Physiology Heart, Circulation, and Blood 12225457 In severe exercise, decrease in pH is due to: A Respiratory acidosis B Lactic acidosis C H+ retention D HCO3 excretion High-Yield Explanation Ans. (b) Lactic acidosis(Ref: Guyton, 13th ed/p.1085)Accumulation of lactic acid causes decrease in pH, muscle cramps and muscle fatigue,