Effect of exercise intensity on cerebrospinal fluid interleukin-6 concentration during recovery from exhaustive...

The purpose of this study was to investigate the possible role of moderate and strenuous swimming training on plasma and cerebrospinal fluid (CSF) IL-6 (interleukin-6) levels during recovery from exhaustive exercise in rats. Wistar rats were divided into three groups: sedentary control (C), moderately trained (MT) and strenuously trained (ST). MT rats underwent swimming exercise for one hour/day and 5 days/week for 8 weeks. Animals in the ST group began swimming with 1 h/day and swimming duration was progressively increased by 30 min/wk, reaching 2.5 h/day by week 4 and stayed constant for an additional 4 weeks. After all animals underwent an acute exhaustive swimming exercise, animals were divided into 3 groups, and decapitated immediately, 24 and 48 hours after exhaustion to obtain tissue samples. Muscle citrate synthase activity, plasma and CSF IL-6 levels were determined. The citrate synthase activity was found to be higher in MT and ST groups compared to the C group. Although plasma IL-6 levels were found unaltered among all groups, the CSF IL-6 concentration was found to be increased 24 hours after exhaustive exercise of the ST group. We conclude that exercise training intensity is an important factor determining cerebrospinal IL-6 concentration after exhaustive exercise.