Metabolic markers in sports medicine.
ABSTRACT Physical exercise induces adaptations in metabolism considered beneficial for health. Athletic performance is linked to adaptations, training, and correct nutrition in individuals with genetic traits that can facilitate such adaptations. Intense and continuous exercise, training, and competitions, however, can induce changes in the serum concentrations of numerous laboratory parameters. When these modifications, especially elevated laboratory levels, result outside the reference range, further examinations are ordered or participation in training and competition is discontinued or sports practice loses its appeal. In order to correctly interpret commonly used laboratory data, laboratory professionals and sport physicians need to know the behavior of laboratory parameters during and after practice and competition. We reviewed the literature on liver, kidney, muscle, heart, energy, and bone parameters in athletes with a view to increase the knowledge about clinical chemistry applied to sport and to stimulate studies in this field. In liver metabolism, the interpretation of serum aminotransferases concentration in athletes should consider the release of aspartate aminotransferase (AST) from muscle and of alanine aminotransferase (ALT) mainly from the liver, when bilirubin can be elevated because of continuous hemolysis, which is typical of exercise. Muscle metabolism parameters such as creatine kinase (CK) are typically increased after exercise. This parameter can be used to interpret the physiological release of CK from muscle, its altered release due to rhabdomyolysis, or incomplete recovery due to overreaching or trauma. Cardiac markers are released during exercise, and especially endurance training. Increases in these markers should not simply be interpreted as a signal of cardiac damage or wall stress but rather as a sign of regulation of myocardial adaptation. Renal function can be followed in athletes by measuring serum creatinine concentration, but it should be interpreted considering the athlete's body-mass index (BMI) and phase of the competitive season; use of cystatin C could be a reliable alternative to creatinine. Exercise and training induce adaptations in glucose metabolism which improve glucose utilization in athletes and are beneficial for reducing insulin insensitivity in nonathletes. Glucose metabolism differs slightly for different sports disciplines, as revealed in laboratory levels. Sport activities induce a blood lipid profile superior to that of sedentary subjects. There are few reports for a definitive conclusion, however. The differences between athletes and sedentary subjects are mainly due to high-density lipoprotein cholesterol (HDLC) concentrations in physically active individuals, although some differences among sport disciplines exist. The effect of sports on serum and urinary markers for bone metabolism is not univocal; further studies are needed to establish the real and effective influence of sport on bone turnover and especially to establish its beneficial effect.
Article: Serum creatine kinase activity and its relationship with renal function indices in professional cyclists during the Giro d'Italia 3-week stage race.[show abstract] [hide abstract]
ABSTRACT: To analyze the behavior of total creatine kinase (CK) and other muscular damage markers and to compare CK activity and renal function indices in professional cyclists during a 3-week stage race. Prospective, noncomparative, interventional. The athletes were recruited during the 2011 Giro d'Italia. Nine professional road cyclists from the Liquigas-Cannondale team and competing in the race. Blood samples were collected on the day before the start of the race, on day 12, and on the final day (day 22) of the race. : Creatinine and cystatin C concentrations, CK, lactate dehydrogenase (LDH), and aspartate aminotransferase (AST) activities were measured. The estimated glomerular filtration rate was calculated according to equations based on creatinine, cystatin C, or both. Creatine kinase and AST activity increased during the second part of the race, and LDH activity progressively increased during the entire course of the race. There was a negative correlation between CK activity and the delta prerace-day 12 of glomerular filtration rate, as obtained with simple cystatin C or with Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) creatinine and cystatin C equations. The effect of prolonged strenuous muscular effort on biochemical laboratory parameters in professional road cyclists was confirmed. The correlation observed between renal function and CK activity underscores that measurement of cystatin C is more accurate than creatinine alone in the evaluation of renal function and that it is unaffected by response to physical stress-induced muscular damage.Clinical journal of sport medicine: official journal of the Canadian Academy of Sport Medicine 06/2012; 22(5):408-13. · 1.50 Impact Factor