Document Type : Research Paper
Authors
1
Department of Exercise Physiology, Faculty of Sport Sciences, University of Isfahan, Isfahan, Iran
2
Faculty of Sport Sciences, University of Isfahan, Isfahan, Iran
3
Department of Medicine, Faculty of Institute for Physical Activity and Nutrition, University of Deakin, Geelong, Australia
Abstract
Extended Abstract
Background and Purpose
Aging is characterized by a decline in antioxidant capacity and a concomitant rise in oxidative stress, which collectively contribute to cellular damage and the advancement of age-related disorders. High-intensity interval training (HIIT) has been demonstrated to enhance antioxidant defenses by upregulating enzymatic activity and improving mitochondrial function. However, the excessive reactive oxygen species (ROS) produced during intense exercise may exert adverse effects. Coenzyme Q10 (CoQ10), a vital endogenous antioxidant integral to mitochondrial electron transport and energy metabolism, also diminishes with age, potentially heightening susceptibility to oxidative damage. While the independent benefits of HIIT and CoQ10 supplementation have been established, their combined effects in older populations remain underexplored. This study aimed to evaluate whether CoQ10 supplementation potentiates antioxidant adaptations and aerobic capacity in response to HIIT among older adults.
Materials and Methods
This randomized, double-blind, placebo-controlled clinical trial with a semi-experimental pretest-posttest design enrolled 38 healthy elderly individuals aged 65–75 years. Sample size calculation using G*Power 3.1 for repeated-measures ANOVA with interaction (power = 0.80, α = 0.05, effect size f = 0.25) indicated 34 participants were required; four additional subjects accounted for potential attrition. Eligible participants were recruited via public announcements in Isfahan and randomly allocated into HIIT+CoQ10 or HIIT+Placebo groups (n = 19 per group; 8 women and 11 men in each). All participants were medically cleared and classified as sedentary based on the Physical Activity Scale for the Elderly (PASE).Pre-intervention assessments included three 24-hour dietary recalls and PASE for physical activity. Cardiorespiratory fitness (VO₂peak) was assessed via the Astrand submaximal cycle ergometer test. Oxidative stress and antioxidant biomarkers—malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GPX), and total antioxidant capacity (TAC)—were quantified using standardized commercial assay kits exhibiting acceptable intra- and inter-assay variability.The HIIT intervention spanned eight weeks, with thrice-weekly sessions comprising five one-minute bouts at 80–95% of maximum heart rate (HRmax), interspersed by one-minute active recovery, alongside warm-up and cool-down phases, totaling 15 minutes per session. Intensity was progressively increased in three phases: weeks 1–3 (80–85% HRmax), weeks 4–6 (85–90% HRmax), and weeks 7–8 (90–95% HRmax). Participants ingested 100 mg/day of CoQ10 or placebo softgels with lunch; supplements were indistinguishable to preserve blinding. Adherence was monitored by capsule count and weekly reminders.Ethical approval was obtained from the University of Isfahan Ethics Committee (IR.UI.REC.1403.018), and the trial was registered with the Iranian Registry of Clinical Trials (IRCT20240310061243N1).
Results
Repeated-measures ANOVA revealed significant main effects of group (p = 0.048), time (p < 0.001), and group × time interaction (p < 0.001) for VO₂peak. Both groups exhibited significant post-intervention enhancements in aerobic capacity; however, the HIIT+CoQ10 group showed a significantly greater increase compared to the HIIT+Placebo group. For MDA, a marker of oxidative stress, analyses displayed a significant main effect of time (p < 0.001) and a significant group × time interaction (p < 0.001), with no significant main effect of group (p = 0.166). The reduction in MDA was more pronounced in the CoQ10-supplemented group, reflecting attenuated lipid peroxidation.SOD levels demonstrated no significant group effect (p = 0.325), but significant effects for time (p < 0.001) and the interaction (p < 0.001), indicating increases in both groups, with a larger elevation in the CoQ10 group. GPX activity showed significant time (p < 0.001) and group × time interaction effects (p < 0.001), but no significant group effect (p = 0.750). Improvement occurred in both groups without significant between-group differences. TAC revealed similar patterns: significant time (p < 0.001) and interaction effects (p < 0.001), but no significant group effect (p = 0.594). TAC increased post-intervention in both groups, with greater gains in the CoQ10 group.In summary, although both HIIT interventions improved aerobic capacity and antioxidant defenses significantly, CoQ10 supplementation elicited augmented enhancements in VO₂peak and selected antioxidant biomarkers, indicating a synergistic effect on physiological adaptations relevant to oxidative stress and aerobic fitness in older adults.
Conclusion
This investigation demonstrated that an eight-week HIIT regimen markedly enhances aerobic capacity and antioxidant defenses in older adults. CoQ10 supplementation further amplified these benefits, evidenced by greater decreases in MDA and increases in SOD and TAC relative to placebo control. Although GPX activity improved with training, CoQ10 did not significantly influence this parameter. These findings corroborate existing evidence on HIIT benefits and highlight a synergistic interaction when combined with CoQ10. Given the decline in VO₂peak and antioxidant capacity associated with aging, this combined approach provides a promising intervention to mitigate age-related physiological deterioration. Incorporating targeted supplementation alongside structured exercise in geriatric health programs is thus supported. Future studies should investigate dose-response relationships and long-term effects in older populations to optimize anti-aging strategies through lifestyle and nutritional interventions.
Key Words: High-Intensity Interval Training (HIIT), Coenzyme Q10, Aging, VO₂peak, Oxidative Stress
Article Message
considering the decline in aerobic capacity, elevated oxidative stress, and diminished antioxidant system efficiency with aging, a combined approach of supplementation and exercise training represents a scientifically grounded and effective strategy to counteract aging-related degeneration. The findings of this study may inform the design of future geriatric medicine, exercise, and clinical nutrition interventions.
Ethical Considerations
This study was approved by the Ethics Committee of the University of Isfahan (IR.UI.REC.1403.018), and it was registered in the Iranian Registry of Clinical Trials (IRCT) under the identifier IRCT20240310061243N1.
Authors’ Contributions
All authors contributed equally to the development and finalization of this manuscript.
Conflict of Interest
The authors declare that this research was conducted without any funding. No conflicts of interest exist that could have influenced the results or interpretation.
Acknowledgments
We sincerely thank all the elderly participants for their cooperation during this study.
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