Figure 1. Flow diagram representing the stages in energy metabolism and how NAD affects each of these stages. NAD is required largely during the Krebs cycle but also is required during glycolysis and for the conversion of pyruvate at the end of glycolysis for its entry into the Krebs cycle

From

The Proposed Effects of Nicotinamide Adenine Dinucleotide (NAD) Supplementation on Energy Metabolism

Benjamin David French

American Journal of Sports Science and Medicine. 2015, 3(5), 96-107 doi:10.12691/ajssm-3-5-3