Plasma IL-6 before and 20 min after prolonged muscular exercise for 20 min at the individual aerobic/anaerobic threshold was analyzed in patients with neuromuscular diseases and in controls. Patients were assigned to the following diagnostic categories: Controls (n=18); amyotrophic lateral sclerosis (n=7); peripheral neuropathy (n=6); muscular dystrophy (n=13); mitochondriopathy (n=3); myopathy (others) (n=3); inflammatory myopathy (n=6); mononeuropathy (n=4). The concentrations of IL-6 before exercise were 5.55+/-0.94 pg/ml, and 6.52+/-0.97 pg/ml after exercise (P=0.0001). We introduced the independent variables age, sex and diagnostic category into a stepwise multiple linear regression model. Age emerged as a significant predictor of the IL-6 ratio (IL-6 post exercise/lL-6 before exercise). The regression equation was: IL-6 ratio=0.87+0.009xage (years), R=0.33, P
