Effects of training on metabolic responses and performance capacity in Streptococcus pneumoniae infected rats.

These experiments were designed to study whether endurance training prior to Streptococcus pneumoniae infection in rats (N = 15 in each group) alters lethality, performance capacity, and related energy metabolism. A 5-d.wk-1, 4-wk-long pre-infection training program with gradually increasing swim time caused no protection from lethality (48% at 72 h post-inoculation), but performance capacity increased by 68% (P less than 0.01). The catabolic responses as evidenced by changes in insulin and glucagon levels were less pronounced. Mobilization of free fatty acids increased twofold (P less than 0.01), and improved ketonemic adaptation (47%, P less than 0.01) occurred with concomitant saved carcass, liver, and skeletal muscle glycogen contents (P less than 0.01). This shift from carbohydrate toward fat metabolism during exercise as a result of training was also reflected by 21% lower (P less than 0.01) blood lactate levels. It was concluded that the improved metabolic status, characterizing the trained as compared with the untrained host, is partly preserved during ongoing acute gram-positive bacterial infection.