Editor’s note: Dr. Mark Lieber is a resident physician in internal medicine at the Johns Hopkins Bayview Medical Center in Baltimore and was the 2017-2018 Stanford-CNN Global Health and Media Fellow. He plans to focus his medical career on HIV and LGBTQ primary care.
(CNN) — I recently went swimming for the first time in over a year. Standing in the sparkling blue swimming pool at my local gym, I tried to remember many of the stressful events of the past 16 months: moving to a new city (Baltimore) during a pandemic, starting a new residency training program. in internal medicine and the care of patients with and without covid-19 in the hospital had taken their toll on me.
The first thing I thought when diving into the surface of the water was that I felt more buoyancy than usual, probably due to the extra kilos that the quarantine had brought me. But as I continued to slide through the water, my initial worry about gaining weight was replaced by a feeling of catharsis, as if the water was cleaning me from the stress accumulated during the coronavirus pandemic.
Stroke after stroke, I could feel my mood lift, my mind clear, and my body loosen.
Thirty minutes later, I emerged from the pool feeling confident and clear-headed, ready to begin the first of four night shifts in the intensive care unit. I tend to feel a little fearful of the first night shift, but somehow the task seemed more manageable than usual. “Whatever happens tonight, it will happen,” I said to myself, to cheer myself up. “Whatever happens, there will always be tomorrow.”
The improvement in my mood was undoubtedly related to my recent stint in the pool. Like all types of physical activity, swimming can improve mood by stimulating the production of endorphins (natural opioids produced in the brain), as well as other neurotransmitters such as dopamine and serotonin.
But the benefits of swimming go far beyond a momentary improvement in mood, especially now.
Change your mind
As we all come out of isolation, experts say that addressing our mental health should be a top priority.
“Americans have faced unprecedented difficulties in recent months, but by daily focusing on taking care of our own emotional well-being and supporting the well-being of our loved ones, we can successfully mitigate the effects of the COVID-19 pandemic. on mental health, “said former US chief health officer Dr. Jerome Adams in a press release earlier this year.
“Although this is a difficult time in our nation’s history, I remain firm in encouraging Americans to use healthy coping mechanisms,” he added.
The prevalence of depressive symptoms in the United States more than tripled as COVID-19 spread, according to a recent study published in the journal JAMA. Some high-risk groups, such as healthcare workers and those under 30, were at even higher risk of developing anxiety or depression due to the pandemic, according to another study published in the Journal of Psychiatric Research.
Regular exercise – including swimming, running, yoga, weight training, and even tai chi – remains one of the most powerful tools we have for improving our mood and overall mental health. A 2016 meta-analysis that combined data from 23 randomized controlled trials showed that exercise was comparable to both antidepressants and psychotherapy in treating depression.
While part of this is due to the production of endorphins, exercise also produces important structural changes in the brain, particularly in a primitive brain structure called the hippocampus. Along with another brain structure called the amygdala, the hippocampus is heavily involved in memory formation and the regulation of emotions.
Over time, regular aerobic exercise, such as running or swimming, reduces inflammation and encourages nerve growth in the hippocampus, with positive effects on both mood and memory, studies have shown. In contrast, atrophy, or shrinkage, of the hippocampus has been linked to the development of mood disorders such as depression and bipolar disorder.
Our mental health is not the only thing that has been affected by the covid-19 pandemic: our bodies have also suffered the impact. According to another study published in JAMA, the average American gained about 3 kilos during the pandemic.
“The long-term health effects of COVID-19 are concerning,” Daniel Lieberman, a professor in the department of human evolutionary biology at Harvard University, said in an email. Lieberman is also the author of “Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding.”
“It is difficult to unravel to what extent these added kilos come from diet, (lack of) exercise or stress, but the well-documented decline in physical activity is clearly one of the causes,” Lieberman added.
Like all forms of aerobic exercise, swimming is also a good way to build muscle and burn fat. But swimming has an additional advantage: swimmers typically use seven times more energy to cover a given distance than to run.
This is because humans did not necessarily evolve to be expert swimmers, according to Lieberman. The fastest human swimmers can only reach speeds of about 6.5 kilometers per hour, the speed at which most people go from a brisk walk to a slow run.
Although this aspect of swimming can be frustrating for new swimmers, when it comes to losing weight, it may not be a bad thing.
“You only have to watch a seal or beaver swim to realize that, compared to mammals adapted to swimming, even the best human swimmers perform poorly,” adds Lieberman. “The good news is that this ineffectiveness makes swimming a very effective exercise for burning calories.”
There are many other aspects of swimming that make it an especially beneficial form of exercise. For example, when we swim, we are completely horizontal, which increases blood return from the venous system to the heart.
This distinctive aspect of swimming also carries additional cardiac benefits. For example, maximum heart rates are about 10-15 beats slower during swimming compared to running, increasing the time the heart can relax and fill with blood, known as “diastolic function.” As a result, the stroke volume of the heart, that is, the amount of blood pumped by the heart during each beat, increases between 30% and 60% during swimming, according to a 2013 study published in the International Journal of Cardiology.
Swimming is also different from other forms of aerobic exercise because it relies on controlled breathing. Over time, this can lead to an increase in total lung capacity and an improvement in the overall function of the lungs.
But if you have limited access to a pool or body of water, or feel like you can’t swim for a long time, don’t worry: The most important thing is that you stay active this summer and choose an activity that you enjoy doing, according to Lieberman.
“If you struggle to exercise, remember that even a little exercise has huge benefits for your physical and mental health. You don’t have to run a marathon or swim the English Channel,” says Lieberman. “And if you don’t like exercising, find a way to make it enjoyable. For most people, that means being social. Exercising with friends will help you find the motivation to get started and keep going.”