Journal of Sports Science and Medicine
Journal of Sports Science and Medicine
ISSN: 1303 - 2968   
Ios-APP Journal of Sports Science and Medicine
Androit-APP Journal of Sports Science and Medicine
from September 2014
©Journal of Sports Science and Medicine (2007) 06, 401 - 407

Research article
Running 338 Kilometres within Five Days has no Effect on Body Mass and Body Fat But Reduces Skeletal Muscle Mass – the Isarrun 2006
Beat Knechtle1, , Götz Kohler2
Author Information
1 Gesundheitszentrum St. Gallen, St. Gallen, Switzerland
2 Division of Biophysical Chemistry, Biozentrum, University of Basel, Switzerland

Beat Knechtle
✉ Facharzt FMH für Allgemeinmedizin, Gesundheitszentrum St. Gallen, Vadianstrasse 26, 9001 St. Gallen, Switzerland
Publish Date
Received: 19-02-2007
Accepted: 24-05-2007
Published (online): 01-12-2007
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We investigated the change of body composition in ultra- endurance runners during a multi-stage ultra-endurance run, the Isarrun 2006 in Bavaria, Germany, where athletes had to run 338 km within 5 days. Body mass, skin fold thicknesses and circumferences of extremities were measured in 21 well-experienced extreme endurance male runners (mean ± SD, 41.5 ± 6.9 years, 72.6 ± 6.4 kg, 178 ± 5 cm, BMI 23.0 ± 2.0 kg·m-2), who finished mainly within the first half of the ranking, in order to calculate skeletal muscle mass and body fat mass to prove changes after the race. Body mass and calculated fat mass did not change significantly (p>0.05), but, calculated skeletal muscle mass decreased significantly (p<0.05) by 0.63 ± 0.79 kg by the end of the race. The most apparent decline (p<0.01) of the calculated skeletal muscle mass was during the first stage, and no changes were observed during the last 4 stages. We conclude, that a multi- stage ultra-endurance run over 338 km within 5 days leads to no changes of body mass or body fat mass, but a statistically significant decrease of skeletal muscle mass of 0.63 ± 0.79 kg by the end of the race in well-trained and well-experienced ultra-endurance runners. The change of skeletal muscle mass has to be evaluated in further studies at ultra-endurance races with suitable methods to detect changes in hydration status and water metabolism.

Key words: Body composition, anthropometry, ultra-running, stage race, fat mass, ultra-endurance

           Key Points
  • Ultra-runners at the Isarrun 2006 suffered no loss of body mass.
  • Skeletal muscle mass decreased highly significantly during the first stage but no significant changes of skeletal muscle mass were observed during the following 4 stages of the Isarrun 2006.
  • Body fat mass remained stable during the Isarrun 2006.
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