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.
Key words
ultra-endurance - skin-fold thickness - anthropometry - body fat
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Correspondence
Dr. B. Knechtle
Gesundheitszentrum
Vadianstr. 26
9001 St. Gallen
Switzerland
Telefon: +41/71/226 82 82
Fax: +41/71/226 82 72
eMail: beat.knechtle@hispeed.ch