Association of Klotho with physical performance and frailty in middle-aged and older adults: A systematic review.

Ageing is an inevitable process of physical deterioration that impairs functional autonomy and quality of life, becoming a public health issue. Since the percentage of people over 60 years is increasing worldwide, the use of easily detectable biomarkers of ageing is a relevant tool for monitoring of the ageing process and treatment. Among them, Klotho, an ageing suppressor gene because its deficiency leads to ageing like phenotype, seems particularly promising. This systematic review includes the last 10 years clinical studies that evaluated the association between plasma Klotho and body composition, physical performance and frailty in both sedentary and active middle-aged and older adults. Sixteen studies have been found: nine regarding the association between Klotho and body composition, two the association of Klotho and frailty and finally five concerning the effects of physical activity on Klotho. The results of these studies, albeit with some exceptions, point out that Klotho is positively associated with muscle strength and negatively with osteoporosis, frailty, disability and mortality while physical activity generally increases Klotho levels. Moreover, even if there are still few clinical studies, Klotho might be positively associated with bone mineral density, muscle strength, longevity, mobility and robustness during ageing.