Six sessions of the class were offered during the time period of this pilot study, and each session was filled to maximum capacity of 15 participants. Interest has been strong enough among the center clients and from outside sources that the center has continued to offer the original class upon completion of the grant funding period. Other Senior Centers in the area are also interested in offering the class.
Of the 76 individuals who initially enrolled in the study, 52 were posttested at 12 weeks. Reasons for not completing the 12-week posttesting include: scheduling conflicts with the posttest (5), moved (2), became ill (5), unrelated knee pain (2), did not show up on posttest date and could not be rescheduled (2), and dropped the class for no specific reason or could not be contacted (8).
A comparison of those who participated in posttesting versus those who did not revealed significant differences in the ability to perform the timed chair rise (TCR), the timed 360, and the FSST. However, no differences between groups were found in Timed Up and Go, gait speed, tandem stance or single leg stance, or any of the cognitive tests. The greatest differences between these groups were in the amount of time required to complete the FSST and TCR tasks (Table 1).
Exploration of the data suggested that not all individuals experienced the same improvements in measures. A secondary analysis was performed to determine if baseline walking speed influenced outcome measures. Average walking speeds of 1.0 m/s or less are associated with increased risk of falls,54 frailty,55 and increased risk of morbidity and mortality.40,56 For our purposes, individuals who walked at 1.0 m/s or faster at baseline were categorized as Fast (n = 24), and all others categorized as Slow (n = 21). Results from the 2-way mixed model repeated measures ANOVA indicated a significant within subject main effect for time on the physical performance outcomes of tandem stance, TCR, timed 360, and FSST, but no significant interaction between time and group. There were also significant main effects for differences between groups in the performance of the TUG, TCR, 360 and FSST (P < .01). For the cognitive measures, there was a significant within subject effect of time for the SDMT and Trails A (P < .05) and a significant interaction between time and group for outcome measures of Trails A and Trails B (P < .05). The mean, standard deviation, and range were then calculated for the baseline and posttest measures to identify where the groups differed in improvements in performance measures (Table 3).
The preliminary findings of this study suggest that participation in a 12 week exercise-based balance improvement program can have a positive effect on cognitive as well as physical performance. The improved performance of executive function and processing speed demonstrated by older adults after participating in a community-based group exercise programs is a novel finding. These preliminary results lend support to the hypothesis that exercise-based falls prevention interventions may have a positive association with cognitive performance. This association could be one of the mechanisms contributing to improved balance and, potentially, to decreasing falls risk.5 Liu-Ambrose studied cognitive performance of 74 older adults (mean age 81 years) participating in the Otago Exercise Program at baseline and after 6 months. This home-based program consisted of three 30 minute sessions of strength training and 2-walking sessions per week.57 Participants in the intervention group demonstrated significant improvements in response inhibition,5 which is the ability to inhibit irrelevant information.58 A striking finding of the Otago exercise study was that the intervention group did not show significant reductions in physiologic falls risk or in functional mobility, but did demonstrate a 47% reduction in falls rates compared to controls.5 Other exercise-based interventions have reported similar findings of decreased rates of falls after the intervention period without a concurrent improvement in physical performance.4,59 Liu-Ambrose was the first to suggest that cognitive performance may be the missing link explaining this outcome.5
Our participants demonstrated significant improvements in the SDMT and a trend toward significant differences in the Trails A. The SDMT is a measure of processing speed which plays a role not only in maintaining one's balance but in age-related cognitive decline.21 The Trails A is a measure of visual search, scanning, speed of processing, and mental flexibility.49 Participants in the Liu-Ambrose study were tested on cognitive processes of set-shifting, updating, and response inhibition with significant improvements only in response-inhibition. Participants in our study demonstrated improvements in processing speed and mental flexibility, which may be related to the difference in the interventions. Participants in our intervention were in a group setting that required interaction with an instructor and other class participants. Simple dual task (walking while having a conversation), complex dual tasks (walking while counting in a different language, walking, and reciting the alphabet skipping every other letter), motor-motor tasks (walking while tossing a ball) and response-inhibition exercises were incorporated into every class session. The cognitive process of set shifting has been independently associated with the quality of gait during complex dual task conditions.60 Participants were practicing these complex tasks every week, which may explain the improvements we saw in cognitive performance. The Trails B is more complex than A, requiring participants to locate numbers and letters and alternate between the 2.49 Participants varied greatly in their ability to perform this task, with 6 participants unable to complete the task at baseline, and a variation in performance of over 218 seconds, which is similar to other findings in the literature.5 Given this variability, we did not expect to see significant findings with the small number of participants; however, there was a trend toward improved performance in this task.
