Normal exercise is possible if hemoglobin is greater than which value?

• A. Greater than 12 g/dL
• B. Greater than 8 g/dL
• C. Greater than 9 g/dL
• D. Greater than 10 g/dL

Answer: (B)

Oxygen delivery to muscles depends on how much hemoglobin is available to carry oxygen. When hemoglobin is at the low end of what’s considered normal, tissues still receive enough oxygen to support typical activity, so normal exercise is feasible. If hemoglobin drops further, the body can’t deliver oxygen efficiently enough for ordinary exertion, leading to increased fatigue and shortness of breath.

Thus, the best choice reflects the point at which oxygen-carrying capacity is just sufficient to permit normal activity—the lower end of the normal range. Values higher than this still allow normal exercise, but they aren’t the minimal threshold.