In the early 1970s Eriksson

et al.22, 23, 24, 25 and 26 carried out a series of innovative muscle biopsy studies on small samples of 11–16 years old boys which have influenced the understanding of paediatric exercise metabolism for almost 40 years. Muscle biopsies from the lateral part of the CP-673451 datasheet quadriceps femoris revealed resting adenosine triphosphate (ATP) stores which were invariant over the age range 11.6–15.5 years. The PCr stores of the 15-year-old boys were 63% higher than those of the 11-year-old boys. The ATP stores at all ages and the PCr stores of the 15-year-old boys were not dissimilar to values others had reported in adults. Glycogen stores at rest were reported to increase by 61% from 11 years to 15 years. The concentration of ATP remained virtually unchanged following several bouts of submaximal exercise but minor reductions were reported following maximal exercise. The PCr stores gradually depleted following exercise sessions of increasing intensity. Muscle glycogen stores decreased following exercise in all age groups but the depletion was three times greater in the older boys suggesting enhanced glycolysis

selleck chemical with age.26 Eriksson et al.26 reported succinic dehydrogenase and phosphofructokinase (PFK) activity at rest in 11-year-old boys to be 20% and 50% respectively lower than they had previously reported for adults.27 Haralambie28 determined the activity of 22 enzymes involved in energy metabolism in 13–15-year-old boys and girls and in adult men Edoxaban and women and, in conflict with Eriksson’s observations, he found no significant difference in the activity of glycolytic enzymes between adolescents

and adults. He did, however, confirm his earlier observation29 of greater activity of oxidative enzymes in adolescents than in adults. Subsequently, Berg et al.30 and 31 reported glycolytic enzymes activity to be positively correlated with age and oxidative enzymes activity to be negatively correlated with age over the age range 6–17 years, in both males and females. All muscle biopsies were taken at rest. Haralambie28 and 29 reported a comparison of the resting activity of potential rate limiting enzymes of glycolysis and the tricarboxylic acid cycle, namely, PFK and isocitric dehydrogenase (ICDH). The ratio PFK/ICDH was reported to be 93% higher in adults than in adolescents at 1.633 and 0.844, respectively. A re-calculation of Berg’s data indicated a similar relationship of glycolytic and oxidative enzymes with the ratio of pyruvate kinase to fumarase varying from 3.585 in adults, 3.201 in adolescents to 2.257 in children.30 and 31 Eriksson et al.25 and 26 reported muscle lactate accumulation following exercise to increase with age and, on the basis of an ‘almost significant’ relationship between lactate accumulation in the muscles and testicular volume, they hypothesised a maturational effect on lactate production.