Cardiorespiratory and metabolic fitness indicators in novice volleyball trainees: effect of 1-week antioxidant supplementation with N-acetyl-cysteine/zinc/vitamin C

Abstract

Objectives This study aimed to determine the effect of 7-day dietary supplementation of N-acetylcysteine (NAC)/zinc/vitamin C on the time-to-exhaustion (TTE), the cardiorespiratory fitness (CRF) index, and metabolic indicators. Methods This study enrolled volleyball student trainees (n = 18 men) who took NAC/zinc/vitamin C (750 mg/5 mg/100 mg) for 7 days at Jouf University, Saudi Arabia. The CRF index and TTE were determined. Serum concentrations of metabolic regulators (insulin, betatrophin, and hepatocyte growth factor), biomarkers of cellular damage/hypoxia, and indicators of lipid and glycemic control were measured. Results Supplementation improved the TTE and CRF index, and lowered cytochrome c, C-reactive protein, hypoxia-inducible factor-1α (HIF-1α), total cholesterol, insulin, and glycated hemoglobin values. Before and after supplementation, the CRF index was negatively correlated with body mass index and positively correlated with the TTE. Before supplementation, the CRF index was positively correlated with betatrophin concentrations, and hepatocyte growth factor concentrations were positively correlated with betatrophin concentrations and negatively correlated with the homeostasis model assessment of insulin resistance index. After supplementation, the CRF index was negatively correlated with HIF-1α concentrations and metabolites. Additionally, the TTE was negatively correlated with HIF-1α, cytochrome c, and triacylglycerol concentrations. Conclusion Supplementation of NAC/zinc/vitamin C improves metabolic and CRF performance.

Vitamin C and glutathione supplementation: a review of their additive effects on exercise performance

“…They concluded that vitamin C supplementation increased plasma GSH levels, thereby enhancing the protective antioxidant effect in the blood [ 82 ]. Ascorbate administration to newborn rats with glutathione deficiency has been shown to reduce toxicity and mortality rates and increase tissue and mitochondrial glutathione levels [ 83 ].…”

“…The effects of this supplementation on time-to-exhaustion (TTE), cardiorespiratory fitness (CRF) index, and metabolic indicators were investigated. The results indicated significant improvements in TTE and CRF following one-week supplementation with the combination of substances [ 83 ]. Although limited, previous studies have suggested that the combined supplementation of vitamin C and glutathione may exhibit additive effects compared to individual supplementation.…”