Metabolic and morphological profile in skeletal muscle of healthy boys and girls. Issue 16 (19th August 2022)

• Record Type: Journal Article
• Authors: Esbjörnsson, Mona; Norman, Barbara; Dahlström, Monica; Gierup, Jan; Jansson, Eva
• Is Part Of: Physiological reports. Volume 10:Issue 16(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-08-19
• Subjects: age -- children -- cross‐sectional area -- fiber types -- metabolic enzymes -- sex; Physiology -- Periodicals; 571
• DOI: 10.14814/phy2.15414
• Languages: English
• ISSNs: 2051-817X

Abstract

Abstract: It was hypothesized that the typical adult pattern of higher glycolytic capacity in skeletal muscle of males compared to females is not observed in children and that fiber cross‐sectional area (CSA) is a determinant of glycolytic capacity in children. Biopsies were performed in vastus lateralis in 9–12 years‐old healthy boys and girls ( N = 27). Fiber types were classified by myofibrillar ATPase staining and CSA was measured using planimetry. Citrate synthase (CS) and lactate dehydrogenase (LD) were analyzed using fluorometric and spectrophotometric methods. There was no significant difference between boys and girls in CS activity (0.45 ± 0.1 μkat g −1 dry muscle in boys and 0.42 ± 0.1 in girls) or LD activity (24 ± 6 μkat g −1 dry muscle in boys and 25 ± 7 in girls). CSA did not differ between boys and girls. CS was inversely related to type I CSA ( r = −0.62, p < 0.001) and LD was directly related to type IIA ( r = 0.63, p < 0.001) and type IIB CSA ( r = 0.72, p < 0.001). CSA was a significant determinant of CS and LD, even after adjusting for sex and relative fiber type area in multiple regression analysis. This suggests that the typical adult pattern of higher muscle glycolytic capacity in males than in females, as estimated by LD activity, was not observed in children. Sex‐specific patterns in glycolytic capacity thus appear to develop during the transition from childhood to adulthood. In addition, fiber CSA was a strong determinant of both muscle glycolytic and oxidative capacity in children, regardless of sex. Abstract : No sex difference was found in skeletal muscle lactate dehydrogenase (LD) activity in 10 years old healthy children. This suggests that the typical adult pattern of higher muscle glycolytic capacity in males than in females develops during the transition from childhood to adulthood. In addition, muscle fiber cross‐sectional area (CSA) was a statistical determinant of muscle LD activity in the children, supporting old data showing that animal size was a determinant of muscle LD activity.