Background/Objective: Frailty is linked to poor health outcomes in adults. However, less is known about the lifestyle factors, specifically physical exercise or sedentary behaviour that lead to the development of frailty. The objective is of this systematic review is to determine the impact of the relationship that physical exercise or sedentary behaviour has on the development of frailty in adults.

Methods: MEDLINE, EMBASE, Ageline, Sport Discus, and CINAHL will be searched for the earliest possible studies in adults ≥18 years old who are free from frailty at the beginning of the studies. Eligible studies must include a formal assessment of frailty, either by self-report, single or multiple performance measures, or combined procedures; they must use a multivariable that include the measurement of physical exercise or the self-reporting of fitness behaviour and the development of frailty; and they must have a minimum one-year follow up. Studies not written in English will be excluded. Two reviewers will independently screen the titles and abstracts of potential studies, and the full-text review for final inclusion in the systematic review. Disagreements for article inclusion will be resolved by a third reviewer. Data extraction will be completed by two independent reviewers, which will include study characteristics (e.g., authors, year, sample size, study population of interest), participant characteristics (e.g., demographics and clinical features), statistical methods used, and physical exercise and/or sedentary behaviour assessed. A meta-analysis will be completed if >1 studies assesses physical exercise or sedentary behavior. The model adjusting for the most covariates in each individual study will be used for meta-analysis. Statistical heterogeneity will be assessed using the I2 test. A fixed-effects or random-effects model for meta-analysis will be performed depending on statistical heterogeneity. Risk of bias of individual studies will be completed using the Newcastle-Ottawa Scale. Results and Conclusion: To be determined.