AquaReBal - Aquatic Reactive Balance Training for Older Adults

Feasibility of recruitment, adherence and intervention fidelity will be measured. Because feasibility is a multidimensional construct we will also collect qualitative data about recruitment capability, randomization acceptability, data collection procedures and outcome measures, intervention delivery, intervention adherence and safety, barriers and facilitators to implementing the study, and retention of participants. Qualitative methods will include one-on-one interviews, unstructured observations, field notes and session recordings. We will use a flexible approach with regard to timing when qualitative data is collected as problems and implementation barriers arise; this will allow us to document information in real time, thus allowing us to make necessary refinements to the intervention and study protocol.

The number of falls experienced by the participants will be monitored. Within 24 hours of experiencing a fall, the participants will complete a fall survey, either online or on paper. The survey will be composed of multiple-choice questions with closed-ended answers concerning the location of the fall and time of the day, as well as multiple-choice questions with an open-ended "other" option regarding the activity being performed at the time of the fall and potential contributing variables. In addition the survey will include questions about possible injuries from falling. A researcher will conduct monthly interviews with participants by phone or MS Teams to ensure the fall surveys are completed.

The Mini Balance Evaluation Systems Test (mini-BESTest) is a 14-item observational rating scale that assesses systems underlying balance control, including reactive balance control and dynamic stability during walking. The Mini-BESTest is reliable and valid, and able to identify fall status in older people living in the community.

Timed Up and Go (TUG) is a commonly-used screening tool for fall risk in the inpatient and community setting. A faster time indicates better functional performance and a score of ≥13.5 s is used as a cut-point to identify those at increased risk of falls. The TUG test has shown acceptable psychometric properties and is considered appropriate for the general older adult population.

The Physical Activity Scale for the Elderly (PASE) is a 12-item reliable and valid self-report instrument specifically designed for older adults. It is used to assess physical activity over a one-week time period.

The Activities-Specific Balance Confidence scale (ABC scale) is a self-report measure where participants rate their confidence in performing daily tasks while standing and walking using percentages, with higher percentages indicating more confidence. The ABC scale demonstrated strong internal consistency reliability in community-dwelling older adults.

5-level EuroQoL is simple measure of health-related quality of life and has been used widely in older adults.

To assess reactive balance control, participants will be outfitted with reflective markers and complete 8-10 walking trials on a movable platform. In two trials, the platform will move forward suddenly on heel strike to trigger a slip-like perturbation. In two other trials, the platform will move backward suddenly on toe-off to trigger a trip-like perturbation. The perturbation waveform will consist of a 300 ms square-wave acceleration, followed immediately by 300 ms deceleration. The remaining four to six trials will consist of unperturbed walking. The slip/trip and unperturbed walking trials will be presented in pseudorandom order. Reactive balance will be measured using three-dimensional motion capture (Vicon Motion Systems, Oxford, UK), and force plates (AMTI, Watertown, MA, USA). When responding to the perturbation, biomechanical stability will be measured using an established method that considers the distance between the center of mass and base of support.