A, widefield microscopy images of skeletal muscle pre- (left) and post- (right) endurance training (top) and sprint interval training (bottom). Skeletal muscle NOX2 content was revealed using Alexa-Fluror 594 conjugated secondary antibody (red). Bar = 50 μm. B, mean fluorescence intensity of NOX2 within the endothelium is summarised (ET n= 7, SIT n= 8). C, mean fluorescence intensity of NOX2 within the muscle membrane is summarised (ET n= 7, SIT n= 8). The mean level of NOX2 pre-training was assigned a value of 1, and the relative intensity of NOX2 post-training was calculated.