title: Physiologic changes during a marathon, with special reference to magnesium.
abstract: In a single case study of a moderately trained, healthy man, physiologic changes during a marathon are reported. Blood was drawn prior to the race, at 1 hour and 2 hours into the race, at the end of the race, and after 1 hour of recovery. By 1 hour into the race, norepinephrine, epinephrine, and dopamine had increased nearly nine-fold, two-fold and five-fold, respectively. After 1 hour of recovery, epinephrine had returned to the pre-race value but norepinephrine and dopamine were still elevated. Cortisol increased gradually and was more than doubled by the end of the race. It was still elevated after 1 hour of recovery. White blood cells gradually increased, reaching their maximum value at the end of the race; a four-to-five-fold increase. Thromboxane B2, which had an inverse relationship to serum magnesium, was below the pre-race value for the first 2 hours but increased nine-fold by the end of the race. Serum magnesium increased from 1.44 meq/l to 1.68 meq/l at 2 hours into the marathon, dropped to 1.07 meq/l by the end of the race, and returned to its pre-race value by 1 hour of recovery. The decrease in serum magnesium at the end of the race may be associated with increased plasma free fatty acid levels.
mesh_terms: D000328:Adult; D001774:Blood Chemical Analysis; D001798:Blood Proteins / Q000032:analysis; D006801:Humans; D007958:Leukocyte Count; D008274:Magnesium / Q000097:blood*; D008297:Male; D010807:Physical Endurance; D005082:Physical Exertion; D010949:Plasma / Q000201:enzymology; D010976:Platelet Count
chemical_list: D001798:Blood Proteins; D008274:Magnesium