Going for a long, brisk walk, jog or bike ride after your next Covid or flu shot could amplify the benefits of the vaccine, according to a researcher. new exercise and immunization study. The study, involving 70 people and about 80 mice, looked at antibody responses after an injection with either the Pfizer-BioNTech flu vaccine or both rounds. COVID-19 vaccine. He found that people who exercised for 90 minutes right after the injection produced more antibodies than people who didn’t. The extra immune boost, which should help reduce the risk of getting seriously ill from these diseases, did not seem to trigger an increase in side effects.
The study results are preliminary and need to be tested in larger numbers of people. But the findings add to mounting evidence that being fit and physically active can prime our bodies to respond more robustly to flu and Covid vaccines.
Exercise alters ‘nearly all’ of our immune cells
The relationship between exercise and immunity is generally well established. Most studies show that being physically active helps protect us against colds and other minor infections of the upper respiratory tract. Being fit can also ease the severity of an infection if we do get sick. in a study last year of nearly 50,000 Californians who developed Covid, for example, those who had been exercising regularly before their diagnosis were about half as likely to end up hospitalized as people who rarely exercised.
On the other hand, extreme exercise could undermine our immunity. Marathon runners often report get sick after races, and lab mice that run to total exhaustion tend to become more susceptible to the flu than sedentary animals.
In general, though, exercise seems to offer a powerful boost to our immune systems. “The behavior of almost all populations of immune cells in the bloodstream is altered in some way during and after exercise,” a recent review of previous research on the subject concluded.
Therefore, it should come as no surprise that exercise can also affect vaccine response. In some past studies, performing arm exercises before a flu shot increased levels of antibodies and specialized immune cells more than sitting quietly. Y in a 2020 studyelite competitive athletes in the middle of their training seasons generated more antibodies and immune cells after getting vaccinated against the flu than a control group of healthy youngsters.
Is there a correct ‘dose’ of exercise?
But few of these earlier studies aimed to discover the best time and amount of exercise to amplify the effects of the vaccine, and none looked at covid vaccines, which have only been available since late 2020. So for the In a new study, published this week in Brain, Behavior, and Immunity, a group of immunobiologists and exercise scientists at Iowa State University in Ames, Iowa, asked people getting flu or covid vaccines to also exercise. .
They began by inviting dozens of healthy adults ages 18 to 87 who said they exercised occasionally to come to the lab for a flu shot. The scientists also coordinated with local COVID vaccination sites to recruit 28 men and women who were receiving their first COVID vaccinations. Before the vaccinations, they drew blood from all the volunteers to check antibody levels.
They then randomly assigned everyone to either sit quietly or exercise for 90 minutes after receiving the injection. Previous research had suggested that exercising after receiving a vaccine increased the immune response more than the same level of activity before. And they settled on 90 minutes as their overall exercise goal because unpublished research from their lab suggested that the amount of exercise substantially increased the production of a substance in the blood called interferon alpha that can trigger the creation of immune cells.
The volunteers who exercised then rode a stationary bike or walked briskly for 90 minutes after their shots, either in the lab or outside on sidewalks near Covid vaccine sites. They exercised at a mildly challenging pace, aiming to keep their heart rates between 120 and 140 beats per minute. But the researchers also asked some of the flu-vaccinated volunteers to cycle for just 45 minutes, to see if the shorter workout might be just as effective at boosting immunity.
Because antibody levels tend to build up in the weeks after vaccination, the researchers bled everyone again two and four weeks after the injections. (People who received the Covid vaccine received their second injection in the meantime, as a second Pfizer injection is due three weeks after the first.)
45 minutes is not enough
After a month, everyone’s antibody levels against the flu or Covid vaccine increased substantially, as expected after receiving a vaccine. But they were higher in men and women who had exercised for 90 minutes afterwards. This antibody bonus was not huge. “But it was statistically significant,” said Marian Kohut, a professor of kinesiology and a member of the Iowa State Nanovaccine Institute, who oversaw the new study.
The exercisers also reported no additional side effects after their injections. (They also didn’t experience fewer side effects.)
Interestingly, 45 minutes of exercise in this study was not enough to increase antibodies. The shorter workout probably didn’t increase levels of substances needed to amplify immunity, including interferon alpha, Dr. Kohut said.
The researchers also repeated the flu shot experiment in mice that either jogged afterward or stood still. The researchers checked their blood levels of interferon alpha and found them higher with exercise. But if the scientists chemically blocked production of the substance, the animals derived a small additional antibody benefit from exercise, suggesting that exercise enhances the response to the vaccine in part by first raising interferon-alpha levels.
The bottom line of the results, then, is that “if you have time and a safe place to exercise after vaccination,” a 90-minute session of moderate exercise may boost your response to the vaccine, said Dr. Kohut, without adding effects
Will 60 minutes be enough?
However, the study was small and did not measure antibody levels for more than a month after vaccination. It also didn’t track whether people ultimately became infected with the flu or Covid, nor did it look at the levels of several other cells that can affect the immune response, Dr. Kohut noted.
An hour and a half is also a lot of exercise. “It’s important to remember that it took quite a sustained effort, 90 minutes at an increased heart rate,” said Carmine Pariante, a professor at King’s College London and editor of the journal in which the study appeared. “The combination of three different vaccines in humans and in an animal model is a unique strength of this study,” said Dr. Pariante, adding that it was reassuring that the increased antibody responses were present regardless of condition levels. physical condition of the vaccine recipient.
The researchers hope to study whether 60 minutes or other durations or intensities of exercise might be helpful, or the other way around, after vaccinations, and how long antibody responses might persist. They are already enrolling people for a longer-term study of the effects of exercise on Covid booster shots.
But for now, if you schedule a flu or covid shot, you can set aside an extra 90 minutes to quickly explore the nearby neighborhood on foot or by bike. It can simply provide an additional immune boost from your vaccine.