Tolerance to intensive exercise and high levels of lactate in panic disorder.

We wanted to test the tolerance of intensive exercise and corresponding high levels of lactate in patients with panic disorder. Thirty-five consecutive patients with DSM-III-R panic disorder completed submaximal tests, and 24 completed additional supramaximal exercise tests. All experienced high values of lactate during the supramaximal test (M = 10.7 mmol/L, SD = 2.9), but only 1 patient experienced a panic attack. The blood lactate values in the present study were higher than the usually achieved values of 5 to 6 mmol/L during infusion. In general, 67% of patients panic during infusion, compared to 4% in the present study. This discrepancy in frequency of panic following exposure to endogenous and exogenous lactate is discussed on the basis of various hypotheses of panic disorder, with an emphasis on cognitive theory of panic. The study indicates that patients with panic disorder can safely undergo vigorous exercise of such intensity to result in significant lactate production, with the chances of panic being small.