The tricarboxylic acid cycle in human skeletal muscle: is there a role for nutritional intervention?

The tricarboxylic acid (TCA) cycle is essential for oxidative energy production. The expansion (anaplerosis) of the intermediates of the TCA cycle is achieved via a number of pathways, and is known to be influenced by metabolic status and nutritional and pharmacological interventions. Contraction is associated with anaplerosis in skeletal muscle, and some authors have suggested that the rate of anaplerosis can limit oxidative energy delivery. The results of more recent studies, however, are consistent with the idea that expansion of the muscle TCA intermediate pool is principally a reflection of muscle pyruvate availability, and is of little functional importance to TCA cycle flux, thereby indicating that any intervention aimed at increasing TCA intermediates expansion will be of little practical value.