Research by University of Bath could finally overturn the persistent myth that strenuous exercise suppresses the body's immune system and makes people "more susceptible to infections".

Published in the journal Frontiers in Immunology, the research reinterprets scientific findings from the last few decades and argues that exercise – instead of hampering immunity – could be beneficial for immune health.

Research on marathon runners in the 1980s suggested that many competitors had symptoms of infections in the period after races. This lead to an understanding that strenuous exercise increases infection risk by suppressing the immune system.

The University of Bath report entitled Debunking the Myth of Exercise-Induced Immune Suppression: Redefining the Impact of Exercise on Immunological Health Across the Lifespan, however, turns the tables on those long-held beliefs.

The study looked at the way in which immune cells react to exercise.

During exercise, the number of immune cells in the bloodstream can increase by up to 10 times. In the hours following exercise, the number of peripheral blood lymphocyte – and the functional capacity of the lymphocyte pool – is then decreased below pre-exercise levels. This has led to some to propose that exercise induces a short-term window of immune suppression.

The study suggests that, rather than been "lost", the cells move to other parts of the body which are more likely to become infected – such as the lungs.

"The acute and transient lymphopenia, one to two hours after exercise, is beneficial to immune surveillance and regulation," the report states.

"In what appears to be a highly specialised and systematic response, exercise redeploys immune cells to peripheral tissues – such as mucosal surfaces – to conduct immune surveillance.

"This means that there is strong evidence that a reduction in the frequency and function of lymphocytes (and other immune cells) in peripheral blood in the hours following vigorous and prolonged exercise does not reflect immune suppression.

"Instead, the observed lymphopenia represents a heightened state of immune surveillance and immune regulation driven by a preferential mobilisation of cells to peripheral tissues.

"As such, nutritional interventions, which have been employed to dampen the magnitude of exercise lymphopenia are unlikely to reduce the incidence of infections, but interventions that augment exercise-induced lymphocyte trafficking may provide benefits."

To read the full report, click here for the Frontiers in Immunology website