Go to the Dr and get checked for Exercise Induced Asthma.

Hyperventilation was the trigger for me to do that. First it started with coughing a lot after hard efforts, and coughing a lot after cooler rides, and I suspected something was wrong. Then it moved into hyperventilation, and I went to the Dr, was diagnosed EIA, and got ventilators.

Until your Dr appointment, however, when you start to hyperventilate, slow down or stop and focus on exhaling. Exhale hard through your mouth.