Abstract
BACKGROUND: Nicotinamide adenine dinucleotide (NAD+), nicotinamide adenine dinucleotide phosphate (NADP+), and their reduced forms (NADH and NADPH) are the vital cofactors for most cellular oxidation/reduction reactions and therefore influence most critical pathways in cellular metabolism. This study aimed to predict the trends of age-related changes in erythrocyte NAD+ and NADP+ concentrations in elite athletes compared to untrained controls and to assess whether life-long physical training stimulates favorable adaptations in erythrocyte NAD(P)+ concentrations. METHODS: Erythrocyte concentrations of NAD+ and NADP+ were measured in 68 elite endurance runners (20-81 years), 58 elite sprinters (21-90 years), and 62 untrained individuals (20-68 years). Linear regression analyses were performed to estimate longitudinal relationships and cross-sectional rates of change between age and erythrocyte NAD+ and NADP+ levels. One-way analysis of variance was used to determine differences between the studied groups. RESULTS: In all three groups, the erythrocyte NAD+ and NADP+ concentrations significantly decreased with advancing age, suggesting gradual deterioration of NAD-related regulatory functions in older individuals. However, the concentration of erythrocyte NAD(P)+, regardless of age category, was higher in the athletic groups compared to less active controls. CONCLUSIONS: Our research shows that systematic sports participation, especially of a sprint-oriented nature, can be treated as a natural and effective strategy promoting cellular NAD(P)+ anabolism and thus cells' energy and redox metabolism. TRIAL REGISTRATION: The study was retrospectively registered in the clinical trials registry on 2021-11-09 (NCT05113914).