Enhancing Physical Reserve to Promote Resilience in Physically Frail Older Adults

Objectives: (1) To compared with usual care (i.e., CON), will 3-month aerobic and resistance training (ATRT) improve physical reserve in older adults with physical frailty? (2) Compared with CON, will ATRT lead to changes in the neural network organization? (3) Will improved physical reserve lead to better maintenance of cognitive and physical functioning in spite of presence of white matter hyperintensities (WMH)? (4) What is the association between exercise, neural network, and physical reserve? Hypotheses: Investigator hypothesize that (1) compared to participants randomly assigned to the CON, participants randomly assigned to the 3-month ATRT will show significantly enhanced physical reserve. (2) compared with participants randomly assigned to CON, participants randomly assigned to ATRT will show reduction in Dorsal Attention Network connectivity. (3) Enhanced physical reserve will moderate the negative association between WMH and Trail Making Test performance, as well as WMH and Short Physical Performance Battery performance. (4) combined aerobic and resistance training will enhance physical reserve via a mediated relationship with reduced Dorsal Attention Network connectivity.

Design and subjects: A randomized controlled trial involving 224 community-dwelling older adults with physical frailty Study instruments: Magnetic resonance imaging Interventions: The designed exercise training will be progressive and moderate in intensity. Participants randomized to the ATRT group will undergo a 3-month (i.e., 13-weeks) four-sessions-per-week, 60-minute-per-session exercise with a 10-minute warm-up, 40-minute of moderate intensity exercise training, and 10-minute cool-down. There will be a total of 52 exercise sessions with a 1:3 research staffs (i.e., instructor and assistants) to study participants ratio. To promote participant safety, investigator will limit each session to 12 study participants. To ensure fidelity of the intervention across time, a detailed manual of procedures for each experimental group will be developed and used for staff training.

Data analysis: All analyses will follow the intent to treat principle. The principle investigator will lead all analyses with support from collaborators on WMH quantification and structural MRI analyses. The intention-to-treat analysis will be conducted with multiple imputation followed by a complete-case analysis. Statistical significance for all analyses will be defined at α < 0.05.

Inclusion criteria

• are community-dwelling (i.e., not residing in a nursing home or extended care unit) ;
• scored < 9/12 on the SPPB;
• scored >18/30 on the MoCA;
• are able to walk independently; use of walking aid is acceptable;
• are able to safely engage in exercise as indicated by the Physical Activity Readiness Questionnaire Plus33 and confirmed by their physician;
• have internet at home; and
• are able to provide written informed consent.

Exclusion criteria

• diagnosed with dementia or stroke;
• self-report engaging in strength and balance training exercises > two-times-per-week in the 3 months prior to screening;
• unable to understand, speak, and read Cantonese/Chinese/English proficiently; and
• contraindications for MRI such as MRI-incompatible implants.