title: Substantial and reversible brain gray matter reduction but no acute brain lesions in ultramarathon runners: experience from the TransEurope-FootRace Project.
abstract: BACKGROUND
  During the extremely challenging 4,487 km ultramarathon TransEurope-FootRace 2009, runners showed considerable reduction of body weight. The effects of this endurance run on brain volume changes but also possible formation of brain edema or new lesions were explored by repeated magnetic resonance imaging (MRI) studies.
  
  
  METHODS
  A total of 15 runners signed an informed consent to participate in this study of planned brain scans before, twice during, and about 8 months after the race. Because of dropouts, global gray matter volume analysis could only be performed in ten runners covering three timepoints, and in seven runners who also had a follow-up scan. Scanning was performed on three identical 1.5 T Siemens MAGNETOM Avanto scanners, two of them located at our university. The third MRI scanner with identical sequence parameters was a mobile MRI unit escorting the runners. Volumetric 3D datasets were acquired using a magnetization prepared rapid acquisition gradient echo (MPRAGE) sequence. Additionally, diffusion-weighted (DWI) and fluid attenuated inversion recovery (FLAIR) imaging was performed.
  
  
  RESULTS
  Average global gray matter volume as well as body weight significantly decreased by 6% during the race. After 8 months, gray matter volume returned to baseline as well as body weight. No new brain lesions were detected by DWI or FLAIR imaging.
  
  
  CONCLUSIONS
  Physiological brain volume reduction during aging is less than 0.2% per year. Therefore a volume reduction of about 6% during the 2 months of extreme running appears to be substantial. The reconstitution in global volume measures after 8 months shows the process to be reversible. As possible mechanisms we discuss loss of protein, hypercortisolism and hyponatremia to account for both substantiality and reversibility of gray matter volume reductions. Reversible brain volume reduction during an ultramarathon suggests that extreme running might serve as a model to investigate possible mechanisms of transient brain volume changes. However, despite massive metabolic load, we found no new lesions in trained athletes participating in a multistage ultramarathon.See related commentary http://www.biomedcentral.com/1741-7015/10/171.
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospitals Ulm, Albert-Einstein-Allee 23, 89081 Ulm, Germany. freund-ulm@t-online.de
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Freund
authors.forename: Sonja
authors.initials: S
authors.lastname: Faust
authors.forename: Frank
authors.initials: F
authors.lastname: Birklein
authors.forename: Christian
authors.initials: C
authors.lastname: Gaser
authors.forename: Arthur P
authors.initials: AP
authors.lastname: Wunderlich
authors.forename: Marguerite
authors.initials: M
authors.lastname: Müller
authors.forename: Christian
authors.initials: C
authors.lastname: Billich
authors.forename: Markus S
authors.initials: MS
authors.lastname: Juchems
authors.forename: Bernd L
authors.initials: BL
authors.lastname: Schmitz
authors.forename: Georg
authors.initials: G
authors.lastname: Grön
authors.forename: Uwe H
authors.initials: UH
authors.lastname: Schütz
mesh_terms: D000328:Adult; D000368:Aged; D001921:Brain / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D011446:Prospective Studies; D012420:Running