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Hydrogen ions primarily limit high-intensity anaerobic exercise because they are produced in significant amounts during anaerobic glycolysis, the metabolic pathway that generates energy in the absence of oxygen. When muscles engage in high-intensity activity, the breakdown of glucose for energy leads to an accumulation of hydrogen ions, resulting in a decrease in pH within the muscle cell. This drop in pH can negatively affect the function of enzymes responsible for energy production and interfere with muscle contraction by reducing calcium sensitivity and increasing fatigue.

While nitric oxide and carbon dioxide play roles in exercise physiology, they do not primarily serve to limit high-intensity anaerobic exercise through contractile inhibition in the same manner that hydrogen ions do. Nitric oxide is involved in vasodilation and improving blood flow to tissues, which can enhance performance rather than inhibit it. Carbon dioxide production is a byproduct of aerobic metabolism and does not directly inhibit muscle contractions during high-intensity anaerobic exercise. Thus, the role of hydrogen ions stands out as the key factor in contractile inhibition during such high-intensity efforts.