The exercise-induced hyperventilation during vigorous exercise is produced due to the receptors present in carotid bodies. When exercise becomes more vigourous,, buffering of the increased amounts of lactic acid that are produced liberates more CO2, and fuher increases ventilation. The additional increase in ventilation produced by the acidosis depends on the carotid bodies and doesnot occur if they are removed. Ref: Ganong&;s review of Medical Physiology 26th edition PGno: 646