Int J Sports Med 2009; 30(3): 163-167
DOI: 10.1055/s-0028-1104585
Physiology & Biochemistry

© Georg Thieme Verlag KG Stuttgart · New York

An Ultra-cycling Race Leads to no Decrease in Skeletal Muscle Mass

B. Knechtle 1 , 2 , A. Wirth 1 , P. Knechtle 1 , T. Rosemann 2
  • 1Gesundheitszentrum, St. Gallen, St. Gallen, Switzerland
  • 2Institute of General Practice and Health Services, University of Zurich, Zurich, Switzerland
Further Information

Publication History

accepted after revision September 4, 2008

Publication Date:
06 February 2009 (online)

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Abstract

Ultra-endurance races lead to an enormous energy deficit, and a decrease in body mass in the form of fat mass as well as skeletal muscle mass can be found. The decrease in skeletal muscle mass has been demonstrated in ultra-runners. We investigated therefore, in an ultra-cycling race, whether ultra-cyclists also suffered a decrease in body mass and whether we could find changes in skeletal muscle mass and/or fat mass. The anthropometric method was used to determine body mass, skeletal muscle mass and fat mass in 28 male Caucasian, non-professional, ultra-cyclists before and after a 600 km ultra-cycling race. In order to quantify hydration status, we measured total body water, haematocrit, plasma sodium and urinary specific gravity. In addition, plasma urea was determined as a marker of protein catabolism. Body mass as well as fat mass decreased highly significantly (p<0.01) whereas skeletal muscle mass did not change (p>0.05). The post race minus pre race difference (Δ) in body mass was associated with Δ fat mass (p<0.05). Urea increased highly significantly (p<0.01); however Δ urea was not associated with Δ skeletal muscle mass. We concluded that ultra-cycling in contrast to ultra-running leads to no reduction in skeletal muscle mass.