The biochemistry of runners in a 1600 km ultramarathon

Objective-To investigate biochemical changes related to muscle breakdown, h epatic damage, hyponatraemia, and a number of other variables in the serum of participants in a 1600 km ultramarathon run. Methods-Blood samples were obtained fi om nine participants (seven men, two women) in a 1600 km foot race before, after 4 and 11 days of running, and at the conclusion of the event. Samples were analysed by standard methods a nd results corrected, where appropriate, for changes in plasma volume. Results-Significant (p<0.05) increases in the following variables were foun d during or at the conclusion of the event: plasma volume, sodium, chloride , urea, alkaline phosphatase, gamma-glutamyltransferase, alanine aminotrans ferase, aspartate aminotransferase, lactate dehydrogenase, creatine kinase, bilirubin, total protein, albumin, glucose, calcium, and phosphate. Signif icant (p<0.05) decreases in the following variables were found during or at the conclusion of the event: globulin, uric acid, and cholesterol. No chan ge occurred in serum potassium, bicarbonate, creatinine, and triglycerides. Conclusion-A wide range of biochemical perturbations occur during ultramara thon running but a number of variables remain within normal limits despite severe physical stress. Large increases in plasma volume occur, and hyponat raemia is rare in events of this duration. The time course of increases in enzymic indicators of muscle damage indicates that duration of running is n ot the sole determinant of such increases. This study provides indirect evi dence of possible hepatic damage during prolonged exercise and an increase in serum calcium both of which warrant further investigation.