Effects of Coenzyme Q10 Supplementation on Physical Function Adaptations to High-Intensity Interval Training in Older Adults

<b>Objectives:</b> This study investigated whether CoQ10 supplementation enhances physical adaptations to high-intensity interval training (HIIT) in muscular strength, power, and physical function in older adults. <b>Method:</b> In a double-blind, randomized controlled trial, 38 adults aged 65-75 were assigned to either a CoQ10 (Females: 8; Males: 11) or placebo (Females: 8; Males: 11) group and completed an 8-week supervised HIIT program. Lower- and upper-body strength (30s 5-repetition chair stand [5XSST], chair standing [30CST], handgrip strength [HGR/L]), balance (single-leg stand [SLS], timed up and go [TUG]), mobility (25-foot walk [25FW]), and aerobic endurance (6-minute walk [6MWT]) were assessed pre- and post-intervention. <b>Results:</b> The CoQ10 group demonstrated significantly greater improvements in 5XSST and 30CST compared to the placebo group (<i>p</i> < 0.05). Both groups showed significant within-group improvements in right and left handgrip strength, SLS, 6MWT, and TUG (all <i>p</i> < 0.001), with no significant between-group differences observed for these outcomes (<i>p</i> > 0.05). No adverse events were reported. <b>Conclusion:</b> While CoQ10 supplementation enhanced improvements in lower-body strength and power, as indicated by the greater gains in 5XSST and 30CST performance compared to the placebo, no between-group differences were observed in TUG, grip strength, or other functional outcomes. This suggests that the performance-related effects of CoQ10 may be more specific to muscular power output and fatigue resistance, rather than general mobility or balance-related tasks. These findings highlight the potential of CoQ10 as a targeted adjunct in exercise for supporting lower-body function and physical performance in older adults.