Identify the true statement about antioxidant groups produced by skeletal muscles.

• A. They help to prevent radical-mediated cellular damage.
• B. They promote radical-mediated cellular damage.
• C. They increase production of reactive oxygen species during exercise.
• D. They have no effect on muscle metabolism.

Answer: (C)

Antioxidant groups produced by skeletal muscles serve to keep radical species in check. When muscles contract, especially during intense or prolonged exercise, the rate of reactive oxygen species production increases. Antioxidants—like enzymes such as superoxide dismutase, catalase, and glutathione peroxidase, plus non-enzymatic members like glutathione and vitamins C and E—work to neutralize these reactive molecules. By scavenging ROS, they prevent damage to lipids, proteins, and DNA, helping maintain cellular integrity. They also participate in redox signaling that guides training adaptations. The statement that they prevent radical-mediated cellular damage best captures their role. The other ideas—that they promote damage, that they increase ROS production, or that they have no effect on metabolism—do not reflect their protective, buffering function in muscle tissue.