Muscle ubiquinone in healthy physically active males

Area of Science:

• Exercise Physiology
• Biochemistry
• Muscle Metabolism

Background:

• Ubiquinone (UQ), also known as Coenzyme Q10, is crucial for mitochondrial energy production and acts as an antioxidant.
• Understanding the factors influencing UQ levels in human skeletal muscle is important for optimizing athletic performance and metabolic health.

Purpose of the Study:

• To investigate the relationship between muscle ubiquinone (UQ) content and markers of oxidative and fermentative capacity in healthy, physically active males.
• To determine if muscle UQ levels are associated with exercise performance, including the intensity at which blood lactate accumulates (WOBLA) and maximal exercise capacity (WSL).

Main Methods:

• Muscle biopsies were obtained from the vastus lateralis of 35 physically active males to analyze ubiquinone (UQ), citrate synthase activity (CS), and lactate dehydrogenase (LD).
• Subjects underwent graded cycle ergometer tests to determine WOBLA and WSL.
• Data from 11 male marathon runners were also included to assess UQ's relation to performance.

Main Results:

• Muscle UQ concentration was positively correlated with citrate synthase activity (r = 0.67, p < 0.001) and the percentage of slow-twitch (ST) muscle fibers (r = 0.60, p < 0.001).
• UQ levels were not significantly related to lactate dehydrogenase (LD) activity, indicating no link to fermentation.
• UQ was also positively associated with exercise capacity, specifically WOBLA per kilogram of body weight (r = 0.70, p < 0.001).

Conclusions:

• Muscle UQ content in humans is strongly associated with oxidative energy metabolism and exercise performance.
• The findings suggest that UQ allocation is influenced by factors related to oxygen availability and aerobic respiration, rather than fermentation.
• The dual role of UQ as a mitochondrial coenzyme (CoQ10) and a non-specific antioxidant likely contributes to its relationship with oxidative capacity and ST fibers.