Ventilatory inefficiency in major depressive disorder: a potential adjunct for cardiac risk stratification in depressive disorders?

BACKGROUND: Cardiopulmonary exercise testing (CPET) provides insights into ventilatory, cardiac and metabolic dysfunction in heart and lung diseases and might play a role in cardiac risk stratification in major depressive disorder (MDD). OBJECTIVE: The VE/VCO(2)-slope indicates ventilatory efficiency and has been applied to stratify the cardiac risk in heart failure (HF). Therefore, the current study was conducted to evaluate and classify ventilatory efficiency and its relationship to physical fitness and disease severity in MDD. METHODS: Exhaustive incremental exercise testing was completed by 15 female MDD patients and pair matched controls. The ventilatory threshold (VT) and the VE/VCO(2)-slope were assessed. Statistical analyses were conducted by means of MANOVAs and follow-up univariate ANOVAs. RESULTS: In patients with MDD, significant different relative work rates and oxygen uptakes at the VT in comparison to healthy controls were observed. Furthermore, we found an increased VE/VCO(2)-slope in depressed patients. We additionally report an inverse relationship between the VE/VCO(2)-slope and peak power output as well as peak oxygen uptake solely in patients. We did not observe any association of assessed parameters with disease severity. CONCLUSION: CPET measures indicate ventilatory inefficiency in patients with MDD. The elevated VE/VCO(2)-slope indicates that patients with MDD need to ventilate significantly more to a given amount of developing CO(2). Further investigations are needed to verify the application of the ventilatory classification system to stratify cardiovascular risk in depressive disorder.

Dissociation of performance parameters at the IAT requires specific exercise recommendations for depressed patients.

Aerobic exercise training is considered an adequate complementary treatment strategy for major depressive disorder (MDD). However, there is a need for comparative methodological investigations to determine the appropriate exercise intensity for these patients. The study compared submaximal exercise intensity determination with those derived from maximal parameters such as percentages of heart rate reserve (HRR), maximal heart rate (HR(max)) and peak oxygen uptake (VO(2peak)) of patients and controls. An exhaustive incremental bicycle exercise test was completed by 15 female MDD patients and matched controls. The individual anaerobic lactate threshold (IAT) as a gold standard to determine individual aerobic exercise intensity was assessed according to Stegmann and coworkers. Exercise intensities at 70 and 85% of HR(max), 70 and 85% of HRR and 50 to 80% of VO(2peak) were compared to the IAT. Patients suffering from MDD switched earlier to anaerobic metabolism than matched healthy controls. But interestingly, the level of self-rated perceived exertion, concentration of lactate, respiratory exchange ratio and heart rate at the IAT level revealed no significant difference between both groups. Due to a growing number of clinical aerobic exercise treatments in depressive disorders exercise intensities >70% of (a) HR(max), (b) HRR, (c) VO(2peak) should be amended by the IAT and Borg scale measurements to avoid over challenging as well as increased anaerobic metabolism.