Increased longevity is a social success that also implicitly entails enormous challenges: adding years to life often implies the management of more geriatric syndromes and higher mortality and disability rates. Although disease and disability are not inevitable consequences of human ageing, the risk of being affected by them considerably increases with age (Baltes & Smith, 2003). The concept of frailty is becoming increasingly relevant in the field of geriatric care, although its precise definition remains disputed (Clegg, Young, Iliffe, Rikkert, & Rockwood, 2013). Ageing is associated with a functional decline; however, its morbidity varies: the decline is faster and leads to increased morbidity and mortality in some individuals, yet others remain robust despite their advanced age. Clinicians and researchers use the notion of frailty to help them understand the heterogeneous nature of human ageing (Zaslavsky, Thompson, & Demiris, 2012) and the literature describes three main theoretical models to explain it. Rockwood and Mitnitski (2011) consider it to be a variable state of health resulting from the accumulation of deficits, Fried et al. (2001) understand it as an interrelated biological syndrome but differentiate it from disease and disability, and Gobbens, Van Assen, Luijkx, and Schols (2012) take a comprehensive view of frailty. The proposal by Fried et al. (2001) has received a broad consensus, is widely used in clinics and in research (Morley et al., 2013; Santos-Eggimann, Cuénoud, Spagnoli, & Junod, 2009), and represents considerable progress in the understanding and exploration the pathophysiology of frailty. They define frailty as a biological syndrome characterized by a decline in reserves and resistance to stressors resulting from an accumulation of deficits in multiple physiological systems, which causes vulnerability and adverse effects on health. The five frailty criteria that they proposed, the "frailty phenotype" (unintentional weight loss, muscular weakness, low energy, slow ambulation speed, and low physical activity) were extensively tested in the Cardiovascular Health Study (CHS). Those with none of the above components were considered as robust, whereas those with one or two components were considered as pre-frail and those with more than two components as frail. The CHS results showed that there was a greater tendency toward frailty in women, as well as an association between frailty and poorer health results: mortality, disability, and hospitalization. Numerous studies later used the same criteria and produced similar results (