title: Male ironman triathletes lose skeletal muscle mass.
abstract: We investigated whether male triathletes in an Ironman triathlon lose body mass in the form of fat mass or skeletal muscle mass in a field study at the Ironman Switzerland in 27 male Caucasian non-professional Ironman triathletes. Pre- and post-race body mass, fat mass and skeletal muscle mass were determined. In addition, total body water, hematological and urinary parameters were measured in order to quantify hydration status. Body mass decreased by 1.8 kg (p< 0.05), skeletal muscle decreased by 1.0 kg (p< 0.05) whereas fat mass showed no changes. Urinary specific gravity, plasma urea and plasma volume increased (p< 0.05). Pre- to post-race change (Delta) in body mass was not associated with ? skeletal muscle mass. Additionally, there was no association between Delta plasma urea and Delta skeletal muscle mass; Delta plasma volume was not associated with Delta total body water (p< 0.05). We concluded that male triathletes in an Ironman triathlon lose 1.8 kg of body mass and 1 kg of skeletal muscle mass, presumably due to a depletion of intramyocellular stored glycogen and lipids.
authors.affiliation: Facharzt FMH fur Allgemeinmedizin, Gesundheitszentrum St. Gallen, Vadianstrasse 26, 9001 St. Gallen, Switzerland. beat.knechtle@hispeed.ch
authors.forename: Beat
authors.initials: B
authors.lastname: Knechtle
authors.forename: Barbara
authors.initials: B
authors.lastname: Baumann
authors.forename: Andrea
authors.initials: A
authors.lastname: Wirth
authors.forename: Patrizia
authors.initials: P
authors.lastname: Knechtle
authors.forename: Thomas
authors.initials: T
authors.lastname: Rosemann
mesh_terms: D050154:Adiposity / Q000502:physiology; D000328:Adult; D000886:Anthropometry; D056352:Athletes; D001823:Body Composition / Q000502:physiology*; D001834:Body Water / Q000502:physiology; D006400:Hematocrit; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology*; D010953:Plasma Volume / Q000502:physiology; D012964:Sodium / Q000097:blood; D013046:Specific Gravity; D013177:Sports / Q000502:physiology*; D014508:Urea / Q000097:blood; D014556:Urine / Q000737:chemistry; D015431:Weight Loss; D044465:White People
chemical_list: D014508:Urea; D012964:Sodium