Physical endurance.
We used ANOVA to estimate sequence effects, treatment effects, and period effects on physical performance outcomes. The coefficient of the interaction term between the treatment (NR, CoQ10, and placebo) and time point (before versus after) was used to estimate the treatment effect for each intervention. The impact of treatment on BW, kidney function biomarkers, and cystatin C was estimated using the method. To estimate treatment effect in the stratified analysis of physical endurance outcomes, the interaction term of activity level (active versus sedentary) and treatment or performance (poor versus good performers) and treatment were used. Treatment effects in the gender-stratified comparison were estimated using the interaction term of sex (male versus female) and treatment. We tested for possible carryover effects of the study interventions using the interaction of study period and treatment. One-way ANOVA and 2-way ANOVA were performed using GraphPad Prism 9.0. A 