The effort hypothesis at the heart of the virtuous circle

This article updates the “virtuous circle” model, which links physical exercise with cognition. This model, which originally focused on connectivity between the salience network (SN) and central executive network (CEN), now also incorporates the default mode network (DMN). It describes a bidirectional dynamic: exercise enhances executive functions (i.e., inhibition, flexibility, updating, planning, and problem-solving), which in turn strengthen long-term exercise adherence. This virtuous circle leads to cognitive, physiological, and motivational benefits through synergistic mechanisms induced by exercise such as the effort hypothesis (effort as an investment), the neurotrophic hypothesis, the cardiovascular hypothesis, the inflammatory hypothesis and the glucocorticoid hypothesis. These mechanisms improve connectivity within large-scale neuronal networks, thereby consolidating behavioral regulation. Compared with other behavior change models (e.g., regulation, dual-process, stage-based, and integrative models), the virtuous circle model is notable in light of its circular nature and emphasis on sustainability. In this theoretical framework, adherence to exercise is defined as an evolving strength of the attitude–behavior link, which is shaped by three interconnected processes: immediate motivation (pleasure, mood improvement, social interaction, and rewards), which initiates engagement; sustained effort, which enhances executive control, reduces perceived costs, and fosters habit formation; and behavior-driven attitude change, through cognitive dissonance and effort justification, which aligns beliefs with actions. Recent longitudinal studies have supported the reciprocal associations among exercise, cognition, and brain health, although further trials are needed. This model highlights the fact that early adoption of the virtuous circle promotes the development of health-protective habits, thereby slowing both physical and cognitive aging. In contrast, sedentary lifestyles foster a vicious circle that accelerates decline.