Background: Frailty is an age-related condition that implies a vulnerability status affecting quality of life and independence of the elderly. Physical fitness is closely related to frailty, as some of its components are used for the detection of this condition.
Objectives: This systematic review and meta-analysis was conducted to investigate the magnitude of the associations between frailty and different physical fitness components and to analyse if several health-related factors can act as mediators in the relationship between physical fitness and frailty.
Methods: A systematic search was conducted of PubMed, SPORTDiscus, and Web of Science, covering the period from the respective start date of each database to March 2020, published in English, Spanish or Portuguese. Two investigators evaluated 1649 studies against the inclusion criteria (cohort and cross-sectional studies in humans aged ≥ 60 years that measured physical fitness with validated tests and frailty according to the Fried Frailty Phenotype or the Rockwood Frailty Index). The quality assessment tool for observational cross-sectional studies was used to assess the quality of the studies.
Results: Twenty studies including 13,527 participants met the inclusion criteria. A significant relationship was found between frailty and each physical fitness component. Usual walking speed was the physical fitness variable most strongly associated with frailty status, followed by aerobic capacity, maximum walking speed, lower body strength and grip strength. Potential mediators such as age, sex, body mass index or institutionalization status did not account for the heterogeneity between studies following a meta-regression.
Conclusions: Taken together, these findings suggest a clear association between physical fitness components and frailty syndrome in elderly people, with usual walking speed being the most strongly associated fitness test. These results may help to design useful strategies, to attenuate or prevent frailty in elders.
Systematic review registration: PROSPERO registration no. CRD42020149604 (date of registration: 03/12/2019).