The responses of plasma biochemical parameters to a 56-km race in novice and experienced ultra-marathon runners.

A number of blood biochemical parameters, including the activities of the plasma enzymes creatine kinase (CK), aspartate aminotransferase (ASAT), lactate dehydrogenase and alkaline phosphatase, were measured in 23 athletes before, and immediately after a 56-km running race. Of the 23 athletes, 18 had previously completed standard 42-km marathon or longer (up to 90-km) ultra-marathon races, whereas not one of the other five athletes had previously run in a long-distance race. After the race, plasma CK and ASAT activities had both risen at least 280% more in the novice runners despite their much slower mean running speed (9.8 +/- 0.4 vs. 13.8 +/- 0.3 hm/h). There were no other inter-group differences in the absolute levels of the other measured biochemical parameters, although the rise in plasma calcium during the race was significantly greater in the experienced marathon runners. This study shows that either higher levels of training, or previous ultra-marathon racing experience, or both, is associated with lower immediate post-exercise levels of plasma enzyme activity. This is compatible with the finding that physical training reduces post-exercise plasma enzyme levels.