Do antioxidant supplements interfere with skeletal muscle adaptation to exercise training?

Area of Science:

• Exercise Physiology
• Cellular Biology
• Biochemistry

Background:

• Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are commonly believed to cause exercise-induced muscle damage.
• Emerging evidence highlights the essential role of ROS and RNS as signaling molecules in cellular adaptation to stress.

Purpose of the Study:

• To investigate the impact of antioxidant supplementation on exercise-induced ROS/RNS signaling and subsequent skeletal muscle adaptations.
• To evaluate whether antioxidant intake interferes with beneficial training responses.

Main Methods:

• Review of existing scientific literature on ROS/RNS, antioxidant supplementation, and exercise training adaptations.
• Analysis of studies examining the effects of antioxidants on endurance, high-intensity, and resistance training.

Main Results:

• Antioxidant supplementation may attenuate endurance training adaptations, including improved antioxidant capacity, mitochondrial biogenesis, and insulin sensitivity.
• High-intensity and resistance training adaptations appear more dependent on ROS/RNS signaling, with antioxidants potentially impairing responses.
• No convincing evidence supports antioxidant supplementation enhancing exercise-training adaptations.

Conclusions:

• ROS/RNS play a hormetic role in exercise adaptation, with physiological levels being beneficial and excessive levels potentially detrimental.
• Interfering with ROS/RNS signaling through antioxidant supplements may blunt crucial adaptive responses to exercise training.
• Skeletal muscle adaptation to exercise is complex, with potential redundancy in signaling pathways that may sometimes overcome antioxidant interference.