A new study suggests exercising after receiving the COVID-19 or flu vaccine increases your antibody response. Researchers at Iowa State University found that 90 minutes of exercise caused a consistent increase in serum antibodies for four weeks after study participants received the Pfizer COVID-19 vaccine. The study subjects either cycled on a stationary bike or walked briskly for 90 minutes after getting their jab, says Study Finds.

“Our preliminary results are the first to demonstrate a specific amount of time can enhance the body’s antibody response to the Pfizer-BioNTech COVID-19 vaccine and two vaccines for influenza,” said lead study author kinesiologist Marian Kohut. The researchers looked to see if 45 minutes of exercise had the same effect, and it did not.

According to Medical Daily, the participants, many of whom were overweight or obese, were divided randomly into two groups. One was asked to follow an assigned exercise routine and the other was asked to continue routine activities after receiving the first vaccine dose.

The exercise participants were found to have “significantly greater” antibodies compared to the study subjects who did not exercise, said the researchers.

“These findings suggest that adults who exercise regularly may increase antibody response to influenza or COVID-19 vaccines by performing a single session of light-to-moderate-intensity exercise post-immunization,” the study authors stated.

Both groups reported the same degree of side effects, so exercise did not change that profile, according to Medical Daily. The new study’s findings are in line with previous results that showed that exercise enhanced antibody response even preceding immunization. Researchers speculate that exercise acts as a stressor on the body that increases antibody reaction.

They also believe that exercise helps circulate blood and lymph flow throughout the body, which means greater immune cell circulation, says Study Finds. When the immune cells make their way around the body, they are more likely to detect a threat.

“But a lot more research is needed to answer the why and the how,” said Kohut. “There are so many changes that take place when we exercise — metabolic, biochemical, neuroendocrine, circulatory. So, there’s probably a combination of factors that contribute to the antibody response we found in our study.”