Exercise may increase the effectiveness of your Covid-19 vaccine, a new study found: Here's how to get the most benefit

Having the most protection from severe outcomes following Covid-19 infection is largely attributed to vaccination. But, the shot's effectiveness may be enhanced by physical activity, a new study found.

Elevated levels of physical activity appeared to be associated with higher effectiveness from the primary series of the Covid-19 vaccination, according to new research published in the British Journal of Sports Medicine. 

"The higher the dose of exercise, the greater the protective effect, obviously to an extent," Jon Patricios, professor of sport and exercise medicine at Wits University in Johannesburg and co-author of the study, tells CNBC Make It. 

So, how often and at what intensity should you be exercising to get the most benefit from your Covid-19 vaccinations? Here's what Patricios and his co-authors discovered.

2.5 hours of exercise a week may increase protection against severe outcomes from Covid in vaccinated people

Researchers found that vaccinated people with the most protection from severe outcomes, like hospitalization, after Covid-19 infection, followed these exercise guidelines:

• Frequency: They completed at least 150 minutes, or two and a half hours, of physical activity each week.
• Intensity: Their physical activity was moderate intensity, which means their heart rate was between 70% or 79% of their maximum heart rate while exercising.

Participants within this group were 2.8 times less likely to develop severe outcomes from Covid-19 than people who rarely exercise. Or, in simpler terms, their vaccines were 25% more effective at protecting them from these outcomes than sedentary people.

In a video embedded in the study, visual representations of weight-lifting and running are highlighted as some of the exercises that the group engaged in.

"It's likely that at a higher level of physical activity, you're getting more positive stimulation of that immune response," says Dr. Elizabeth Joy, senior medical director for wellness and nutrition at Intermountain Healthcare, who wasn't involved in the study.

"In turn, that results in the observed decrease in disease burden."

Yet, even vaccinated people who exercised between 60 minutes and 149 minutes were 1.4 times less likely to have severe cases of Covid infection.

Here's how the study was conducted

Researchers analyzed data collected from the biggest health insurer in South Africa of nearly 200,000 vaccinated adults in the country, including both men and women. At the time that the study was conducted, only the Johnson & Johnson vaccine was available.

The data included Covid-19 PCR test results from February to October of 2021. And the number of minutes of physical activity, step count and heart rate data were tracked for each person using a wearable device.

Exercise may lower chances of severe outcomes from Covid in unvaccinated people, too

"We had another study which showed that in people who contracted Covid – and those were unvaccinated individuals – those who engaged in the recommended 150 minutes a week of exercise, had better outcomes," says Patricios.

"They were admitted to hospitals less, fewer of them were in the ICU and on respirators and fewer of them died."

Similar to his research, a study was conducted on over 48,000 participants with Covid, before vaccines were available, to determine if exercise was associated with a lower risk of severe outcomes from the disease. 

Researchers found that those who walked or worked out consistently, prior to infection, were about half as likely to be hospitalized due to Covid.

"This just further adds to that evidence base that people who are more physically active are healthier," says Joy. 

While it has been widely studied that exercise can lower risks of noncommunicable diseases like dementia and cancer, "physical activity is also a successful strategy to prevent communicable diseases like Covid-19," Joy notes.

When it comes to physical activity for better health outcomes, she says, "none is bad, some is good [and] more is better."

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