Chronic exercise reduces illness severity, decreases viral load, and results in greater anti-inflammatory effects than acute exercise during influenza infection.
BACKGROUND
It is assumed that moderate exercise may improve resistance to infection and reduce inflammation, but there are limited data to support this assumption in an infection model.


METHODS
BALB/cJ mice were assigned to the following groups: no exercise (NON-EX), 1 session of acute exercise (A-EX), or chronic exercise for approximately 3.5 months (C-EX). Mice were infected with influenza (C-EX mice infected at rest; A-EX mice infected 15 min after exercise).


RESULTS
C-EX mice demonstrated the lowest severity of infection, assessed by body weight loss and food intake. There was less virus in the lungs at day 5 after infection in C-EX and A-EX mice compared with NON-EX mice (P = .02) and less virus at day 2 after infection only in C-EX mice (P = .07). Soon after infection (day 2), interleukin 6 (IL-6), monocyte chemoattractant protein 1 (MCP-1), macrophage inflammatory protein 1beta, and tumor necrosis factor alpha in the bronchoalveolar lavage (BAL) fluid were lower in C-EX and A-EX than in NON-EX mice. At day 5 after infection, the BAL fluid from C-EX (but not A-EX) mice had less IL-6, interleukin 12p40, granulocyte colony-stimulating factor, keratinococyte-derived chemokine, and MCP-1 than that from NON-EX mice. A trend toward reduced immunopathologic response was found in C-EX mice.


CONCLUSIONS
Chronic exercise resulted in reduced symptoms, virus load, and levels of inflammatory cytokine and chemokines. Acute exercise also showed some benefit, which was limited to the early phase of infection.
Sim
Young-Je
YJ
Department of Immunobiology, College of Human Sciences, Iowa State University, Ames, Iowa 50011-1160, USA. mkohut@iastate.edu
Yu
Shan
S
Yoon
Kyoung-Jin
KJ
Yoon
Kyoungjin J
KJ
Loiacono
Christie M
CM
Kohut
Marian L
ML
D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000276:immunology; D018925:Chemokines / Q000032:analysis; D004195:Disease Models, Animal; D005081:Exercise Therapy / Q000379:methods*; D006801:Humans; D009980:Influenza A virus; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009976:Orthomyxoviridae Infections / Q000276:immunology* / Q000503:physiopathology / Q000517:prevention & control*; D010809:Physical Fitness; D012720:Severity of Illness Index; D019562:Viral Load
D018925:Chemokines