Which statement accurately describes NO signaling in exercise adaptations?

Which statement accurately describes NO signaling in exercise adaptations?

• A. NO has no role in signaling for mitochondrial biogenesis.
• B. NO is not involved in muscle signaling.
• C. NO only modulates blood pressure.
• D. NO participates in signaling for mitochondrial biogenesis.

Answer: (D)

Nitric oxide acts as a signaling molecule during exercise to drive muscle adaptations. As you work out, NO is produced in muscle and blood vessels, and it signals through pathways like soluble guanylate cyclase to raise cGMP and activate PKG. This signaling can help boost mitochondrial biogenesis by influencing key regulators such as PGC-1α, the master driver of creating more mitochondria and boosting oxidative capacity. NO signaling also interacts with energy-sensing pathways (like AMPK and SIRT1) and can support angiogenesis, metabolic efficiency, and better oxygen delivery to working muscles. So NO’s role isn’t limited to changing blood flow; it directly participates in the intracellular signaling that leads to more and better mitochondria in trained muscle.

The other statements miss important aspects. NO does have a signaling role in muscle beyond blood pressure modulation, so saying it’s not involved in muscle signaling isn’t accurate. And saying NO has no role in mitochondrial biogenesis ignores evidence that NO signaling can promote the expression and activity of mitochondrial biogenesis pathways.