Xuxi Zhang

DISCUSSION Our study aimed to examine the longitudinal association between the frequency of moderate PA and frailty among community ‐ dwelling older adults older than 70 years. We found that participants who undertook moderate PA with a regular frequency at baseline were less overall frail at follow ‐ up than participants with a low frequency. Second, we assessed the association between a 12 ‐ month change in frequency of moderate PA and frailty. Older adults who undertook moderate PA with an increased frequency were less overall frail at follow ‐ up than they were at baseline. Older adults who undertook moderate PA with a continued regular frequency were least overall frail at baseline and at 12 ‐ month follow ‐ up. Interestingly, after controlling all the covariates and baseline overall frailty, the follow ‐ up overall frailty levels of participants who undertook moderate PA with an increased frequency were similar to those with a continued regular frequency. These findings indicate that maintaining a regular frequency of PA as well as increasing frequency of PA are associated with maintaining or improving overall frailty (multidimensional). Previous observational studies 3, 10, 15 also found that PA is associated with a delay in progression of frailty among older adults, but these studies focused on physical frailty. More studies on multidimensional frailty are still needed. Additionally, some randomized controlled trials (RCTs) on the effect of PA intervention on physical frailty showed conflicting results. An RCT among 424 older adults found that regular PA could reduce the presence and severity of physical frailty, especially in individuals at higher risk of disability. 9 In contrast, a secondary analysis of an RCT among 1635 older adults reported that a structured, moderate ‐ intensity PA program was not associated with a reduction in the overall risk of physical frailty. 12 These differing results may be due to the different characteristics of PA intervention methods (e.g. the intensity, frequency and duration of PA) as well as differing frailty criteria among studies. 7, 12 RCTs that study the effect of various kinds of PA intervention (e.g. moderate or vigorous activity or a combination of both with different frequency and duration) on frailty are needed to determine the optimal level of PA among older adults. In addition to overall and physical frailty, our findings report on the longitudinal association between PA and psychological and social frailty. After controlling all the covariates and baseline frailty, we found that older adults who undertook moderate PA with a continued regular frequency were least psychologically and socially frail at baseline and follow ‐ up, and that the follow ‐ up psychological and social frailty levels of participants who undertook moderate PA with an increased frequency were similar to those with a continued regular frequency. Regarding psychological frailty, a controlled study of older adults aged 61 to 89 years in Canada found that PA training could improve cognitive functioning and psychological well ‐ being. 27 A systematic review of 11 RCTs to assess the effect of PA on depression found that PA may reduce depression or depressive symptoms in adults older than 60 years. 28 A qualitative study among older adults aged 80 to 91 years in Sweden reported that PA could help older adults to have the energy to be active and to improve their mood, because PA was 62 Chapter 3