A new study shows some interesting evidence in regards to antibodies and what’s safe to do right after getting a vaccine.

Vaccines prompt an immune reaction from your body, creating antibodies and protecting you from a virus. It’s understood that the stronger your reaction, the better and more thorough your protection will be, with your body producing the necessary antibodies to fight off the virus when exposed to it in the future. A new study found that exercising after getting your COVID-19 shot might help you produce even more antibodies. Published in the Journal of Brain, Behavior and Immunity, the study found that active adults who worked out for over 90 minutes after getting their vaccine demonstrated increased serum antibodies.

Researchers from Iowa State University studied participants who received a flu shot and a COVID-19 shot. For the COVID group, researchers collected blood samples prior to their shots, two weeks after receiving their first shot, and one week after receiving their second shot. The flu group submitted a blood sample before their immunization, and on weeks two and four after their injection.

The flu group was asked to exercise for 45 minutes, 90 minutes, or not at all, while the COVID-19 group was asked to exercise for 90 minutes or not at all, all completing their workouts soon after their immunization. Researchers discovered that those who worked out consistently for 90 minutes showed increased serum antibodies for up to 4 weeks after their shot.

“Based on the data we have, it appears that as long as individuals are in the 60 to 70 percent of the age-based estimate of max heart rate, we see the same benefit [of increased antibodies],” said lead researcher Marian Kohut, Ph.D.

Some of the study’s most interesting findings were the ones that demonstrated how important the duration of the workouts was in terms of increasing antibodies. People who worked out for 45 minutes or with vigorous intensity did not show any benefits; what mattered was the fact that people completed their 90 minutes at the pace of their choosing.

While small, the study shows some interesting evidence in regards to antibodies and what’s safe to do right after getting a vaccine. Still, it’s important for people to avoid working out if they have a fever or some other side effect from their immunization that makes them feel weak and like they can’t take on a long workout.