Innate immune responses to a single session of sprint interval training.

Sprint interval training (SIT) is a potent stimulus for physiological and metabolic adaptations comparable with those induced by traditional "aerobic" endurance training. There has been a great deal of recent research on SIT, which may lead to increased use of this type of training. The purpose of the present study was to determine the acute effects of SIT on aspects of innate immunity not previously researched in this context. Nine males completed 1 SIT and 1 resting control trial in a crossover design. Blood and saliva samples were obtained at pre-, post-, and 30 min postexercise to measure blood neutrophil oxidative burst activity (OBA) in addition to saliva secretary IgA (s-IgA) and lysozyme. SIT induced a significant depression of neutrophil fMLP-stimulated OBA (-30% for the 30-min postexercise time point, p < 0.01), PMA-stimulated OBA (-14% for the postexercise time point, -21% for the 30-min postexercise time point, p < 0.01), and bacterial-stimulated degranulation (-23% for the postexercise time point, -32% for the 30-min postexercise time point, p < 0.01) but not fMLP-then-PMA-stimulated OBA, saliva lysozyme, or s-IgA concentrations or secretion rates (p > 0.05). The main novel finding of the present study is that a single session of SIT causes significant exercise-induced immunodepression of some neutrophil functions but mucosal immunity was not depressed.