title: Carbohydrate and fat metabolism related to blood lactate in boys and male adolescents.
abstract: The half maximal constant (k (el)) of the relative rate of carbohydrate oxidation (relCHO) was individually approximated (relCHO = 100/(1 + k (el)/BLC(2)) as a function of the blood lactate concentration (BLC) in 11 pre-pubertal boys and 11 male adolescents (age: 11.6 +/- 0.1 vs. 16.4 +/- 0.2 years, height: 151.6 +/- 1.7 vs. 182.4 +/- 2.3 cm, body mass: 38.2 +/- 1.1 vs. 68.7 +/- 2.3 kg, all P < 0.001) during incremental cycle ergometry. k (el) explained 89.0 +/- 2.2 and 91.9 +/- 2.2% of the variance of the reliance on CHO in boys and adolescents respectively (both P < 0.001). No difference in k (el) [1.34 +/- 0.40 vs. 1.48 +/- 0.30 (mmol l(-1))(2)] was found between boys and adolescents. The BLC was lower (P < 0.05) in boys when relCHO was higher than 91.2 +/- 2.1 and 92.1 +/- 1.3% in boys and adolescents respectively. This seems to explain why the reliance on CHO and the BLC are independent of maturation in the moderate and heavy exercise intensity domain and the BLC but not the relCHO which is higher under severe and maximal exercise conditions in more mature subjects.
authors.affiliation: Centre for Sport and Exercise Science, Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK. rbeneke@essex.ac.uk
authors.forename: Ralph
authors.initials: R
authors.lastname: Beneke
authors.forename: Matthias
authors.initials: M
authors.lastname: Hütler
authors.forename: Renate M
authors.initials: RM
authors.lastname: Leithäuser
mesh_terms: D000293:Adolescent; D041923:Adolescent Development / Q000502:physiology*; D000367:Age Factors; D015308:Anaerobic Threshold / Q000502:physiology; D050260:Carbohydrate Metabolism / Q000502:physiology*; D002648:Child; D005080:Exercise Test; D006801:Humans; D019344:Lactic Acid / Q000097:blood*; D050356:Lipid Metabolism / Q000502:physiology*; D008297:Male; D010084:Oxidation-Reduction; D005082:Physical Exertion / Q000502:physiology; D011627:Puberty / Q000378:metabolism
chemical_list: D019344:Lactic Acid