Abstract

Twenty-three male Black African and 23 male Caucasian subjects, ascertained as sedentary, participated in this study designed to determine whether there were differences in skeletal muscle histochemical and biochemical characteristics between racial groups. Muscle fiber type proportions (I, IIa, and IIb), fiber areas and activities of several enzyme markers of different energy metabolic pathways were determined from a biopsy of the vastus lateralis. Results indicated that Caucasians had a higher percent type I (8) and a lower percent type IIa (6.7) fiber proportions than Africans. No significant difference were observed between the two racial groups in the type IIb fiber proportion or in the three fiber type areas. Enzymes catalyzing reactions in phosphagenic (creatine kinase (CK)) and glycolytic (hexokinase (HK), phosphofructokinase (PFK), and lactate dehydrogenase (LDH)) metabolic pathways had significantly higher activities (about 30-40) in the Black African group than in the Caucasian group. No significant difference was noted in the activities of oxidative enzymes (malate dehydrogenase (MDH), oxoglutarate dehydrogenase (OGDH), and 3hydroxyacyl-COA dehydrogenase (HADH)). Consequently, the PFK/OGDH ratio was significantly elevated in Africans. The racial difference observed between Africans and Caucasians in fiber type proportion and enzyme activities of the phosphagenic and glycolytic metabolic pathways may well result from inherited variation. These data suggest that sedentary male Black individuals are, in terms of skeletal muscle characteristics, well endowed for sport events of short duration. Verf.-Referat