Our decision to perform a mixed model repeated measures ANOVA to determine if grouping according to baseline walking speed influenced outcomes provided interesting results. Those who walked slower at baseline also tended to have lower scores on the other physical and cognitive measures compared to the group with faster walking speeds. However, both groups demonstrated significant improvements in almost all the measures. There were no significant interactions between time and walking speed group for the physical measures, indicating that both groups improved, and baseline performance did not impact outcomes. A significant interaction did exist between walking speed group and time for the cognitive performance measures of Trails A and Trails B, indicating those with faster walking speeds demonstrated significantly greater improvements on these 2 cognitive measures.
Several baseline measures in the Slow Group (tandem, SLS, TCR, FSST, Walking Speed) were below standardized cut off times indicating the participants were at risk for falls and functional decline. After the 12-week intervention, the mean times were all above the cut offs for these measures than the cut-off measures, indicating the average score was no longer in the ‘at risk' range. The Fast Group demonstrated mean performance measures close to or greater than the scores typically used as cut offs associated with decline.
Both groups demonstrated improvements in the cognitive measures with the fast group improving significantly more that the slow group on Trails A and B. This finding suggests those with better physical performance at the onset may benefit in different ways from participation in the class. Walking speed has a strong association with executive function.61 It may be that those with baseline faster walking speeds may have more attentional resources to devote to the intervention and may experience different benefits. Further studies with larger samples should explore this question, as it may provide some clarifications in the variability of outcomes demonstrated in these types of interventions. Understanding why some individuals may benefit more than others or in different ways from an intervention has ramifications for clinicians. Understanding these differences could indicate a potential different focus for interventions and long-term falls, prevention given the physical skills of the individual in the class.
There were no clear differences at baseline between those who were posttested and those who were not. In general, the group that was not posttested had significantly worse performance of the timed chair rise, the 2 dynamic assessments of balance, and trends toward worse performance on all other measures except for walking speed and the single leg stance. A closer look at this group revealed that it was composed of 2 subgroups. One group could be defined as low performers in all areas. This group was composed of 10 individuals who could not perform the cognitive assessments or took all of the allotted time to complete and had physical performance scores that placed them in the very high-risk category of falling. Group 2 had a mix of individuals who were high performers on some assessments, and low performers on others. The characteristics of group 2 closely matched those that completed the post-test assessments. Individuals from group 2 did not finish the class due to scheduling conflicts, unrelated injuries, or lack of interest. Individuals from group 1 were those that stopped coming to class either because they were no longer interested, had health issues, or would not give a reason.
The main limitation to this study is the lack of a control group. We partnered with the local senior center to conduct this pilot study. A key aspect of this partnership was allowing all individuals who met class criteria to take the class. As this was a pilot study to gather preliminary data, we felt that the single group design was a viable option; however, it does not allow us to compare our results to a control group, which would provide insight to other factors affecting our results such as task learning, the effect of social interaction, and changes in self-efficacy. A second limitation was the attrition rate of the class. A total of 24 individuals (33%) did not complete the class for various reasons. These adherence rates may be the norm for community-based programs for seniors. Shumway-Cook et al62 also reported similar adherence rates for participants in the Enhanced Fitness program. Approximately, 35% of participants in that community-based exercise intervention attended fewer than 33% of classes over a 1-year period. Reasons for not attending class were similar to our study: illness, scheduling conflict, vacations, and busy schedules. Attendance was taken at all classes in our program and attendance rates ranged from 40% to 100% for any given 12-week session.
The delivery of the intervention by 2 different therapists could contribute to different outcomes between classes. To address this lack of consistency and insure fidelity to the class content, a script was developed for each class and replicated for each session. The therapists discussed the class curriculum and clarified any inconsistencies or confusion in wording. The therapists observed a minimum of 5 class sessions and provided feedback and critique to each other. To further assess if differences existed in content delivered, a 2-way ANOVA found no significant differences in outcomes of physical and cognitive performance between the groups taught by therapist #1 (n = 26). and therapist #2 (n = 26), found no significant differences in outcome measures. Finally, the short duration of the intervention and lack of follow up did not allow us to accurately track falls rates. Given the apparent improvement in physical and cognitive measures, we plan to address these limitations in a larger randomized controlled trial with subgroups based on initial balance ability.
The results of this study suggest that participating in an exercise class to improve balance may have an impact on cognition, and those individuals with better balance skills may experience greater cognitive benefits. Future randomized controlled trials with larger sample sizes need to refine these findings. First, we need to determine if cognition is a component of the protective effect against falls typically seen in exercise interventions. Then, if cognition is a factor we need to create algorithms to identify an individual's baseline level. Once identified, the individual could be placed in a class with a standardized curriculum based on baseline physical abilities that would progress the individual appropriately through a program that focused primarily on strength and balance, and then continue on to a more challenging program that incorporated more cognitive tasks.
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