What can we learn from physical capacity about biological age? A systematic review

Objective: To systematically investigate the relationship between objective measures of physical capacity (e.g., cardio-respiratory fitness or daily step count) and biological age, measured in different ways. Data source: PubMed; SCOPUS - Elsevier API; and Web of Science - ISI 1984-present, as well as contextual search engines used to identify additional relevant publications. Study selection: Cross-sectional and longitudinal studies that assessed the association between objectively measured physical capacity and biological aging in adult individuals (age>18). Results: Analysis of 28 studies demonstrated that physical capacity is positively associated with biological aging; the most dominant measures of physical capacity are muscular strength or gait speed. The majority of the studies estimated biological aging by a single methodology – either Leukocyte Telomere Length or DNA methylation levels. Conclusions: This systematic review of the objective physical capacity measures used to estimate aging finds that the current literature is limited insofar as it overlooks the potential contribution of many feasible markers. We recommend measuring physical capacity in the context of aging using a wide range of modifiable behavioral markers, beyond simple muscle strength or simple gait speed. Forming a feasible and diversified method for estimating physical capacity through which it will also be possible to estimate biological aging in wide population studies is essential for the development of interventions that may alleviate the burden of age-related disease.