Match the signals activated by free radical production during exercise with their function.

• A. Nuclear factor kappa B - it plays a key role in the expression of several muscle proteins and antioxidant enzymes; Mitogen activated kinase - it plays a key signaling role in the production of new mitochondria
• B. Nuclear factor kappa B - promotes fat oxidation; Mitogen activated kinase - inhibits mitochondria
• C. Nuclear factor kappa B - regulates glycolysis; Mitogen activated kinase - controls calcium release
• D. Nuclear factor kappa B - causes muscle atrophy; Mitogen activated kinase - suppresses mitochondria

Answer: (A)

Free radical production during exercise serves as a signaling cue that activates key regulatory pathways in muscle. NF-κB, a transcription factor sensitive to oxidative stress, is turned on and promotes the expression of various muscle proteins and antioxidant enzymes. This helps rebuild and strengthen muscle while boosting the cell’s defenses against reactive oxygen species. On the other hand, mitogen-activated protein kinase (MAPK) pathways respond to the same ROS signals and mechanical stress to drive mitochondrial biogenesis, increasing the number of mitochondria and the muscle’s oxidative capacity. Together, these responses reflect how ROS can guide adaptation rather than cause harm in the context of regular exercise.

That matches the idea that NF-κB supports production of muscle proteins and antioxidant enzymes, while MAPK signaling contributes to the creation of new mitochondria. The other described roles—such as promoting fat oxidation, inhibiting mitochondria, regulating glycolysis, controlling calcium release, or causing muscle atrophy—are not the primary adaptive functions linked to ROS signaling from exercise in this context.