Objective: To investigate whether physical fitness is decreased in patients with major depressive disorder (MDD) in comparison to matched healthy controls because low physical fitness has been shown to be associated with metabolic syndrome or autonomic dysfunction. Cardiovascular morbidity and mortality are known to be increased in patients with MDD. Furthermore, the effect of a single exhaustive exercise task on heart rate recovery (HRR) and mood was examined.
Methods: Peak oxygen consumption (VO(2)peak), maximum workload (P peak), and individual anaerobic threshold (IAT) were assessed in 22 patients suffering from MDD and 22 controls in a stepwise exhaustion protocol, using spirometry and lactate diagnostics. HRR was detected within the first minute after recovery. The Self-Assessment Manikin (SAM) was used to assess mood before and after exercise.
Results: VO(2)peak, P peak, and IAT were decreased significantly in patients, indicating reduced physical fitness in MDD as compared with control subjects. A single exercise exhaustion significantly improved mood in patients, but not in controls. Mood improvement in patients correlated with maximum lactate levels. Significantly reduced HRR values in patients further point to an elevated cardiovascular risk profile and autonomic dysfunction.
Conclusions: Our results indicate reduced physical fitness in patients with MDD. Thus, special training programs should be developed to improve their cardiovascular risk profile. In addition, the intriguing finding of a correlation between lactate levels and mood changes should be followed up in future studies to unravel putative mechanisms.