Doctors, what is the difference between hyperventilation and heavy exercise?

CO2: Hyperventilation can be purposeful or the result of such things as anxiety or fear or panic. This is a rapid breathing situation in which the CO2 is quickly decreased and you are oversaturated with O2. This may result in dizziness, tingling/numbness, etc. Tachypnea and hyperpnea (rapid and fast/deep breathing) may result from heavy exercise in order to supply the body's demands for more O2.

The difference: Hyperventilation technically refers to excess oxygen in the lungs, without the capacity to transfer it to the blood. During heavy exercise, there is actually less oxygen available than is required. In this case the blood CO2 stays stable.