Carbohydrate ingestion reduces skeletal muscle acetylcarnitine availability but has no effect on substrate phosphorylation at the onset of exercise in man

Abstract

This study investigated the effect of reduced acetylcarnitine availability on oxidative metabolism during the transition from rest to steady-state exercise. Eight male subjects completed two randomised exercise trials at 68% of the peak rate of O2 uptake (̇VO2,peak). On one occasion subjects ingested 1 g (kg body mass)-1 glucose 75 min prior to exercise (CHO), whereas the other trial acted as a control (CON). Muscle samples were obtained pre- and 75 min post-ingestion, and following 1 and 10 min of exercise. Plasma glucose and insulin were elevated (P < 0.05), and plasma free fatty acids (FFA) were lower at the onset of exercise in CHO. Acetylcarnitine (CON, 4.8 ± 1.8; CHO, 1.5 ± 0.9 mmol (k..