Misinterpretation of the Borg’s Rating of Perceived Exertion Scale by patients with panic disorder during ergospirometry challenge

INTRODUCTION: The most widely used instrument to measure perceived exertion or exercise intensity is the Borg’s Rating of Perceived Exertion (RPE) Scale. Panic attacks are aversive experiences that may be triggered by bodily sensations such as palpitations, breathlessness or dizziness due to increasing autonomic distress, prior sensitisation to panic and fear conditioning. The consequence is catastrophic interpretation of bodily sensations of arousal in general, which can lead to misinterpretation of exertion or exercise intensity. PURPOSE: To verify the effectiveness of the Borg’s RPE Scale as a measure of perceived effort in panic disorder subjects. METHODS: The study enrolled 72 subjects: the control group (C, healthy sedentary subjects, n=30) and patients with panic disorder (PD, n=42). All subjects were submitted to an ergospirometry challenge. Perceived exertion RPE scores and heart rate at 90% VO2max were compared between groups. RESULTS: Patients with PD showed lower levels of maximal oxygen consumption, when compared with C group [VO(2)max (mL/kg/min): PD=29.42±6.50xC=34.51±5.35; Student's t-test=−3.51; p <0.05]. Furthermore, among PD subjects, the maximum heart rate during ergospirometry challenge was lower than expected [predict max HR (bpm)=200.85±6.33xheart rate test (bpm)=178.86±7.28; Z=−5.64; p<0.05]. Perceived exertion, as measured by RPE, was also overestimated in relation to heart rate at 90% of maximum oxygen consumption compared with controls (RPE90%VO(2)max: PD=18.93±0.55xC=16.67±0.60; U=8.00; Z=7.42; p<0.05). CONCLUSIONS: The present study findings suggest that the Borg’s RPE Scale may not be an appropriate measure of subjective exertion among subjects with panic disorder performing a cardiopulmonary exercise test.