title: No change of body mass, fat mass, and skeletal muscle mass in ultraendurance swimmers after 12 hours of swimming.
abstract: We evaluated whether ultraendurance swimmers suffer a change of body mass, fat mass, skeletal muscle mass, total body water and specific gravity of urine during a 12-hr swim in 12 male Caucasian ultraswimmers. Proton nuclear magnetic resonance of urine samples before and after the race was performed to detect alanine, lactate, and 3-hydroxybutyrate. The 12 swimmers achieved an average distance of 29.4 km (SD = 5.1). No statistically significant changes in body mass, fat mass, skeletal muscle mass, and total body water could be determined (p > .05), but urine gravity decreased significantly (p < .001). Two participants showed increased signals of ketone bodies after the race. In these samples, the hydroxybutyrate-creatinine ratio increased more than tenfold.
authors.affiliation: St. Gallen Health Center, St. Gallen, Switzerland. beat.knechtle@hispeed.ch
authors.forename: Beat
authors.initials: B
authors.lastname: Knechtle
authors.forename: Patrizia
authors.initials: P
authors.lastname: Knechtle
authors.forename: René
authors.initials: R
authors.lastname: Kaul
authors.forename: Götz
authors.initials: G
authors.lastname: Kohler
mesh_terms: D020155:3-Hydroxybutyric Acid / Q000378:metabolism; D000273:Adipose Tissue / Q000502:physiology*; D050154:Adiposity / Q000502:physiology*; D000328:Adult; D015992:Body Mass Index; D017079:Exercise Tolerance / Q000502:physiology*; D006801:Humans; D007657:Ketone Bodies / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology; D013550:Swimming / Q000502:physiology*; D013997:Time Factors; D016482:Urinalysis
chemical_list: D007657:Ketone Bodies; D020155:3-Hydroxybutyric Acid