BLOOD GLUTATHIONE STATUS FOLLOWING DISTANCE RUNNING

In 12 moderately trained subjects reduced glutathione (GSH) and oxidiz ed glutathione (GSSG) as well as thiobarbituric acid reactive substanc es (TBARS) were measured in the blood before and during the first two hours and first two days after a 2.5-h run. The participants covered b etween 19 and 26 km (20.8 +/- 2.5 km, mean +/- SD), The running speed was between 53 and 82% of the speed at which blood lactate concentrati on reached 4 mmol/L lactate (67.9 +/- 8.2%, mean +/- SD) assessed duri ng a previously performed treadmill test. Blood samples were collected Ih before, immediately before, immediately after, 1 and 2 h after, as well as 1 and 2 days after the run. Immediately after exercise GSH wa s significantly decreased (p < 0.01) and GSSG significantly increased (p < 0.01). In all subjects the ratio of GSH to GSSG showed a marked d ecline to 18 +/- 4% (mean +/- SD) of the pre-exercise values (p < 0.01 ). One hour later the mean GSH and GSSG values returned to baseline. H owever, there were considerable inter-individual differences. In some subjects the GSH/GSSG ratio overshot the pre-exercise levels, in other s the ratio remained low even two hours after exercise. Compared with the pre-exercise values TBARS concentrations did not change significan tly at a ny time point after exercise. The findings suggest that after prolonged exercise in moderately trained subjects a critical shift in the blood glutathione redox status may be reached. The changes observ ed were generally short-lived, the duration of which may have depended on the relative importance of reactive oxygen species generation by t he capillary endothelial cells and neutrophil and eosinophil granulocy tes after the end of exercise.