Age effects on interleukin-6 and interleukin-1β responses to endurance exercise in patients with neuromuscular diseases

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/IL-6 before exercise). The regression equation was: IL-6 ratio = 0.87 +/- 0.009 x age (years), R = 0.33, P < 0.01, simple linear regression model. All IL-1 beta concentrations were below the sensitivity of the assay (5 pg/ml). Concerning patients with neuromuscular diseases, the age associated increased IL-6 release after exercise could mean additional muscle damage. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.