[Purpose]The aim of the study was to determine the effects of dietary CoQ10 on serum biochemical parameters, lipid peroxidation, and HSP expression in the liver and slow-twitch muscles (soleus and gastronemius deep portion) of exercise-trained rats.[Methods]A total of 42 Wistar albino rats were divided into six groups: 1) Control, 2) Coenzyme Q10 (CoQ10), 3) Chronic Exercise (CE), 4) CE + CoQ10, 5) Acute Exercise (AE), and 6) AE + CoQ10. The rats were subjected to the running test 5 days a week for 6 weeks after which CoQ10 was administered via the diet. AE (running on the treadmill until the rats were exhausted) was done on the last day[Results]The results showed no significant difference in serum glucose and liver functions in any of the groups. However, CoQ10 and exercise treatment were found to lower cholesterol and triglyceride levels. Serum and muscle malondialdehyde (MDA) levels were found to be lower in the CE and CE + CoQ10 groups compared to the control group. The highest levels of HSP60, HSP70, and HSP90 in liver and muscle were found in the AE group, and the lowest levels were found in CE + CoQ10 group. CoQ10 supplementation reduced HSP expression in both CE-and AE-trained rats (P < 0.05).[Conclusion]The results showed that CoQ10 supplementation could reduce MDA levels, protect against oxidative damage, and regulate HSP expression in CE-and AE-trained rats. CE and CoQ10 were shown to reduce oxidative stress synergistically.