title: Changes in urinary amino acids excretion in relationship with muscle activity markers over a professional cycling stage race: in search of fatigue markers.
abstract: The aim of this study was to identify the relationship between metabolic effort, muscular damage/activity indices, and urinary amino acids profile over the course of a strenuous prolonged endurance activity, as a cycling stage race is, in order to identify possible fatigue markers. Nine professional cyclists belonging to a single team, competing in the Giro d'Italia cycling stage race, were anthropometrically characterized and sampled for blood and urine the day before the race started, and on days 12 and 23 of the race. Diet was kept the same over the race, and power output and energy expenditure were recorded. Sera were assayed for muscle markers (lactate dehydrogenase, aspartate aminotransferase, and creatine kinase activities, and blood urea nitrogen), and creatinine, all corrected for plasma volume changes. Urines were profiled for amino acid concentrations, normalized on creatinine excretion. Renal function, in terms of glomerular filtration rate, was monitored by MDRD equation corrected on body surface area. Creatine kinase activity and blood urea were increased during the race as did serum creatinine while kidney function remained stable. Among the amino acids, taurine, glycine, cysteine, leucine, carnosine, 1-methyl histidine, and 3-methyl histidine showed a net decreased, while homocysteine was increased. Taurine and the dipeptide carnosine (β-alanyl-L-histidine) were significantly correlated with the muscle activity markers and the indices of effort. In conclusion, the metabolic profile is modified strikingly due to the effort. Urinary taurine and carnosine seem useful tools to evaluate the muscle damage and possibly the fatigue status on a long-term basis.
authors: Cannondale Pro-Cycling Team, Medical Board, Sesto al Reghena, Italy.
authors: Roberto
authors: R
authors: Corsetti
authors: Department of Biomedical Sciences for Health, University of Milano, Milan, Italy.
authors: Alessandra
authors: A
authors: Barassi
authors: Laboratory of Experimental Biochemistry and Molecular Biology, I.R.C.C.S. Istituto Ortopedico Galeazzi, Via Riccardo Galeazzi, 4, 20161, Milan, Italy.
authors: Silvia
authors: S
authors: Perego
authors: Laboratory of Experimental Biochemistry and Molecular Biology, I.R.C.C.S. Istituto Ortopedico Galeazzi, Via Riccardo Galeazzi, 4, 20161, Milan, Italy.
authors: Veronica
authors: V
authors: Sansoni
authors: U.O. Epidemiology, National Institute for Health, Migration, and Poverty, Rome, Italy.
authors: Alessandra
authors: A
authors: Rossi
authors: Department of Biomedical Sciences for Health, University of Milano, Milan, Italy.
authors: Clara Anna Linda
authors: CA
authors: Damele
authors: Department of Biomedical Sciences for Health, University of Milano, Milan, Italy.
authors: Gianlodovico
authors: G
authors: Melzi D'Eril
authors: Laboratory of Experimental Biochemistry and Molecular Biology, I.R.C.C.S. Istituto Ortopedico Galeazzi, Via Riccardo Galeazzi, 4, 20161, Milan, Italy.|Vita-Salute San Raffaele University, Milan, Italy.
authors: Giuseppe
authors: G
authors: Banfi
authors: Laboratory of Experimental Biochemistry and Molecular Biology, I.R.C.C.S. Istituto Ortopedico Galeazzi, Via Riccardo Galeazzi, 4, 20161, Milan, Italy. giovanni.lombardi@grupposandonato.it.
authors: Giovanni
authors: http://orcid.org/0000-0002-8365-985X
authors: G
authors: Lombardi
mesh_terms: D000328:Adult; D000596:Amino Acids / Q000097:blood / Q000652:urine*; D056352:Athletes; D001642:Bicycling / Q000502:physiology; D015415:Biomarkers / Q000652:urine*; D004734:Energy Metabolism; D005221:Fatigue / Q000378:metabolism / Q000652:urine*; D005260:Female; D006801:Humans; D007668:Kidney / Q000378:metabolism; D007677:Kidney Function Tests; D008297:Male; D009132:Muscles / Q000378:metabolism*; D010807:Physical Endurance; D014556:Urine / Q000737:chemistry*; D055815:Young Adult
chemical_list: D000596:Amino Acids; D015415:Biomarkers
keywords: Cycling stage race; Endurance; Fatigue; Muscular activity; Urinary amino acids