Which of the following describes the effect of acute skeletal muscle contraction on inflammatory markers?

• A. Increases circulatory IL-6; inhibits TNF-α; decreases insulin resistance; stimulates lipolysis.
• B. Inhibits IL-6; increases TNF-α; increases insulin resistance; inhibits lipolysis.
• C. Decreases circulatory IL-6; stimulates TNF-α; increases insulin resistance.
• D. No change in inflammatory markers.

Answer: (A)

When contracting skeletal muscle, the muscle itself acts like an endocrine tissue and releases myokines into the circulation. Interleukin-6 is the premier myokine that rises quickly during acute exercise. In this context, the IL-6 surge promotes an anti-inflammatory environment by helping to dampen pro-inflammatory signals such as TNF-α, and it also enhances metabolic readiness by improving insulin sensitivity. At the same time, IL-6 stimulates lipolysis in adipose tissue, providing free fatty acids as fuel for the working muscles. This combination—increased IL-6, reduced TNF-α, improved insulin sensitivity, and stimulated lipolysis—matches the typical acute exercise response. The other patterns, like IL-6 lowering, TNF-α rising, worsening insulin resistance, or no change, don’t align with how the body responds to acute muscle contraction.