Taking a long, brisk walk, jog, or bike
ride after your next
COVID-19 or
flu vaccine might amplify the benefits of the
shot, according to a new study of exercise and immunization. The study, which
involved 70 people and about 80 mice, looked at antibody responses after a jab
with the influenza vaccine or both rounds of the
Pfizer-BioNTech COVID-19
vaccine. It found that people who exercised for 90 minutes right after their
shot subsequently produced more antibodies than people who did not. The extra immunity boost, which should help reduce their risk of falling seriously ill from
those diseases, did not seem to trigger an increase in side effects.
اضافة اعلان
The study’s 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 may prime our bodies to respond with extra
robustness to flu and COVID-19 vaccines.
Exercise alters
‘almost all’ our immune cells.
The relationship between
exercise and immunity is, in general, well established. Most studies show that
being physically active helps protect us against catching colds and other mild,
upper-respiratory-tract infections. Being fit may also ease the severity of
infection if we do get sick. In a study last year of almost 50,000
Californians
who developed COVID-19, for example, those who had been exercising regularly
before their diagnosis were about half as likely to wind up hospitalized as
people who rarely worked out.
On the other hand, extreme exercise might undermine
our immunity. Marathon runners often report getting sick after races, and lab
mice that run to utter exhaustion tend to become more susceptible to the flu
than sedentary animals.
Overall, though, exercise appears to offer a potent
boost to our immune systems. “The behavior of almost all immune cell
populations in the bloodstream is altered in some way during and after
exercise,” a recent review of past research on the topic concluded.
Is there a right
‘dose’ of exercise?
But few of these earlier
studies aimed to determine the best timing and amounts of exercise to amplify
vaccine effects, and none looked at COVID-19 shots, which have only been
available since late 2020. So, for the new study, published recently in Brain,
Behavior, and Immunity, a group of immunobiologists and exercise scientists at
Iowa State University in Ames asked people getting a flu or COVID-19 shot to
also work out.
The behavior of almost all immune cell populations in the bloodstream is altered
in some way during and after exercise.
They began by inviting dozens of healthy adults ages
18–87 who said they exercised occasionally to come to the lab for a flu shot.
The scientists also coordinated with local COVID-19 vaccination sites to
recruit 28 men and women who were getting their first
COVID-19 shots. Before
the vaccinations, they drew blood from all the volunteers to check antibody
levels.
Then they randomly assigned everyone either to sit
quietly or to exercise for 90 minutes after getting their shot. Earlier
research had suggested that exercising after getting a
vaccine increased the
immune response more than the same level of activity beforehand. And they
settled on 90 minutes as a general exercise target because unpublished research
from their lab suggested that amount of exercise substantially increased the
production of a substance in the blood called interferon alfa that can spark
the creation of immune cells.
The exercising volunteers then rode a stationary
bike or walked rapidly for 90 minutes after their vaccinations, either at the
lab or outside on the sidewalks near the COVID-19 vaccine sites. They worked
out at a mildly challenging pace, aiming to keep their heart rates between
about 120 and 140 beats per minute. But the researchers also asked some of the
flu-shot volunteers to ride for only 45 minutes, to see if the shorter workout
might be equally effective at amping immunity.
Because antibody levels tend to build in the weeks
following a vaccination, the researchers drew blood from everyone again two and
four weeks after their shots.
45 minutes is not
enough
After a month, everyone’s
antibody levels to the flu or COVID-19 shot rose substantially, as expected
after getting a vaccine. But they were highest in the men and women who had
exercised for 90 minutes afterward. This antibody bonus was not huge. “But it
was statistically significant,” said Marian Kohut, a professor of kinesiology
and member of the
Nanovaccine Institute at Iowa State, who oversaw the new
study.
People who exercised also did not report additional
side effects after their shots. (They did not experience fewer side effects,
either.)
Interestingly, 45 minutes of exercise in this study
was not enough to bump up antibodies. The shorter workout probably did not
increase the levels of substances needed to amplify immunity, including
interferon alfa, Kohut said.
The researchers also repeated the flu vaccine
experiment in mice that either jogged afterward or stayed still. The
researchers checked their blood for interferon alfa levels and found them
higher with exercise. But if the scientists chemically blocked production of
the substance, the animals gained a little extra antibody benefit from
exercise, suggesting exercise improves vaccine response in part by first
raising interferon alfa levels.
The upshot of the results, then, is that “if you have the
time and a safe place to exercise after your vaccination,” a moderate 90-minute
exercise session may make your vaccine response greater, Kohut said, without
adding to side effects.
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