Jason Day collapsed on his final hole during the second round of the U.S. Open after suffering from vertigo, which cause dizziness, lightheadedness, and unsteadiness. The Australian eventually got to his feet, finished the final hole and is 2-under-par for the tournament, three-strokes behind the leaders. His agent said Day was treated for vertigo and his wife said he will play the third round. Dr. Jordan S. Josephson offers his thoughts on what happened to Day and how vertigo impacts athletes.