Examining changes in dynamic balance in older adults after balance training with attentional focus cues

Functional balance in humans can be characterized as maintaining the center of mass (COM) within the base of support (BOS). When the COM moves outside the BOS, a fall can occur if there is not an immediate reaction to modify the BOS. The ability to dynamically control the COM-BOS interaction declines with age, and this increases fall rates in older adults. Falls are multifactorial, and there are some common deficits connected to a change in motor control, as evidenced by greater variability in balance performance. Less variability in motor performance is indicative of a more functional and healthier neuromotor system. There is a gap in the literature with respect to the ability to objectively measure dynamic balance and how it relates to fall-risk. Clinical and perceptual assessments of balance are commonly employed; however, they rely on subjective judgements. Objective assessments have become more available in recent years through sensors in smartphone apps, including the AccWalker app that was developed in our laboratory. Yet, it has been unknown the extent to which these objective measures differ between groups based on age and fall status. This gap was important to address so that smartphone apps can be deployed to the clinical community in order to provide objective, evidence-based assessments of dynamic balance. Treating balance changes had been challenging, despite the designation of falls as a public health concern. Previously, less complete strategies have included strengthening exercises, T’ai Chi, physical therapy and the use of walking assistive devices. A newer strategy with success in the literature is the use of attentional focus cues, particularly external focus instruction. The addition of dynamic balance training with internal (IF) and external focus (EF) cues allows for the examination of the role of attentional focus on fall risk in older adults. This dissertation addressed these gaps in the literature via three specific aims. Manuscript 1 investigated whether older and younger adults were similar in the phone app task for timing of steps in response to the app cue, as well as peak flexion of the right hip. The older adults and younger adults were not different in any variable, but trends were noted with lower variability and greater excursion of thigh flexion for the younger adults and older adults who had not fallen. Manuscript 2 explored the results of the three groups of older adults who were trained with attentional focus cues or were part of the control group. The group that received IF training cues were unchanged for all seven variables of the AccWalker phone app over the twenty-week intervention. In addition, the headshake (HS) condition was unchanged for all seven AccWalker variables over the twenty-week intervention for all three groups. SD stride time, SD peak flexion, and COV peak flexion (variability) increased during training for both eyes open (EO) and eyes closed (EC) conditions, but dropped in the retention phase for EF condition only. Thigh ROM decreased for both control and EF in training but increased for EF only in retention. These results imply a delayed response with EF training, but no effect for IF training. Manuscript 3 investigated the correlation of the variables of standardized tests with the phone variables, and found the Timed Up and Go, Functional Gait Assessment, ABC Scale and Berg Balance Scale were correlated to Thigh ROM and Mean Peak Flexion with all conditions (EO, EC, HS), as well as with step timing variability for FGA and Berg in headshake and eyes closed condition. Grip strength only correlated with the training time frame of the study, but not with balance testing. Grip may be uncorrelated if changes of aging in the upper extremity have disparity to the changes of lower extremities