional benefit: human swimmers typically use around seven times as much energy to cover a certain distance as running.

This is because humans didn’t necessarily develop into experienced swimmers, according to Lieberman. The fastest human swimmers can only reach speeds of about 7.2 miles per hour – the speed at which most people transition from a fast walk to a slow run.

While this aspect of swimming can be frustrating for new swimmers, it may not be bad at losing weight.

“You only have to watch a seal or beaver swim to see that even the best human swimmers do poorly compared to swimming-adapted mammals,” added Lieberman. “The good news is that this inefficiency makes swimming a very effective exercise for burning calories.”

19 things to do to get the whole family outside this summer (CNN Underscored)There are many other aspects of swimming that make it a uniquely beneficial form of exercise. For example, when we swim we are completely horizontal, what increases blood reflux from the venous system to the heart. This particular aspect of swimming also has additional benefits for the heart. For example, the maximum heart rate when swimming is about 10-15 beats slower than when running, which increases the time the heart can relax and fill with blood, known as the “diastolic function”. This becomes the heart Stroke volume – or the amount of blood the heart pumps with each beat – increases by 30 to 60% when swimming, according to a 2013 study International Journal of Cardiology. Swimming is also different from other aerobic exercise in that it is based on controlled breathing. This can increase in over time Total lung capacity and improved general lung function.

But if you have limited access to a pool or large body of water, or if you feel like you can’t swim for long, don’t worry: the most important thing is that you stay active this summer and choose an activity that you enjoy do, so Lieberman.

“If you have trouble moving, remember that even a little exercise has tremendous benefits to your physical and mental health. You don’t have to run a marathon or swim in the English Channel,” Lieberman said. “And if you don’t enjoy exercising, find a way to make it comfortable. For most people, that means making it social. Training with friends will help you find the motivation to show up and move on. “

Dr. Mark Dear is an intern at the Johns Hopkins Bayview Medical Center in Baltimore and was a Stanford-CNN Global Health and Media Fellow from 2017-2018. He plans to focus his medical career on basic HIV and LGBTQ care.