Answer
When one is exercising skeletal muscle are active. In this activity, striated muscle fibers produce lactic acid and carbon dioxide. Consequently the blood pH falls and Co2 conentration [CO2] rises, slightly.
Work Step by Step
Under these circumstances the affinity of oxygen for hemoglobin decreases: this means that more oxygen dissociates from hemoglobin in the blood of one who is exercising than in the blood of one who is resting.
