Hematological and metabolic changes after a 6-day ultramarathon on indoor cycle and treadmill

Abstract

Ultra-endurance events may induce biological changes as a consequence of intense muscle stress and hormonal fluctuations. Two ultra-endurance athletes, one on treadmill, the other on a home trainer pinion, have attempted to break world records for greatest distance covered over 6 days in Paris on January 4–10, 2015 (“six extreme days”). We analyzed the hematological, hormonal and biochemical changes. Hematological, biochemical, hormonologic, metabolic and specific to oxidative stress analysis were conducted on fresh and frozen blood samples collected a week before (D-7), 30 minutes (D6) and 2 days (D8) after the event for both sportsmen. Periods of waking/sleep, cardiovascular data (pulse, saturation) and developed efforts (distance, speed) were monitored throughout the event. Hemoglobin, hematocrit and iron parameters (serum iron, ferritin, transferrin saturation coefficient) were found lower on D6, after 2750 km cycling or 713 km running, than on D-7 (hemoglobin decreased from 15.2 g/dl before the event to 13.3 g/dl just after). They start to increase back on D-8. Leukocytes (6.5 to 9.4 G/l between D-7 and D-6), haptoglobin (tripled between D-7 and D-8, from 1 to 3 g/l), liver enzymes, Creatine Phosphokinase, troponin, Brain Natriuretic Peptide and uric acid rose during the event before going back down on D8 without however reaching back initial levels. The observed transient anemia is multifactorial, inflammatory, iron deficiency but without here any element for hemolysis. Hepatic cytolysis and heart stress are commonly encountered [1] . No study however focuses on oxidative stress enzymes (glutathione, lipid peroxidation products, activation of xanthine oxidase) after such a long effort, for which mobilization of leukocytes and increased uric acid (antioxidant) are indirect markers [2] . Data from this exploration should help enhancing our understanding of the impact of very prolonged effort on the oxidative stress chain, and paves the way for potential improvement in the training methods of athletes.