Marian Kohut, a professor in kinesiology, has discovered that exercising after a flu vaccination improves the immune response of obese adults. Photo by Wyeth Lynch.
Marian Kohut, a professor in kinesiology, has discovered that exercising after a flu vaccination improves the immune response of obese adults. Photo by Wyeth Lynch.

ISU researchers discover exercise boosts immunity in obese adults

As flu season approaches, Marian Kohut, a professor in kinesiology at Iowa State University, is working to understand the connection between physical activity and immune response to flu vaccines.

By reanalyzing data from a previous study on older adults, Kohut and her research team have discovered that one year of moderate, post-vaccination exercise can improve the immunity of obese subjects – a group that typically produces a less vigorous response to the vaccine.

"We divided the obese subjects into two groups – one doing cardiovascular exercise like biking and aerobics, and one working on flexibility, stretching, and strength training,"  Kohut said. "As long as they improved overall fitness – whether through cardio or strength training – they had a slightly better immune response." 

Using an animal model, Kohut's team also found that several months of moderate exercise training prior to influenza infection reduced the amount of virus in the lungs of obese and non-obese mice.

While Kohut recommends ongoing cardiovascular training as the ideal approach to flu prevention, even a short burst of post-vaccination physical activity could help. Last fall, her research team observed that a 90-minute session of exercise following vaccination increased antibody production in young adults. Following that study, Justus Hallam – a graduate student in kinesiology – ran similar trials in mice and achieved similar results.

"Now that we know exercise is effective, we're interested in finding out how it works,"  Kohut said. "Is it a question of circulation? Does exercise get the vaccine to the lymph nodes more quickly?" 

To answer those questions, Kohut's team will inject fluorescent particles in mice before a 90-minute exercise session. Tracing the particles' pathways through the body during physical activity will help her team better understand the mechanisms involved in enhancing immune response.

In a previous study examining the effects of 90-minute post-vaccination exercise sessions, Kohut's team also observed that the immune system produced more interferon – a chemical that interferes with viral replication.

"We're doing trials looking at whether interferon has any role in altering the vaccine response,"  Kohut said.

Although Kohut recommends exercise as a way to stay healthy and flu-free this season, she also cautions against going overboard.

"Keeping the exercise moderate is key,"  Kohut said. "There's evidence that intense, prolonged exercise – running a marathon, for example – actually increases your susceptibility to respiratory infection, so avoid overtraining." 

Contacts:

Marian Kohut
515-294-8364
mkohut@iastate.edu

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