The association between cardiorespiratory fitness directly assessed by the cardiopulmonary stress test and the perception of stress

Background/Objectives: Cardiorespiratory fitness (CRF) represents a strong and consistent predictor of mortality among adults. It is ideally expressed as the maximum or peak rate of oxygen consumption per kilogram of body mass (VO2max) determined by the cardiopulmonary exercise test (CPX). Variance in CRF is mainly attributable to genetics and physical training; nevertheless, strong behavioral and socioeconomic confounders need to be considered. Among those, psychosocial stress may play an important role. Some papers show an association between low CRF and chronic stress conditions; nevertheless, CRF is generally estimated by indirect assessment and not directly measured by CPX. Methods: CRF was directly assessed by performing a CPX in 145 consecutive subjects (56 male, 89 female) (age 19–65 years) who attended our Exercise Medicine unit for health check-ups. Weekly total volume of physical activity (PA) was evaluated using a validated questionnaire (IPAQ); perceptions of stress, fatigue, and somatic symptoms were assessed using a self-administered questionnaire. Results: VO2max was negatively correlated with perception of stress (p = 0.03), fatigue (p < 0.001), and somatic symptoms (p < 0.001); as expected, it was positively correlated with the weekly volume of PA (p < 0.001). This link was further evidenced by the observation that subjects who did not meet the PA goals as indicated by WHO guidelines presented a higher perception of stress, fatigue, and symptoms, as compared to physically active subjects. Conclusions: This direct link might, on the one hand, corroborate the role of exercise as a tool to manage stress and, on the other hand, focus on the role of stress as a possible determinant of CRF.