Exercise-Unresponsive Hyperglycemia: The Concept of "Muscle Angina"

Description This work introduces the concept of “Muscle Angina” as a conceptual framework to explain exercise-unresponsive hyperglycemia. It proposes that, under chronic metabolic stress, skeletal muscle may undergo functional metabolic distress leading to adaptive withdrawal from effective glucose uptake despite preserved perfusion and physical effort. By reframing skeletal muscle as an active metabolic decision-making organ rather than a passive responder to exercise, this narrative challenges the assumption that physical activity universally corrects hyperglycemia. The concept draws on physiological observations across life stages and clinical states—including infants, toddlers, and bed-ridden individuals—where glycemic regulation occurs without active exercise, highlighting that failure of exercise to lower glucose reflects disturbed muscular metabolic responsiveness rather than lack of effort. This contribution is intended as a conceptual and educational perspective only, without diagnostic criteria, quantitative thresholds, or therapeutic pathways.