Prefrontal Cortex Neurovascular Coupling Mediates The Relationship Between Fat Mass And Exercise Tolerance In Overweight/Obese Individuals

Physical inactivity and fat mass are linked to exercise (in)tolerance, however, it is unclear how cognitive control and the prefrontal cortex (PFC) can modulate bodily sensations and tolerate highly demanding exercise. PURPOSE: To examine the role of the PFC's neurovascular coupling (PFC-NVC) in the relationship between body fat and exercise tolerance. Also, we explored the PFC efficiency in converting oxygenation in perceived exertion and discomfort levels during exercise. METHODS: Thirty-two physically inactive young adults (age: 28.3 ± 4.9, 16 men and 16 women) partook in assessments of body fat (iDXA), interoceptive awareness (Multidimensional Assessment of Interoceptive Awareness), cognitive inhibitory control (Stroop test), and maximal incremental (VO2max) and tolerance cycling performance (constant-load test performed at the ventilatory threshold). PFC hemodynamics (fNIRS) was monitored during the cognitive inhibitory control and exercise tolerance test. RESULTS: Higher body fat correlated with lower exercise tolerance, and this relationship was mediated by PFC-NVC (ps < 0.05). Also, individuals with greater PFC-NVC exhibited higher efficiency in integrating cerebral oxygenation with heightened ratings of perceived exertion (ß = 0.77, p < 0.05) and a higher efficiency in regulating displeasure (ß = -0.31, p < 0.05; i.e., lower costs of oxygenation relative to affect) during the final stage of the exercise tolerance test. Furthermore, they also had a higher interoceptive profile marked by low distraction (ß = -0.45, p = 0.006) and increased self-regulation (ß = 0.39, p = 0.04). CONCLUSION: Our findings suggest that the link between accumulated body fat and exercise intolerance may be explained by a lower ability of the PFC to convert hemodynamic responses into favorable cognitive control to interpret and tolerate exercising demands in physically inactive adults.