<qa>  What is the pathophysiology of frailty?Though most physicians believe they can identify frail patients, frailty is a poorly characterized and complex clinical syndrome. Frailty has been categorized four dimensions by de Vries et al: 1 physical physical activity, nutrition, mobility, strength and energy; 2 biochemical nutritional and inflammatory biomarkers; 3 psychological cognition and mood; and, 4 social social contact and support. 1 However, the pathophysiology of frailty remains unclear. Two broad hypotheses have been proposed. 