Overview: This study comprises three Specific Aims (SAs): SA-1) Development of the Balanced Assessment and Training Protocol (BATP). SA-2) Assessment of the BATP's training efficacy. SA-3) Assessment of the BATP's time course of motor learning.
Methods Related to Specific Aim 1: Development of the BATP SA-1.1: Develop of the BATP's Assessment Module. The investigators will develop a BATP such that each foot's position and its associated vertical ground reaction force (used to detect stepping), as measured by the investigators' extant measurement systems, are continuously streamed to a Real Time Computing Workstation and read by the experimental control program, enabling it to monitor these quantities on an ongoing basis. The investigators will next incorporate code to establish target disk position corresponding to the subject's Limit of Balance (LoB), based on stepping. The investigators will establish LoB corresponding to seven target disk motion directions, each corresponding to a particular direction of Center of Mass (CoM) Motion. Target motion will be programmed to move unpredictably within a small circular region with center r and centerline coinciding with one of the specified directional lines. The subject then tracks the target using their dominant hand index finger until the subject (wearing a harness to guard against falling) must step to avoid a loss of balance. During this task the subject will be instructed to step rather than curtail their tracking movements when they believe they are at risk of falling. LoB in each direction is the point at which the subject steps.
The Assessment Module will record the following data to characterize performance in the tracking task
1. The values of r, , and LoB corresponding to each (Figs. 7A and 1);
2. The motion (position vs. time) of the target disk;
3. The motion of each of 15 body segments (Table 1), and the tip of the tracking finger (measured by the investigators' Vicon Motion Capture System);
4. Ground reaction forces, moments, and CoP for each foot and for both feet combined (dual Bertec force plates); All data will be saved for offline post-test processing and analyses. SA-1.2: Develop the BATP's Training Module. A single training session begins by administering the Assessment Module to establish the subject's LoB and corresponding overall target excursion amplitude, and computing the unpredictable target disk trajectory based upon it. The Training Module then presents an operator-specified number of training bouts; a single one of which consists of presenting the trajectory for the subject to track for four minutes without stepping, followed by a three minute sitting rest period. Performance data is recorded throughout the tracking period. Training bout and rest period durations can be varied (with the goal that a training session deliver 60 minutes of actual training) to optimize training efficacy and accommodate individual subject needs and capabilities. Subjects will be harnessed while performing the tracking task to guard against falling. As training progresses and the subject's performance improves, the BATP will present increasingly difficult target trajectories based upon the increased LoBs and corresponding overall target excursion amplitudes as measured by the Assessment Module at the beginning of each training session.
Methods Related to Specific Aim 2: Assessment of the BATP's training efficacy SA-2.1: Conduct the BATP and MMBI training protocols. All subject testing is performed in this Specific Aim. The investigators will screen 90 older men and women with high fall risk, enrolling 80 of these, and completing training for 68, assuming an overall 25% attrition rate.
Subjects will be randomly assigned to either the BATP or MMBI training group. Each group will receive 60 minutes of training three times per week for six weeks. BATP training is as described previously (see SA-1.2). The VA Maryland team developed an MMBI protocol for older individuals with balance and mobility disability. The program is individualized to each participant's capacity based on their balance profile and endurance level. Across the six weeks, training advances from five "fundamental" exercises that are essential for instrumental activities of daily living function to 13 exercises, as participants meet metrics for exercise safety and movement quality. Standardized progressions for each exercise advance according to the level of hand contact support required, dose (duration, sets and repetitions), intensity (movement amplitude and cadence), and multi-segmental motor challenge or complexity. The exercise cadence is adjusted up to provide greater challenge to aerobic fitness and is adjusted down to facilitate greater resistive training benefit (i.e. holding a squat longer) or to accommodate the participant's fatigue level. MMBI training will be performed in a group setting.
All subjects will be assessed with the clinical balance measures (see below) and the BATP Assessment Module at the same time points before, during, and after training (see SA-2.2).
Outcome Measures: The following "clinical measures" of balance, reach, and fall risk will be used to asses training effects induced by the BATP and MMBI.
1.Multi-Directional Reach Test 2.Falls Efficacy Scale, which assesses FoF 3.Physiological Profile Assessment (PPA) 4.Tinetti Balance Test (Balance Section) 5.Mini Balance Evaluation Systems Test (Mini-BESTest) 7.Falls experienced by each subject, as well as the conditions in which they fell, during and throughout the first year following training.
These measures will be obtained on a separate day from the BATP Assessment and Training procedures so as not to unduly fatigue the test subjects. The investigators will also employ the following BATP-based measures of balance and reach.
8.RMSE 9.RMSD-Primary Outcome Measure 10.Average SoB 11.LoB RMSD will be the investigators' primary outcome measure.
SA-2.2: Assess the training efficacy of BATP training in comparison to MMBI. Prior to training subjects will undergo double baseline tests 48 hours apart using the clinical measures and the BATP-related measures. This assessment will be repeated midway through training (three weeks after training begins), immediately post training, and six-weeks after the last training session (retention). Although the investigators include a number of clinical and BATP-related performance measures in the assessment of training efficacy, RMSD will be the investigators' primary outcome measure. The primary purpose of this study is to assess the efficacy of the BATP in improving balance. It is possible that while both the BATP and MMBI improve balance the magnitude of the difference in improvement between groups may be small. As a consequence of the relatively modest number of subjects the investigators will be testing (a result of the demands of the testing and the limited funds available to support the testing) the investigators may show no between-group difference. In order to be able to demonstrate that each intervention is efficacious, the investigators will test subjects twice at baseline and compare the change during this non-intervention period separately to the change engendered by each active intervention. The investigators' balance-related clinical measures have been shown to correlate with fall risk and fear of falling (FoF). Clinically meaningful improvements in the training group's performance based on the clinical measures will indicate that the BATP improves balance function and reduces fall risk.
The investigators will also request that subjects report any falls that they experience during the training period, and the conditions under which they fell. Once subjects have completed training the investigators will contact them monthly via e-mail, social media, or using stamped return-address post cards to obtain fall information; and follow by telephone to learn of the conditions under which they fell.
