The effects of strenuous exercise on infection with Francisella tularensis in rats

To investigate the effects of strenuous forced exercise on the course and complications of a bacterial infection and on myocardial responses and performance capacity, rats with tularemia (characterized by pyogranulomatous hepatic and splenic lesions) were exercised by swimming on days 0-6 of infection. Levels of glutamic oxaloacetic and pyruvic transaminases in plasma, densities of pyogranulomatous lesions, and bacterial counts in blood, liver, and spleen were similar in exercising and resting rats. Although a few exercising rats showed an unusual dissemination of infection, the antibody responses were similar in rest and exercise. Plasma concentrations of beta-glucuronidase, lysozyme and alpha 2-macrofetoprotein were higher with exercise, a result that indicated that more vigorous stress responses were elicited with exercise than with infection alone. Physical performance capacity was reduced by the infection, but forced daily exercise limited this reduction substantially and counteracted the myocardial protein-degrading effects of infection. Thus, exercise evoked normal training responses even during this generalized infection.