Caution is key when resuming exercise after COVID-19

Q: I'm a 38-year-old man, very athletic, and I got really sick with the coronavirus. I didn't land in the hospital, but it's been a month and I'm still not 100%. I want to get back to running and lifting weights. Is it safe to exercise after COVID-19?

A: We have to begin with the reminder that we're still in the early stages of learning about the virus and the disease that it causes. That said, a growing body of research suggests that, for some people who have recovered from COVID-19, a range of adverse health effects can continue after the initial disease has run its course. This is particularly true for older patients and those with preexisting health conditions. There may also be a link between how severe someone's illness was and their risk of developing more serious complications once they have recovered.

Although we think of COVID-19 as a respiratory illness, it can damage other organs, adversely affect the body's blood-clotting mechanisms and cause lingering systemic inflammation. Scans of patients who have recovered from COVID-19 reveal damage to the lungs, heart and kidneys, as well as dangerous levels of blood-clot production. Survivors report lingering pain, shortness of breath, so-called “brain fog” and persistent fatigue. Some people experience heart arrhythmias, and some develop hypertension. A number of recovering patients also find themselves dealing with ongoing episodes of depression and anxiety.

When it comes to exercise, the current advice for people recovering from mild or moderate COVID-19, and who were not hospitalized, is to wait at least two weeks before resuming physical activity. It's not only much-needed rest; it's also an opportunity to evaluate how you feel being up and about, what kind of activity causes fatigue and at what point you tire. For those who experience a continual recovery in the weeks after being ill, it is considered safe to gradually resume physical activity once the two-week rest period is over. But it's important to ease back into being active. Pushing yourself post-illness does more harm than good.

Because you report you were significantly ill with COVID-19, you should check in with your health care provider before working out again. Describe the course of your illness and everything you're experiencing since recovering. It's possible you'll be asked to undergo some diagnostic tests to assess heart and lung function before being cleared for more vigorous activity. Athletes who have recovered from COVID-19 are finding initial workouts to be challenging. In addition to a light cough and mild shortness of breath, they report a dive in stamina. If you experience more severe symptoms, such as an irregular or racing heartbeat, chest pain or tightness, or severe or long-lasting shortness of breath, it's important to immediately stop what you're doing and check in with your health care provider.

Athletes are used to bouncing back from a cold or the flu, and the slow trajectory of COVID-19 recovery can be frustrating. But please don't try to push it. Moving forward slowly and cautiously is your best shot at a full recovery.

Q: I've heard that a lot of people don't get enough vitamin D in their diet. What about getting it from the sun? Is that too risky? Also, what happens if you don't get enough?

A: Vitamin D is a fat-soluble nutrient that our bodies require in order to absorb calcium from the intestines. That calcium is then used to harden the tissues of the skeleton, a process known as mineralization. Vitamin D is also crucial to bone growth, plays a role in managing inflammation, helps prevent involuntary muscle spasms and aids in the regulation of blood phosphorus levels.

Not getting enough vitamin D makes it difficult to maintain adequate levels of calcium and phosphorus, which can cause bones to gradually become thin and brittle. Together with calcium, vitamin D also helps protect older adults from osteoporosis. In children, a lack of the vitamin can lead to rickets, a disease that interferes with mineralization. Rickets is a sometimes painful disease, marked by poor skeletal formation and soft, weak bones that can become malformed.

When our skin is exposed to sunlight, our bodies become natural vitamin D factories. The energy in ultraviolet rays triggers a complex chemical reaction that, along with help from the liver, kidneys and certain cellular structures, results in the formation of vitamin D. The nutrient is also naturally available in fatty fish, including tuna, mackerel, salmon and sardines, and in smaller amounts in certain foods such as beef liver, cheeses, egg yolks and some mushrooms. However, we don't eat these foods in large enough quantities to satisfy our body's ongoing need for vitamin D. To help make up for a potential deficit, a range of prepared foods are fortified with the nutrient. These include orange juice, breakfast cereals and dairy products, as well as some soy, rice and noodle products.

The amount of vitamin D that you need to maintain optimal bone health depends on your age. Infants up to 1 year old should get 400 international units (IU) per day. Children, teens and all adults up to the age of 70 are advised to get 600 IU. After age 70, when our bodies become less efficient, the recommendation increases to 800 IU per day.

It's rare, but possible, to get too much vitamin D. The addition of the nutrient to prepared foods is carefully regulated, and our bodies naturally limit the amount they manufacture from sun exposure, so you're not going to run into problems there. If you're going to rely on vitamins or supplements for your vitamin D intake, be sure to check with your health care provider.

Getting enough vitamin D from the sun depends on location, weather and skin type. Also, sunscreen limits how much a person can produce. For those with light skin, 15 to 30 minutes of full sunlight on bare arms, legs or torso a total of two to three times per week is adequate. Due to the protective effects of melanin, darker skin requires longer exposure. People with any kind of skin cancer history or risk should rely on diet and supplements to get their daily allowance.

• Dr. Eve Glazier is an internist and associate professor of medicine at UCLA Health. Dr. Elizabeth Ko is an internist and assistant professor of medicine at UCLA Health. Send your questions to askthedoctors@mednet.ucla.edu.