What is the role played by physical activity and exercise in the frailty syndrome? Perspectives for future research.

Exercise and physical activity play an important role in physical frailty, but we do not know if they are markers, components and/or correlates of this syndrome. The purpose of this paper is briefly to discuss the potential roles played by physical activity and exercise on the development and progression of frailty, and to propose directions for future research in this field. Exercise practice lowers the levels of some frailty markers, such as tumor necrosis factor-alpha, interleukin-6, C-reactive protein, and uric acid, and also resistance to insulin. The influence of exercise on the main frailty domains is also well established in the literature. Exercise improves muscle strength, gait speed, cognition (particularly executive control related-tasks), weight maintenance, mood and, to a lesser extent, feelings of energy. Although exercise and physical activity positively influence the main frailty markers and domains, most findings were obtained for other elderly populations (e.g., healthy elderly, clinical populations). For future research, efforts must be made to define some key concepts (exercise or physical activity) in selecting study samples and in establishing intervention length. Attention must also be paid to identifying the most efficacious exercise interventions regarding type, frequency, intensity and session duration, and approaching a dose-response relationship between a physically active life-style and frailty. Thus, further research, especially longitudinal randomized controlled trials, is needed to understand the role of physical activity and exercise in the frailty syndrome.