The Association Between Cardiorespiratory Fitness Directly Assessed by the Cardiopulmonary Stress Test and the...

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 (VO_2max) 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: VO_2max 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.