Blood Chemistry Changes During an Ultra-marathon Competition

Abstract

PURPOSE: The purpose for this study is to assess venous electrolyte changes in ultra-marathon athletes. There are few studies on ultra-endurance activities reporting blood parameter changes and their potential effects, and those that are published have conflicting results. We speculate that plasma fluid shifts and the metabolic demands occurring during an ultramarathon will result in significant changes in metabolites, electrolytes, hemoglobin and hematocrit levels that could be of risk to the runner’s health. METHODS: Consent was obtained from each participant the day before the Saint Sebastian 100, November 2017. The event was conducted over a repeated ten-mile loop in the Saint Sebastian Preserve, Florida. The environmental conditions were moderately warm and humid. Races consisted of 50 kilometers, 50 miles and 100-mile distances. Blood samples were collected from the antecubital vein with 1 cc insulin syringes. Blood was analyzed with an i-STAT Handheld blood analyzer with the CHEM8+ cartridge (© Abbot Point of Care, Princeton, NJ). Paired sample t-tests were used to compare pre and post-race values (mean±SD), p≤0.05, number of participants n=12. RESULTS: Significant changes pre to post race were found in the following: Potassium (3.97 ± 0.19, 4.27±0.48 (mmol/L), t(11)=-2.31; p=0.04); BUN (16.75±8.18, 25.25±7.28 (mg/dl), t(11)=-4.89; p<0.001); Creatinine (0.85±0.13, 1.48±0.68 (mg/dl), t(11)=-3.31; p=0.007); Hematocrit (44.75±3.41, 47.25±3.67 (%), t(11)=-4.38; p=0.001); Hemoglobin (15.217±1.15, 16.07±1.24 (g/dl), t(11)=-4.35; p=0.001); Sodium and glucose did not show significant changes pre to post race. Significant changes were not noted between different race distances. CONCLUSION: The results from this study show dehydration, muscle catabolism, and increased stress upon kidney function in the ultra-marathon athletes. These results demonstrate that electrolytes are altered post ultramarathon. The severity of these alteration is not known as various studies show opposing results. More research is needed to determine the extent of these changes and why some studies show changes when others do not. These changes could be of clinical significance to the runner’s health or possibly through training they have adapted to these stressful alterations.