Exercising before or after a flu vaccination may make it work better

People who are usually physically active had increased antibody levels if they exercised around the time they received their flu shot

By Grace Wade

For people who are usually physically active, working out around the time of their flu shot may increase the vaccine’s efficacy. The benefit is even more pronounced if they train the muscles about to get jabbed.

Erika Bohn-Goldbaum at the University of Sydney in Australia and her colleagues collected data from seven trials to see how exercise impacts the immune response to flu vaccination. Of the 550 healthy adult participants, 382 exercised for 15 to 50 minutes either before or after they received their flu shot. The other 168 sat inactive for an equal amount of time. Researchers collected their blood samples four to six weeks after inoculation to measure antibody levels.

About 61 per cent of the participants were already active, meaning they engaged in 2.5 hours of moderate physical activity per week. This group had a better immune response to the vaccine compared with people who were inactive, a finding in line with previous studies. And they got an additional boost if they exercised around the time of vaccination: more than a month later, their antibody levels were significantly higher than those of people who sat idly. This was only true if their flu shot targeted the H1 influenza strain, not the H3 or B strains. Exercise had no significant impact on the antibody levels of people who were usually inactive.

“If you are a physically active, not-obese person, we know from many studies that your antibody response to influenza and other vaccines is better,” says David Nieman at Appalachian State University in North Carolina.

Exercise spurs immune cells to circulate in the bloodstream, where they can better react to pathogens, or in this case, vaccines, says Nieman. However, this effect only lasts for a few hours, which is why consistent physical activity is key for a robust immune response.

Physically active participants who engaged in upper body resistance training before vaccination had slightly higher antibody levels than those who did other exercises. This suggests that training the muscles near the injection site also improves immune response, says Bohn-Goldbaum.

“We think muscle damage from exercise actually activates local danger signals which stimulate [certain immune] cells and gets the adaptive immune response going,” says Bohn-Goldbaum.

Journal reference: PLoS One, DOI: 10.1371/journal.prone.0268625

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