Figure 3. Vastus lateralis muscle tissue citrate synthase activity levels in middle-aged (MA) participants prior to (Pre) and following 10 weeks of resistance training (Post) (A), as well as associations between the Pre-to-Post changes in this variable and muscle NAD+ concentrations (B). Data in panel (A) are presented as means±SD values. Data in panel (B) are presented as individual data points where the regression line is solid and 95% confidence interval bands are dashed. Only 15/16 middle-aged participants were assayed for citrate synthase activity levels at Pre and Post due to tissue limitations for one participant.