Vigorous Exercise Could Make a Person More Vulnerable to Respiratory Infection

Scientists from the Department of Energy’s Pacific Northwest National Laboratory (PNNL) analyzed more than 4,700 molecules — proteins, lipids, and metabolites — from 11 young firefighters who went through a rigorous training exercise, looking to understand what happens when the body undergoes intense physical exercise.

For this study, the intent was to increase safety for first responders and others.

“We wanted to take an in-depth look at what’s happening in the body and see if we’re able to detect danger from exhaustion in its earliest stages. Perhaps we can reduce the risk of strenuous exercise for first responders, athletes, and members of the military.”said Kristin Burnum-Johnson, a corresponding author of the study.

As expected, the team detected hundreds of molecular changes in the firefighters.

But in the saliva, the team found some unexpected results. There was a change in the microbial mix of the mouth — the oral microbiome — showing that the body was increasingly on the lookout for bacterial invaders.

Scientists also saw a decrease in signaling molecules important for inflammation and for fighting off viral infections.

A decrease in inflammation makes sense for people exercising vigorously; less inflammation allows people to breathe in air more quickly, meeting the body’s eager demand for more oxygen.

Having fewer inflammatory signals in the respiratory system helps the body improve respiration and blood flow.

But less inflammation leaves the body more vulnerable to viral respiratory infection — which is exactly what other scientists have noted in elite athletes and others who exercise vigorously.

Some studies have shown that a person is up to twice as likely to come down with a viral respiratory infection in the days after an especially energetic workout.

“People who are very fit might be more prone to viral respiratory infection immediately after vigorous exercise. Having less inflammatory activity to fight off an infection could be one cause,” said Ernesto Nakayasu, a corresponding author of the paper.

He notes that the work provides a molecular basis for what clinicians have noticed in their patients who do strenuous workouts.

The team hopes that the findings will help explain why some people are more vulnerable to respiratory infection after a workout.


Ernesto S. Nakayasu, Marina A. Gritsenko, Young-Mo Kim, Jennifer E. Kyle, Kelly G. Stratton, Carrie D. Nicora, Nathalie Munoz, Kathleen M. Navarro, Daniel Claborne, Yuqian Gao, Karl K. Weitz, Vanessa L. Paurus, Kent J. Bloodsworth, Kelsey A. Allen, Lisa M. Bramer, Fernando Montes, Kathleen A. Clark, Grant Tietje, Justin Teeguarden, Kristin E. Burnum-Johnson. Elucidating regulatory processes of intense physical activity by multi-omics analysis. Military Medical Research, 2023; 10 (1) DOI: 10.1186/s40779-023-00477-5

DOE/Pacific Northwest National Laboratory. “Vigorous exercise, rigorous science: What scientists learned from firefighters in training.” ScienceDaily. ScienceDaily, 9 November 2023. <>.

Materials provided by DOE/Pacific Northwest National Laboratory. Original written by Tom Rickey. Note: Content may be edited for style and length.

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