Large accumulations of carbon monoxide in the human body result in which effect?

• A. Loss of muscular power
• B. Increased stamina
• C. Enhanced vision
• D. Improved concentration

Answer: (A)

Carbon monoxide binds to hemoglobin far more readily than oxygen, forming carboxyhemoglobin, which severely reduces the blood’s oxygen-carrying capacity. With less oxygen delivered to muscles during activity, aerobic energy production drops, causing fatigue and a loss of muscular power. CO also hampers cellular respiration in mitochondria, further lowering energy available to muscles. The net effect is decreased muscle strength and weakness, especially as exposure accumulates. CO exposure does not increase stamina, enhance vision, or improve concentration; those would be expected to worsen rather than improve with rising CO levels.