Research: Doing This One Thing for 90 Minutes After Your Flu or COVID Vaccine Maximizes Your Immunity

While it might be tempting to take it easy and skip the gym after getting a vaccine or two, science says it might be to your benefit to squeeze in a workout. According to a 2024 review of research published in Sports Medicine and Health Science, not only is it OK to exercise after your seasonal vaccinations, but a little activity might give your immune system a competitive edge. 

Exercise for better immunity

The research points to a 2022 study published in Brain, Behavior, and Immunity that presents a compelling argument to get moving after a shot. 

In this study, participants who did 90 minutes of mild-to-moderate intensity exercise—such as cycling on a stationary bike or taking a brisk walk—right after their flu or COVID vaccine produced a notably stronger antibody response over the following four weeks. 

Here’s why this is significant: Antibodies are your defense mechanism against harmful invaders like viruses and bacteria. They are pivotal in the immune response, and vaccines train your immune system to produce them.

By comparison, participants who rested or went about their day as usual didn’t experience this additional immune boost. The researchers found similar results when they repeated the experiment with mice. 

How you exercise matters, too

While the 2022 study focused on exercising after vaccination, the 2024 review found that working out before getting your shot can enhance vaccine effectiveness, too. 

It also highlights that there’s a sweet spot for how you exercise to reap the best benefits:

• Type: Light-to-moderate aerobic exercise. Resistance, flexibility, or balance training did not yield the same immunity benefit.
• Duration: 90 minutes is key—shorter, 45-minute sessions did not significantly impact antibody levels. 
• Heart rate: Aim for 60% to 70% of your max heart rate—this will differ from person to person, but the 2022 study uses a heart rate zone of 120 to 140 beats per minute. 

Notably, the study included a diverse range of participants, with nearly half being overweight or obese. This suggests the immune boost from exercising the day you get vaccinated applies across a variety of fitness levels. 

The science of exercise and immunity

Research further explains how exercise triggers numerous physiological changes, from metabolic and circulatory shifts to enhanced immune activity. Working out boosts both blood and lymph flow, which encourages immune cells to circulate more efficiently, which in turn helps them become better at detecting and attacking foreign invaders. 

In the 2022 study, researchers identified another possible mechanism at work. Using a mouse model, they found that interferon alpha—a protein your body produces during exercise—plays a role in creating virus-specific antibodies and T-cells. 

Stay active to stay protected

While a 90-minute stroll appears to amplify your vaccine response, the 2024 research emphasizes that consistent, moderate aerobic activity keeps your immune system primed throughout cold and flu season. It found that:

• Regular light-to-moderate exercise strengthens your baseline immune defenses. 
• Active people tend to get fewer respiratory infections.
• Overtraining without enough rest can temporarily suppress immunity—so balance is essential. 

With the arrival of flu season, pairing your vaccination with an exercise session could give your body a protective boost. Just remember: moderation and consistency are key. A simple daily movement habit, such as a walk or a gentle bike ride, may help you stay healthier all season long. 

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