*2.4. Statistical Analysis*

Sample size was estimated based on data that showed increased FMD after ARG supplementation in older adults [21]. It was estimated that 12 participants would be appropriate to detect a difference with ≥80% power at the α = 0.05 level. The Shapiro– Wilk test was used to verify the normal distribution of the data. A one-way analysis of variance was used to detect between-group differences. A two-way analysis of variance with repeated measures and Bonferroni adjustments were performed to detect time (before and after) and between-groups (placebo, CIT and CIT+GSH) differences in measures at rest and BP responses (Δ) to CPT. If significant time-by-group interactions were detected, Tukey and paired-t tests were used as post-hoc tests. Pearson's correlation coefficient was used to evaluate relationships between changes in FMD% from 0 to 4 weeks and baseline FMD, and with aortic MAP responses to CPT from 0 to 4 weeks. Independent sample t-tests were used to evaluate low (0.20), moderate (0.50), and large (≥0.80) effect sizes using Cohen's d on the changes in FMD between CIT vs. placebo, CIT+GSH vs. CIT, and CIT+GSH vs. placebo. Statistical analyses were performed using SPSS Ver26 (IBM SPSS, Armonk, NY, USA). Results are reported as the mean ± standard deviation (SD) in tables and the mean ± standard error (SE) in figures. Significance was set a priori at *p* < 0.05.
