SKELETAL-MUSCLE GLYCOLYTIC AND OXIDATIVE ENZYME CAPACITIES ARE DETERMINANTS OF INSULIN SENSITIVITY AND MUSCLE COMPOSITION IN OBESE WOMEN

Regional fat distribution is an important determinant of insulin resis tance in obesity. In the current study, the relationship between skele tal muscle insulin sensitivity, mid-thigh muscle composition, and the metabolic profile of muscle was investigated. Muscle composition was a ssessed by computed tomography of the mid-thigh, and by activities of marker enzymes of aerobic-oxidative and glycolytic pathways and muscle fiber typing using biopsies of the vastus lateralis muscle. Muscle wi th reduced Hounsfield attenuation on computed tomography scans was inc reased in proportion to obesity, and was strongly related to insulin r esistance, reduced muscle oxidative capacity, and increased anaerobic and glycolytic capacities by muscle. These findings suggest that as pa rt of its expression of insulin resistance, skeletal muscle of obese i ndividuals is also poorly equipped for substrate oxidation and manifes ts increased storage of fat.