Effects of acute exercise on CO2‐induced fear

Background Acute exercise has shown to reduce the effects of experimental panic provocation in healthy volunteers and in patients with panic disorder. Recent evidence suggests that when larger amounts of CO2 are inhaled, a large proportion of healthy subjects can also develop an affective response consistent with definitions of a panic attack. Our aim was to test whether exercise can show antipanic effects in healthy subjects when exposed to higher concentrations of CO2. Methods Thirty-one healthy subjects, on four separate occasions in a randomized Latin square design, performed either moderate/hard or very-light exercise immediately followed by either a single or a double 35% CO2/65% O2 inhalation. Results Compared to very-light exercise, when subjects performed moderate/hard exercise they reported a reduction in panic symptoms on the Panic Symptom List and the Visual Analogue Scale of Fear but no difference on the Visual Analogue Scale of Discomfort after a double CO2 inhalation. After a single CO2 inhalation, reductions were only seen on the Panic Symptom List. Conclusions After intense exercise, subjects had less panic symptoms when exposed 35% CO2, particularly after a double inhalation. Depression and Anxiety 0:1–4, 2011.© 2011 Wiley-Liss, Inc.